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Review Article
Root and Root Canal Morphology of MaxillaryFirst Premolars: A Literature Review and ClinicalConsiderations
Ibrahim Ali Ahmad, BDS, MSc, JBE,* and Mohammad Ahmad Alenezi, BDS, MFDRCSI, MScD†‡Abstract
Introduction: Sound knowledge of the external andinternal morphology of the different teeth groups isessential to ensure a successful outcome of root canaltreatment. The aims of this study were to review theavailable literature with respect to the root and rootcanal morphology of maxillary first premolars anddiscuss the clinical considerations of this morphologyon the various dental procedures. Methods: TheMEDLINE/PubMed and Scopus databases were searchedfor relevant literature. The identified publications wereclassified into anatomic studies and clinical case reports.The data extracted from anatomic studies were tabu-lated, and weighted averages for certain internal andexternal morphologic features were calculated. Theanatomic and developmental variations in the clinicalcase reports were summarized. Results: A total of 92studies (45 anatomic studies and 47 case reports)including a total of 11,299 teeth were identified.The majority of maxillary first premolars had 1 root(41.7%) or 2 roots (56.6%). Regardless of the numberof roots, the vast majority (86.6%) had 2 root canals,with type IV (2-2) being the most common canal config-uration (64.8%). The majority of the apical foramina(66.6%) did not coincide with the apical root tip. About38% of the teeth had lateral canals, 12.3% had apicaldeltas, and 16.0% had isthmi. The clinical case reportsshowed that the 3-rooted variant was the most commonanatomic variation, and developmental anomalies wererarely reported. Conclusions: The maxillary first premo-lars are predominantly 2-rooted teeth with 2 root canals.However, the clinician should be aware about thepossible anatomic variations of these teeth and theirrelationship with the adjacent anatomic structureswhile planning and performing endodontic, restorative,periodontal, and surgical procedures. (J Endod2016;42:861–872)From the *Dentistry Department, Al-Wakra Hospital, Hamad MDentistry Department, College of Dentistry, Riyadh Colleges of Den
Address requests for reprints to Dr Ibrahim Ali Ahmad, Dentistryaddress: [email protected]/$ - see front matter
Copyright ª 2016 American Association of Endodontists.http://dx.doi.org/10.1016/j.joen.2016.02.017
JOE — Volume 42, Number 6, June 2016
Key WordsAnatomic variations, furcation grooves, maxillary first premolars, root canalmorphology, 3-rooted premolars
The success of root canal treatment depends on complete chemomechanical prepa-ration and 3-dimensional (3D) obturation of the root canal system. The inability
to locate, prepare, or obturate 1 or more of the root canals is a common causeof post-treatment disease or failure of endodontic treatment (1, 2). Therefore,clinicians should be familiar with the common root and root canal morphology andits possible variations in the different teeth groups before commencing endodontictreatment (3).
As a group, the maxillary premolars are common candidates for root canaltreatment and account for 15.8%–21.5% of all treated teeth (4, 5). Over theyears, the internal and external morphology of these teeth was investigated byusing different techniques. The maxillary first premolars typically have 2 rootsand 2 root canals, whereas the maxillary second premolars have 1 root with 1or 2 root canals (5–20). In addition, both premolars may have 3 roots with 3root canals (21, 22). Figure 1 illustrates 3 maxillary first premolars with differentroot and root canal morphologies.
Variations in root and root canal morphology may be attributed to a number offactors including ethnic background, gender and age of the study population, andthe evaluation technique (23). The objectives of this article were to do the following:
1. Review the anatomic studies and clinical cases that reported on the internal andexternal anatomy of maxillary first premolars.
2. Determine the factors that may affect the morphology of these teeth.3. Discuss the clinical considerations of morphology of these teeth on the various
dental procedures.
Materials and MethodsLiterature Search Strategy
The MEDLINE/PubMed (http://www.ncbi.nlm.nih.gov/pubmed) and Scopus(http://www.scopus.com) databases (last accessed January 15, 2016) were searchedto identify publishedmanuscripts related to themorphology of maxillary first premolarsby using combinations of the following key words: maxillary first premolars, rootmorphology, root canal morphology, anatomic variations, and dental anomalies. Afterremoval of duplicate articles, the title and abstract of the remaining articles were
edical Corporation, Al-Wakra, Qatar; †Ministry of Health, Kuwait City, Kuwait; and ‡Restorativetistry and Pharmacy, Riyadh, Kingdom of Saudi Arabia.Department, Al-Wakra Hospital, Hamad Medical Corp, Postal Box 82228, Al-Wakra, Qatar. E-mail
Morphology of Maxillary First Premolars 861
Figure 1. Maxillary first premolars with different root and canal morphol-ogies. (A) Single-rooted premolar with type III (1-2-1) canal configuration.(B) Two-rooted premolar with 2 buccal canals (2-2) and a single palatalcanal. (C) Three-rooted and 3-canalled premolar.
Review Article
screened by the 2 authors for their relevance according to the belowinclusion criteria, and potential articles were retrieved in full text.Then the reference list of each of these articles was manually checkedfor additional studies.
Inclusion CriteriaAnatomic studies and clinical case reports that evaluated the root
and/or root canal morphology of maxillary first premolars and werepublished in peer-reviewed journals were included in the currentreview.
Data Extraction and AnalysisOverall, 45 anatomic studies (5–10, 12–20, 24–53) including
11,228 teeth and 47 clinical case reports (54–100) of anatomic anddevelopmental variations including 71 teeth met the inclusion criteriaand were subjected to further analysis (Table 1).
The data extracted from the anatomic studies were divided intoexternal and internal morphologic features. The external featuresincluded the following:
1. The number of roots (Table 2). Some studies reported maxillaryfirst premolars with a single root that bifurcated in the middle orapical thirds (9, 17, 18, 20, 49). These teeth were classified as2-rooted premolars.
TABLE 1. Literature Search Strategy
Search termsNo. of
publications
1 Maxillary first premolars AND rootmorphology
269
2 Maxillary first premolars AND root canalmorphology
102
3 Maxillary first premolars AND anatomicvariations
7
4 Maxillary first premolars AND dentalanomalies
114
5 Total number of publications (1 + 2 + 3 + 4) 4926 (5) after removal of duplicate publications 3567 Publications remaining after title/abstract
screening68
8 Articles retrieved through manual search 249 Total included publications (7 + 8) 92
862 Ahmad and Alenezi
2. The presence and type of roots fusion (RF) in multirooted teeth(Table 2). The incidence of RF in 2-rooted and 3-rooted premolarswas calculated by dividing the number of teeth with RF by thenumber of 2-rooted and 3-rooted teeth, respectively. The overallincidence of RF was calculated by dividing the number of fused2-rooted and 3-rooted teeth by the total number of multirooted teethin the sample (ie, total sample number minus the number of single-rooted teeth). RF in 3-rooted teeth was classified into partial (fusionof 2 roots) or complete (fusion of all 3 roots).
The internal features included the following:
1. Total number of root canals per tooth (Table 3).2. Root canal configuration per tooth according to the 8 types of
Vertucci’s classifications (1). Additional canal configurations werereported by some studies (13, 16, 17, 40, 43, 53) and werecategorized as ‘‘others’’ (Table 3).
3. Morphology of the apical region and included the following(Table 4):� Number and position of apical foramina� Presence of apical deltas� Presence and location of lateral canals and isthmi
The weighted average of the aforementionedmorphologic featureswas calculated by dividing the total number of teeth with that feature bythe total number of samples in all studies that evaluated it.
For each clinical case report, the following data were extracted(Table 5):
1. Patient’s personal information (age, gender, and ethnicity ifmentioned)
2. Location of involved first premolar (#14 for right and #24 for left)3. Management of the involved tooth (clinical examination, radio-
graphic examination, or clinical procedure)4. Important anatomic variations and/or developmental anomalies
ResultsRoot Morphology
The root morphology was evaluated by 26 studies (5, 7–10,13–15, 17, 18, 20, 24, 27, 31, 33, 37, 39, 40, 43, 44, 47–49,51–53) that included a total of 6878 teeth (Table 2). The majority ofmaxillary first premolars (56.6%) had 2 roots, 41.7% had 1 root,and 1.7% had 3 roots. The 3-rooted premolars had either 2 buccalroots and a single palatal root or 2 palatal roots and a single buccalroot. One anatomic study (43) reported eight 3-rooted premolars, ofwhich 6 had 2 palatal roots and 1 buccal root, and the other 2 teethhad 2 buccal roots and 1 palatal root. All 3-rooted teeth in the clinicalcase reports had 2 buccal roots and 1 palatal root (Table 5).
Eight studies (14, 37, 39, 43, 44, 47, 52, 53) with a total of 1779teeth evaluated the presence of RF (Table 2). About one fourth of multi-rooted teeth (24.9%) had RF, and 2-rooted premolars had a higherincidence of RF than their 3-rooted counterparts (24.3% and 0.6%,respectively). RF in 3-rooted premolars was reported by 2 studies(37, 39), and it included either the buccal roots only (8 of 11 teeth)or all roots (3 of 11 teeth).
Root Canal MorphologyThe internal morphology was investigated by 41 studies including
10,013 teeth by using different techniques including tooth sectioning(15, 24, 28, 30, 39, 47), tooth modeling (7, 25), tooth staining andclearing (8, 10, 12, 13, 16–19, 26, 34, 35, 39, 40, 42–44, 53),conventional radiography (5, 6, 9, 27, 28, 31, 32, 36–38, 46, 49),and cone-beam computed tomography (20, 48, 50, 51).
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TABLE 2. Number of Roots and Presence of Roots Fusion (RF) in Maxillary First Premolars
Reference Country (population) Sample no.
No. of roots (%) RF (%)
1 2 3 2-RPM 3-RPM Total
Barrett, 1925 (24) USA 32 24 (66.7) 8 (33.3) 0 (0.0)Mueller, 1933 (27) USA 130 41 (31.5) 89 (68.5) 0 (0.0)Carns and Skidmore, 1973 (7) USA 100 37 (37.0) 57 (57.0) 6 (6.0)Hession, 1977 (31) Australia 12 1 (8.3) 11 (91.7) 0 (0.0)Vertucci, 1984 (8) USA 400 158 (39.5) 226 (56.5) 16 (4.0)De Deus, 1986 (33) Brazil (Brazilian) 108 38 (35.5) 66 (61.0) 4 (3.5)Walker, 1987 (9) South China (Chinese) 100 60 (60.0) 40 (40.0) 0 (0.0)P�ecora et al, 1991 (10) Brazil (Brazilian) 240 134 (55.8) 100 (41.7) 6 (2.5)Zaatar et al, 1997 (5) Kuwait (Kuwaiti) 79 34 (43.0) 42 (53.2) 3 (3.8)Kartal et al, 1998 (13) Turkey (Turkish) 300 112 (37.3) 184 (61.3) 4 (1.3)Loh, 1998 (14) Singapore (Singaporean) 957 473 (49.4) 484 (50.6) 0 (0.0) 155 (32.0) 0 (0.0) 155 (32.0)Chaparro et al, 1999 (15) South Spain (Andalusian) 150 60 (40.0) 85 (56.7) 5 (3.3)Lipski et al, 2005 (37) Poland (Polish) 142 22 (15.5) 107 (75.3) 13 (9.2) 37 (34.6) 8 (61.5) 45 (37.5)Atieh, 2008 (39) Saudi Arabia (Saudi) 246 44 (17.9) 199 (80.9) 3 (1.2) 89 (44.7) 3 (100) 92 (45.5)Awawdeh et al, 2008 (17) Jordan (Jordanian) 600 185 (30.8) 410 (68.4) 5 (0.8)Cheng and Weng, 2008 (40) China (Chinese) 422 242 (57.4) 175 (41.5) 5 (1.2)Peiris, 2008 (18) Japan (Sri Lankan) 153 82 (53.7) 71 (46.3) 0 (0.0)
Japan (Japanese) 81 62 (76.6) 18 (22.2) 1 (1.2)Neelakantan et al, 2011 (43) India (Indian) 350 41 (11.7) 301 (86.0) 8 (2.3) 7 (2.3) 0 (0.0) 7 (2.3)Rwenyonyi et al, 2011 (44) Uganda (Ugandan) 202 54 (26.7) 148 (73.3) 0 (0.0) 25 (16.9) 0 (0.0) 25 (16.9)€Ozcan et al, 2012 (47) Turkey (Turkish) 653 295 (45.2) 351 (55.7) 7 (1.1) 37 (10.5) 0 (0.0) 37 (10.3)Tian et al, 2012 (20) China (Chinese) 300 198 (66.0) 100 (33.3) 2 (0.7)Elkady and Allouba, 2013 (48) Saudi Arabia (Saudi) 120 34 (28.3) 86 (71.7) 0 (0.0)Kocani et al, 2014 (49) Kosovo (Kosovar) 221 48 (21.7) 155 (70.1) 18 (8.1)Abella et al, 2015 (51) Spain (Spanish) 430 198 (46.0) 221 (51.4) 11 (2.6)Dashrath et al, 2015 (52) Nepal (Nepalese) 100 58 (58.0) 41 (41.0) 1 (1.0) 21 (51.2) 0 (0.0) 21 (50.0)Gupta et al, 2015 (53) India (Indian) 250 134 (53.6) 115 (46.0) 1 (0.4) 61 (53.0) 0 (0.0) 61 (52.6)No. of roots (26 studies) 6878 2869 (41.7) 3890 (56.6) 119 (1.7)Incidence of RF (8 studies) 1779* 432 (24.3) 11 (0.6) 443 (24.9)
2-RPM, 2-rooted premolars; 3-RPM, 3-rooted premolars.
*Included only the number of 2-rooted and 3-rooted teeth. ReviewArticle
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TABLE 3. Number and Configurations of Root Canals (per tooth) in Maxillary First Premolars
Study Country (population) Type of study Sample no.
Barrett, 1925 (24) USA In vitro (LS) 32Hess, 1925 (25) Switzerland In vitro (modeling) 260Okumura, 1927 (26) Japan In vitro (clearing) 85Mueller, 1933 (27) USA In vitro (radiography) 130Green, 1955 (28) USA In vitro (radiography and LS) 10Pineda and Kuttler, 1972 (6) Mexico In vitro (radiography) 259Carns and Skidmore, 1973 (7) USA In vitro (modeling) 100Green, 1973 (30) USA In vitro (LS) 50Hession, 1977 (31) Australia In vitro (radiography) 12Vertucci, 1984 (8) USA In vitro (clearing) 400Bellizzi and Hartwell, 1985 (32) USA In vivo (radiography) 514Walker, 1987 (9) South China (Chinese) In vitro (radiography) 100P�ecora et al, 1991 (10) Brazil (Brazilian) In vitro (clearing) 240Caliskan et al, 1995 (12) Turkey (Turkish) In vitro (clearing) 100Wu et al, 1995 (34) China (Chinese) In vitro (clearing) 100Zaatar et al, 1997 (5) Kuwait (Kuwaiti) In vivo (radiography) 79Kartal et al, 1998 (13) Turkey (Turkish) In vitro (clearing) 300Chaparro et al, 1999 (15) South Spain (Andalusian) In vitro (CS) 150Deng et al, 2004 (35) China (Chinese) In vitro (clearing) 326Oginni, 2004 (36) Nigeria (Nigerian) In vivo (radiography) 122Sert and Bayirli, 2004 (16) Turkey (Turkish) In vitro (clearing) 100 (male)
100 (female)Lipski et al, 2005 (37) Poland (Polish) In vitro (radiography) 142Mattuella et al, 2005 (38) Brazil (Brazilian) In vitro (radiography) 39 (BRs)Atieh, 2008 (39) Saudi Arabia (Saudi) In vitro (clearing and CS) 246Awawdeh et al, 2008 (17) Jordan (Jordanian) In vitro (clearing) 600Cheng and Weng, 2008 (40) China (Chinese) In vitro (clearing) 422Peiris, 2008 (18) Japan (Sri Lankans) In vitro (clearing) 153
Japan (Japanese) In vitro (clearing) 81R�o _zy1o et al, 2008 (41) Poland (Polish) In vitro (exploration with hand files) 83Weng et al, 2009 (19) China (Chinese) In vitro (clearing) 95Ng’ang’a et al, 2010 (42) Kenya (Kenyan) In vitro (clearing) 77 (male)
78 (female)Neelakantan et al, 2011 (43) India (Indian) In vitro (clearing)
Single-rooted PM 412-rooted PM 301 BR
301 PR3-rooted PM 2 MBR
2 DBR2 PR
3-rooted PM 6 BR6 MPR6 DPR
Rwenyonyi et al, 2011 (44) Uganda (Ugandan) In vitro (clearing) 202Sharma and Mathur, 2011 (45) India (Indian) In vitro (CT) 60Al-Nazhan et al, 2012 (46) Saudi Arabia (Saudi) In vivo (radiography) 163 (male)
300 (female)€Ozcan et al, 2012 (47) Turkey (Turkish) In vitro (radiography and CS) 653Tian et al, 2012 (20) China (Chinese) In vivo (CBCT) 300Elkady and Allouba, 2013 (48) Saudi Arabia (Saudi) In vivo (CBCT) 120Kocani et al, 2014 (49) Kosovo (Kosovar) In vitro (DOM and CDR) 221Ok et al, 2014 (50) Turkey (Turkish) In vivo (CBCT) 1379Abella et al, 2015 (51) Spain (Spanish) In vivo (CBCT) 430Gupta et al, 2015 (53) India (Indian) In vitro (clearing) 250No. of root canals (39 studies)# 9624Root canal configurations (28 studies)# 7695
BR, buccal root; CBCT, cone-beam computed tomography; CDR, computed digital radiography; CS, cross-sectioning; CT, computed tomography; DBR, distobuccal root; DOM, dental operating microscope;
DPR, distopalatal root; LS, longitudinal sectioning; MBR, mesiobuccal root; MPR, mesiopalatal root; PM, premolar; PR, palatal root; RCT, root canal treatment.
* Type 2-3 (0.3%).
† Type 1-2-3-2 (3%).
‡ Types 3-2 (0.5%) and 2-3-2-3 (0.2%).
§ Type 1-3 (0.5%).
k Type 2-3 (0.7%) and 2-1-2-1 (1.0%).¶ Type 2-1-2-1 (1.2%) and 1-2-1-3 (0.8%).
# Two studies were excluded from calculations of weighted averages. The first study (38) evaluated the root canal system in the buccal roots only, and the second one (43) studied the root canal morphology
of each root separately.
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864 Ahmad and Alenezi JOE — Volume 42, Number 6, June 2016
No. of canals (%) Canal configurations (%)
1 2 3 I II III IV V VI VII VIII Other
9 (28.1) 22 (68.8) 1 (3.1)51 (19.5) 206 (79.3) 3 (1.2)7 (8.2) 78 (91.8) 0 (0.0)2 (1.5) 128 (98.5) 0 (0.0)1 (10.0) 9 (90.0) 0 (0.0)
68 (26.2) 190 (73.3) 1 (0.5) 68 (26.2) 62 (23.9) 0 (0.0) 108 (41.7) 20 (7.7) 0 (0.0) 0 (0.0) 1 (0.5) 0 (0.0)9 (9.0) 85 (85.0) 6 (6.0) 9 (9.0) 13 (13.0) 0 (0.0) 72 (72.0) 0 (0.0) 0 (0.0) 0 (0.0) 6 (6.0) 0 (0.0)4 (8.0) 46 (92.0) 0 (0.0) 4 (8.0) 13 (26.0) 0 (0.0) 33 (66.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (8.3) 10 (83.3) 1 (8.3)
32 (8.0) 348 (87.0) 20 (5.0) 32 (8.0) 72 (18.0) 0 (0.0) 248 (62.0) 28 (7.0) 0 (0.0) 0 (0.0) 20 (5.0) 0 (0.0)32 (6.2) 465 (90.5) 17 (3.3)13 (13.0) 87 (87.0) 0 (0.0)41 (17.1) 193 (80.4) 6 (2.5)4 (3.9) 96 (96.1) 0 (0.0) 4 (3.9) 6 (5.9) 0 (0.0) 78 (78.4) 6 (5.9) 6 (5.9) 0 (0.0) 0 (0.0) 0 (0.0)
11 (11.0) 89 (89.0) 0 (0.0) 11 (11.0) 26 (26.0) 5 (5.0) 49 (49.0) 4 (4.0) 5 (5.0) 0 (0.0) 0 (0.0) 0 (0.0)9 (11.4) 67 (84.8) 3 (3.8) 9 (11.4) 8 (10.1) 0 (0.0) 59 (74.7) 0 (0.0) 0 (0.0) 0 (0.0) 3 (3.8) 0 (0.0)
26 (8.7) 269 (89.6) 5 (1.7) 26 (8.7) 3 (1.0) 0 (0.0) 214 (71.3) 44 (14.7) 7 (2.3) 1 (0.3) 4 (1.3) 1 (0.3)*2 (1.3) 143 (95.3) 5 (3.3) 2 (1.3) 56 (37.3) 0 (0.0) 87 (58.0) 0 (0.0) 0 (0.0) 0 (0.0) 5 (3.3) 0 (0.0)
159 (48.8) 165 (50.6) 2 (0.6) 159 (48.8) 32 (9.8) 8 (2.4) 118 (36.2) 0 (0.0) 7 (2.1) 0 (0.0) 2 (0.6) 0 (0.0)18 (14.8) 104 (85.2) 0 (0.0) 18 (14.8) 36 (29.5) 0 (0.0) 68 (55.7) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)9 (9.0) 86 (86.0) 5 (5.0) 9 (9.0) 13 (13.0) 6 (6.0) 60 (60) 5 (5.0) 0 (0.0) 2 (2.0) 2 (2.0) 3 (3.0)†
12 (12.0) 84 (84.0) 4 (4.0) 12 (12.0) 12 (12.0) 5 (5.0) 63 (63.0) 2 (2.0) 2 (2.0) 0 (0.0) 4 (4.0) 0 (0.0)3 (2.1) 126 (88.7) 13 (9.2) 3 (2.1) 9 (6.3) 0 (0.0) 117 (82.4) 0 (0.0) 0 (0.0) 0 (0.0) 13 (9.2) 0 (0.0)7 (17.1) 32 (82.9) 0 (0.0)
22 (8.9) 221 (89.8) 3 (1.2) 22 (8.9) 66 (26.8) 0 (0.0) 155 (63.0) 0 (0.0) 0 (0.0) 0 (0.0) 3 (1.2) 0 (0.0)20 (3.3) 567 (94.5) 13 (2.2) 20 (3.3) 61 (10.2) 2 (0.3) 478 (79.7) 12 (2.0) 14 (2.3) 0 (0.0) 9 (1.5) 4 (0.7)‡
43 (10.1) 371 (87.8) 8 (1.9) 43 (10.1) 45 (10.6) 25 (6.0) 239 (56.6) 51 (12.1) 8 (1.9) 3 (0.7) 6 (1.5) 2 (0.5)§
2 (1.3) 145 (94.8) 0 (0.0) 2 (1.3) 25 (16.3) 3 (2.0) 98 (64.0) 9 (5.9) 9 (5.9) 1 (0.7) 0 (0.0) 6 (3.9)4 (4.9) 72 (88.9) 0 (0.0) 4 (4.9) 24 (29.6) 2 (2.5) 37 (45.7) 2 (2.5) 7 (8.6) 0 (0.0) 0 (0.0) 5 (6.2)
25 (30.1) 53 (63.9) 5 (6.0)6 (6.3) 89 (93.7) 0 (0.0) 6 (6.3) 21 (22.1) 3 (3.2) 61 (64.2) 3 (3.2) 1 (1.0) 0 (0.0) 0 (0.0) 0 (0.0)2 (2.6) 66 (85.7) 9 (11.7) 2 (2.6) 2 (2.6) 0 (0.0) 53 (68.8) 11 (14.3) 0 (0.0) 0 (0.0) 9 (11.7) 0 (0.0)1 (1.3) 76 (97.4) 1 (1.3) 1 (1.3) 2 (2.6) 3 (3.8) 58 (74.4) 9 (11.5) 1 (1.3) 3 (3.8) 1 (1.3) 0 (0.0)
9 (21.9) 32 (78.1) 0 (0.0) 9 (21.9) 14 (34.1) 3 (7.5) 11 (26.8) 4 (9.7) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)99 (32.9) 200 (66.4) 2 (0.7) 99 (32.9) 42 (13.9) 58 (19.3) 36 (12.0) 61 (20.3) 0 (0.0) 0 (0.0) 0 (0.0) 5 (1.7)k
252 (83.7) 49 (16.3) 0 (0.0) 252 (83.7) 32 (10.6) 0 (0.0) 2 (0.7) 15 (5.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (50.0) 1 (50.0) 0 (0.0) 1 (50.0) 0 (0.0) 1 (50.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (50.0) 1 (50.0) 0 (0.0) 1 (50.0) 0 (0.0) 0 (0.0) 0 (0.0) 1 (50.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (50.0) 1 (50.0) 0 (0.0) 1 (50.0) 0 (0.0) 1 (50.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (16.6) 5 (83.4) 0 (0.0) 1 (16.6) 1 (16.6) 1 (16.6) 1 (16.6) 2 (33.6) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (16.6) 5 (83.4) 0 (0.0) 1 (16.6) 0 (0.0) 0 (0.0) 0 (0.0) 5 (83.4) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)1 (16.1) 5 (83.4) 0 (0.0) 1 (16.6) 0 (0.0) 1 (16.6) 0 (0.0) 4 (66.8) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0)7 (3.5) 190 (94.0) 5 (2.5) 7 (3.5) 16 (7.9) 1 (0.5) 169 (83.6) 1 (0.5) 1 (0.5) 2 (1.0) 5 (2.5) 0 (0.0)3 (5.0) 57 (95.0) 0 (0.0) 3 (5.0) 15 (25.0) 5 (8.3) 27 (45.0) 7 (11.7) 2 (3.3) 1 (1.7) 0 (0.0) 0 (0.0)5 (3.1) 150 (92) 8 (4.9)
12 (4.0) 285 (95.0) 3 (1.0)51 (7.8) 592 (90.7) 10 (1.5) 51 (7.8) 145 (22.2) 0 (0.0) 447 (68.5) 0 (0.0) 0 (0.0) 0 (0.0) 10 (1.5) 0 (0.0)43 (14.3) 255 (85.0) 2 (0.7) 43 (14.3) 70 (23.3) 13 (4.3) 153 (51.0) 10 (3.3) 7 (2.3) 2 (0.7) 2 (0.7) 0 (0.0)6 (5.0) 114 (95.0) 0 (0.0) 6 (5.0) 6 (5.0) 12 (10.0) 84 (70.0) 8 (6.7) 0 (0.0) 4 (3.3) 0 (0.0) 0 (0.0)4 (1.8) 199 (90.0) 18 (8.1) 4 (1.8) 12 (5.4) 1 (0.4) 186 (84.2) 0 (0.0) 0 (0.0) 0 (0.0) 18 (8.1) 0 (0.0)
132 (9.6) 1233 (89.4) 14 (1.0) 132 (9.6) 89 (6.5) 19 (1.4) 1061 (76.9) 63 (4.6) 1 (0.1) 0 (0.0) 14 (1.0) 0 (0.0)108 (25.1) 311 (72.3) 11 (2.6) 108 (25.1) 44 (10.2) 19 (4.4) 227 (52.8) 8 (1.9) 7 (1.6) 6 (1.4) 11 (2.6) 0 (0.0)58 (23.2) 189 (75.6) 3 (1.2) 58 (23.2) 37 (14.8) 34 (13.6) 83 (33.2) 17 (6.8) 5 (2.0) 10 (4.0) 1 (0.4) 5 (2.0)¶
1077 (11.2) 8331 (86.6) 216 (2.2)878 (11.4) 1041 (13.5) 166 (2.2) 4990 (64.8) 320 (4.2) 90 (1.2) 35 (0.5) 149 (1.9) 26 (0.3)
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JOE — Volume 42, Number 6, June 2016 Morphology of Maxillary First Premolars 865
TABLE 4. Morphology of Apical Region
Study Study methodologySample(tooth)
Apical foramina (%)
Apicaldelta (%)
Lateralcanals (%) Isthmi (%)
Number Location
1 2 $3 Centric Eccentric
Green, 1960 (29) In vitro (microscopy) 50 (R) 24 (47.0) 26 (53.0)Pineda and Kuttler, 1972 (6) In vitro (radiography) 259 130 (50.1) 128 (49.4) 1 (0.5)
390 (RC) 43 (11.0) 347 (89.0) 7 (1.8) 161 (41.3)Carns and Skidmore, 1973 (7) In vitro (modeling) 100 22 (22.0) 72 (72.0) 6 (6.0)Green, 1973 (30) In vitro (LS) 50 17 (34.0) 33 (66.0) 0 (0.0)Hession, 1977 (31) In vitro (radiography) 12 1 (8.3) 4 (33.3)Vertucci, 1984 (8) In vitro (clearing) 400 104 (26.0) 276 (69.0) 20 (5.0) 48 (12.0) 352 (88.0) 13 (3.2) 198 (49.5) 137 (34.2)Walker, 1987 (9) In vitro (radiography) 100 36 (36.0) 64 (64.0) 0 (0.0)Caliskan et al, 1995 (12) In vitro (clearing) 100 10 (9.8) 90 (90.2) 0 (0.0) 33 (33.3) 67 (66.7) 22 (21.6) 33 (33.3) 18 (17.6)Wu et al, 1995 (34) In vitro (clearing) 100 42 (42.0) 58 (58.0) 0 (0.0) 9 (9.0)Kartal et al, 1998 (13) In vitro (clearing) 300 29 (9.7) 266 (88.6) 5 (1.7) 46 (15.3) 254 (84.7) 69 (23.0) 234 (78.0) 63 (21.0)Chaparro et al, 1999 (15) In vitro (CS) 150 58 (38.7) 87 (58.0) 5 (3.3)Deng et al, 2004 (35) In vitro (clearing) 326 199 (61.0) 125 (38.3) 2 (0.6) 46 (14.1) 138 (42.5)Sert and Bayirli, 2004 (16) In vitro (clearing) 200 57 (28.5) 137 (68.5) 6 (3) 47 (23.5) 153 (76.5) 61 (30.5) 66 (33.0) 24 (12.0)Awawdeh et al, 2008 (17) In vitro (clearing) 600 83 (13.8) 507 (84.5) 10 (1.7) 360 (60.0) 240 (40.0) 26 (4.3) 116 (19.3) 42 (7.0)Peiris, 2008 (18) In vitro (clearing) 153 (Sri Lanka) 30 (19.6) 122 (79.7) 1 (0.7)
81 (Japan) 30 (37.0) 48 (59.3) 3 (3.7)Weng et al, 2009 (19) In vitro (clearing) 95 30 (31.6) 65 (68.4) 0 (0.0)
178 (RC) 52 (29.2) 92 (51.7)Rwenyonyi et al, 2011 (44) In vitro (clearing) 202 24 (11.9) 173 (85.6) 5 (2.5) 57 (28.2) 5 (2.5)Gupta et al, 2015 (53) In vitro (clearing) 250 121 (48.4) 127 (50.8) 2 (0.8) 87 (34.8) 40 (16.0)No. of apical foramina (16 studies) 3466 1022 (29.5) 2378 (68.6) 66 (1.9)Position of apical foramina (7 studies)* 1600 534 (33.4) 1066 (66.6)Incidence of apical delta (9 studies)† 1938 238 (12.3)Incidence of lateral canals (12 studies)† 2490 942 (37.8)Incidence of isthmi (7 studies) 2052 329 (16.0)
CS, cross sectioning; LS, longitudinal sectioning; R, roots; RC, root canal.
*Two studies were excluded because they reported the position of apical foramina by the number of roots (29) or root canals (6).†Two studies (6, 19) were excluded because they reported the incidence of apical delta and lateral canals by the number of root canals.
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TABLE 5. Summary of Clinical Case Reports of Maxillary First Premolars Showing Anatomic Variations and Developmental Anomalies
Study Country Tooth Gender Age (y) Procedure Key anatomic features
Barry et al, 1975 (54) USA 14 Male 28 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Gazit and Lieberman, 1983 (55) USA 14 Male 13 Radiographic examination and inspection
of extracted tooth2-rooted tooth with missing PR
Maibaum, 1989 (56) USA 24 Female 71 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Zaatar et al, 1990 (57) Kuwait 24 Male 34 Clinical RCT 3 canals (MB, DB, and P)
24 Male 29 Clinical RCT 2 BRs and 1 PR (each with 1 canal)14 Male 24 Clinical RCT 3 canals (MB, DB, and P)
Augsburger and Wong, 1996 (58) Guam 14, 24 Female 12 Apexification Dens evaginatusNahmias and Rampado, 2002 (59) Canada 24 Female 17 Clinical RCT Gemination with trifid crown and type
4-3-2 canal configurationStecker and DiAngelis, 2002 (60) USA 14, 24 Female 9 Clinical examination Dens evaginatusSoares and Leonardo, 2003 (61) Brazil 24 NM 23 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Evans, 2004 (62) Australia 24 Female 65 Clinical RCT and apicectomy 2 BRs and 1 PR (each with 1 canal)�Segovi�c et al, 2004 (63) Croatia 14 NM NM Clinical RCT 2 BRs and 1 PR (each with 1 canal)
14 NM NM Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)24 NM NM Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)24 NM NM Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)14 NM NM Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)
Oruco�glu and Cobankara, 2005 (64) Turkey 24 Male 51 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Rekha et al, 2005 (65) India 24 Female 21 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Woodmansey, 2006 (66) USA 24 Male 20 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Jafarzadeh, 2007 (67) Iran 14, 24 Male 17 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Parolia et al, 2007 (68) India 14 Male 37 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Javidi et al, 2008 (69) Iran 24 Male 23 Clinical RCT 3 canals (MB, DB. and P)
24 Male 35 Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)14 Female 28 Clinical Re-RCT 2 BRs and 1 PR (each with 1 canal)
Arisu and Alacam, 2009 (70) Turkey 14 Male 24 Clinical RCT 2 BRs and 1 PR (each with 1 canal)24 Male 32 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
Cardinali et al, 2009 (71) Italy 24 NM 53 Clinical RCT 3 canals (MB, DB, and P)Dadresanfar et al, 2009 (72) Iran 24 Male 24 Clinical RCT 2 BRs (type 1-2 canal) and 1 PR (1 canal)Al-Abdulwahhab et al, 2010 (73) Saudi Arabia 24 Female 32 Clinical Re-RCT 3 canals (MB, DB, and P)Farooq et al, 2010 (74) India 24 Male 26 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
14 Male 16 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Abraham and Kumar, 2011 (75) India 24 Female 32 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Idris et al, 2011 (76) India 14 Male 27 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Karumaran et al, 2011 (77) India 24 Male 40 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
24 Male 21 Clinical RCT 2 BRs (type 1-2 canal) and 1 PR (1 canal)14 Male 24 Clinical RCT 3 canals (MB, DB, and P)
Nica et al, 2011 (78) Romania 14 Female 51 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Aracena et al, 2012 (79) Chile 24 NM 22 Inspection of extracted tooth 2 BRs and 1 PR (each with 1 canal)Chauhan and Chandra, 2012 (80) India 24 Male 43 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Colak et al, 2012 (81) Turkey 14 Female 26 Clinical examination Dens evaginatusGandhi et al, 2012 (82) India 14, 24 Female 25 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Garapati et al, 2012 (83) India 24 Male 51 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Gupta et al, 2012 (84) India 24 Male 45 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
14 Male 45 Radiographic examination 3 separate rootsKamath et al, 2012 (85) India 24 Female 63 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
14 Male 32 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Nimigean et al, 2013 (86) Romania 14 Female 22 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Ocak and Ahmeto�glu, 2013 (87) Turkey 14 Male 28 Clinical RCT 2 BRs and 1 PR (each with 1 canal)Oporto et al, 2013 (88) Chile 14 Female 32 Clinical RCT 2 BRs and 1 PR (each with 1 canal)
(Continued )
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JOE—
Volume42,
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ber6,June
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ofMaxillary
FirstPrem
olars867
TABLE5.
(Continued)
Study
Country
Tooth
Gen
der
Age(y)
Procedure
Key
anatomicfeatures
Relvasetal,2013(89)
Brazil
14
Female
16
ClinicalRCT
3canals(M
B,DB,andP)
Sulaim
anetal,2013(90)
Iran
14
Female
50
ClinicalRCT
3canals(M
B,DB,andP)
VictorinoandMen-M
artins,2013(91)
Brazil
14
Male
32
ClinicalRCT
2BRsand1PR(each
with1canal)
Chandra
andMathew,2014(92)
India
24
Female
38
ClinicalRCT
2BRsand1PR(each
with1canal)
14
Female
38
Radiographic
exa
mination
3separate
roots
Gopaletal,2014(93)
India
14,24
Female
34
ClinicalRCT
2BRsand1PR(each
with1canal)
Jaye
shetal,2014(94)
India
14
Male
13
Inspectionofextractedtooth
2BRsand1PR(each
with1canal)
Kirilova
etal,2014(95)
Bulgaria
14
NM
NM
ClinicalRCT
2BRsand1PR(each
with1canal)
24
NM
NM
ClinicalRCT
2BRsand1PR(each
with1canal)
14
NM
NM
ClinicalRCT
2BRsand1PR(each
with1canal)
24
NM
21
ClinicalRCT
3canals(M
B,DB,andP)
24
NM
NM
ClinicalRCT
3canals(M
B,DB,andP)
Mantrietal,2014(96)
India
24
Male
24
ClinicalRe-RCT
2BRsand1PR(each
with1canal)
Theruviletal,2014(97)
India
24
Female
45
ClinicalRCT
3canals(M
B,DB,andP)
Davo
udiandAkhava
n,2015(98)
Iran
24
Male
40
ClinicalRCT
3canals(M
B,DB,andP)
Mathew
etal,2015(99)
India
14
Male
25
ClinicalRCT
2BRsand1PR(each
with1canal)
Prave
enetal,2015(100)
India
14
Male
50
ClinicalRCT
2BRsand1PR(each
with1canal)
#14,maxillaryrightfirstprem
olar;#24,maxillaryleftfirstprem
olar;BR,buccalroot;DB,distobuccal;MB,mesiobuccal;NM,notmentioned;P,palatal;PR,palatalroot;Re-RCT,nonsurgicalrootcanalretreatment;RCT,rootcanaltreatment.
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868 Ahmad and Alenezi
When the total number of canals per tooth was considered, 8331(86.6%) had 2 canals, 1077 (11.2%) had 1 canal, and only 216(2.2%) had 3 canals. Type IV was the most prevalent (64.8%) rootcanal configuration, followed by types II (13.5%) and I (11.4%). Inaddition, about 0.3% of the investigated teeth demonstrated additionalconfigurations such as 1-3, 2-3, 1-2-1-3, 1-2-3-2, 3-2, 2-3-2-3, and2-1-2-1 (Table 3). The 3-rooted variant always had only 1 canal ineach root (5, 7, 8, 10, 13, 15, 17, 20, 37, 39, 40, 47, 49, 51). Thisfinding was also evident in the clinical cases that reported this variant(Table 5).
Apical Region MorphologyThe morphology of apical region was investigated by 18 studies
including 3528 teeth. The majority of the teeth had 1 foramen(29.5%) or 2 foramina (68.6%), and the majority of these foramina(66.6%) did not coincide with the apical root tip. About 38% of the teethhad lateral canals that were found most frequently in the apical third ofthe roots. Apical deltas and isthmi were found in 12.3% and 16.0% ofthe teeth, respectively.
Anatomic Variations and Developmental AnomaliesThe most common anatomic variation reported in the clinical case
reports was the presence of 3 roots with 3 root canals (54, 56, 57,61–70, 72, 74–80, 82–88, 91–96, 99, 100). Some cases (57, 69,71, 73, 77, 89, 90, 95, 97, 98) reported the presence of 3 rootcanals without specifying the number of roots (Table 5). Developmentalanomalies in maxillary first premolars are very rare. Hamasha andAlomari (101) studied the presence of dens invaginatus in the Jorda-nian population and found that only 0.4% of the maxillary first premo-lars had dens invaginatus. Darwazeh et al (102) and Pillai et al (103)reported that the incidence of taurodontism in maxillary first premolarsis rare, ranging from 0.1% to 0.4%. Few developmental anomalies werealso documented in clinical case reports including the presenceof dens evaginatus (58, 60, 81), gemination (59), and congenitallymissing palatal root (55).
DiscussionThe objectives of this article were to review the available literature
on the root and root canal morphology of the maxillary first premolarsand to discuss the clinical implications of their internal and externalmorphology on the various dental procedures. The data analyzed inthe current review are secondary data that have been extracted frompreviously published studies that had variations in their methodology,sample number, and study population. Therefore, although theweighted averages in the current review represent the most commonanatomic features of maxillary first premolars, clinicians should alwaysexpect morphologic variations in these teeth and use their knowledgeand available tools to detect andmanage them. There are several clinicalguidelines and tools that may be used to locate and negotiate root canalsincluding careful radiographic interpretation, proper access cavitydesign, careful inspection of the pulp floor to locate canal orifices,enhance the vision in the operating field by using magnifying toolssuch as eye loupes and dental operating microscope, use of advancedimaging techniques such as cone-beam computed tomography, andallocating sufficient time for treatment (1, 2).
The current review showed that the maxillary first premolars arepredominantly 2-rooted teeth with 2 root canals and that the most com-mon anatomic variation in these teeth is the presence of 3 roots with3 root canals. Three-rooted premolars are also known as radiculouspremolars, miniature 3-canalled molars, small molars, or mini-molars (21, 22, 56) and have an overall incidence of 1.7% (range,
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Figure 2. Furcation groove. (A) Proximal view showing presence of thegroove (arrow) on palatal aspect of buccal root. (B) Cross section of sampletooth showing the groove on the buccal root (arrow).
Review Article
0.4%–9.2%) (5, 7, 8, 10, 13, 15, 17, 18, 20, 33, 37, 39, 40, 43, 47,51–53). These teeth usually have 2 buccal roots and 1 palatal rootor less commonly 1 buccal root and 2 palatal roots, and each rootusually has only 1 root canal (Tables 3 and 5). The detection andmanagement of these premolars begin with careful clinical andradiographic examination. A wide mesiodistal dimension of thecrown compared with its buccolingual dimension may indicate thepresence of extra roots or root canals. Whenever the mesiodistalwidth of the mid root region on the preoperative radiograph is equalto or greater than the mesiodistal width of the crown, the tooth islikely to have an extra root (21, 22). Angulated periapical radiographsand 3D imaging techniques can be also used to confirm the presenceof extra roots or root canals. When 3 canals are present, the outlineform of the access cavity is changed from the traditional oval shape tobecome triangular with the base on the buccal side while apex onpalatal side (or vice versa in teeth with 2 palatal roots and 1 buccalroot), resulting in a cavity with a T-shaped outline (22).Clinicians should pay attention to morphology of the apicalregion during surgical and nonsurgical root canal treatment. The cur-rent review showed the majority of apical foramina did not coincidewith the apical root tips. It has been reported that deviation of theforamen is not easily detected radiographically, particularly whenthe opening occurs on the buccal or lingual root surfaces (6). There-fore, it is recommended to confirm the radiographic working lengthwith electronic apex locators, which have been reported to be highlyaccurate in determining the location of apical foramen (104). Thelateral canals may be found at any level of the root but are more com-mon in the apical third. They are rarely d�ebrided during cleaning andshaping but may occasionally be filled with obturating materials duringcanal obturation. These canals may act as avenues for the extension ofinflammatory breakdown products from the dental pulp to the peri-odontal tissues or vice versa, affecting the outcome of endodontictreatment and the maintenance of periodontal health (105). The pres-ence of apical deltas and isthmi may also be of clinical significancebecause it may be difficult to d�ebride and fill these areas adequately,and this may predispose to endodontic failure. Adequate irrigationduring nonsurgical treatment and activation of the irrigant with ultra-sonics may help to reach these uninstrumented parts of the root canalsystem (106). Surgical root canal treatment involves resecting the api-cal third of the root, thus removing the majority of canal irregularitiesincluding lateral canals and apical deltas. All apical foramina andisthmi on the resected root surface should be prepared and filled toseal the apical end of the root (107).
Certain external anatomic features including furcation groovesand root curvature should also be taken into consideration duringdental procedures involving maxillary premolars. The furcation groove(also known as furcal concavity, buccal furcation groove, or develop-mental depression) is a depression that is found on the palatal aspectof the buccal root in 2-rooted premolars, and its incidence in maxillaryfirst premolars ranges from 62% (108) to 100% (17, 109–113)(Fig. 2). The existence of furcation grooves has clinical implicationson endodontic, restorative, and periodontal procedures. Most of thesegrooves are located in the coronal two thirds of the buccal root, andtheir length varies from 1.1 to 9.0 mm (112, 113). In the area of thedeepest invagination, the average dentin thickness of the palatal wallranges from 0.78 to 1.18 mm (109–114). It is generallyrecommended that the post should be surrounded by a minimumof 1 mm of sound dentin (110, 115). Endodontic treatment andpost space preparation may jeopardize root integrity in this ‘‘dangerzone’’ and lead to root perforation. Therefore, clinicians shouldavoid overpreparation of this area during root canal treatment andplace the post, if needed, in the palatal root canal (110, 115).
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Furthermore, these grooves are potential sites for plaque andcalculus and may predispose these teeth to periodontal disease (108).
The presence of root curvature is another important parameterthat should be considered during endodontic and restorative treat-ments. Sch€afer et al (116) investigated the frequency and degree ofcanal curvatures in extracted permanent teeth by using a standardizedradiographic technique from the buccal and proximal views. Themajority of buccal (85%) and palatal (87%) root canals in maxillaryfirst premolars had at least 1 curve along their length. Depending onthe radiographic view and canal type, the median angle of curvatureranged from 10� to 13�, the median radius of curvature ranged from5.9 to 8.8 mm, and the median length of curvature ranged from 2.5to 4.2 mm. Willershausen et al (117) studied the location of root cur-vature in maxillary premolars radiographically and reported that themedian distance from cementoenamel junction to the first curvaturein these teeth ranged from 8.4 to 9.1 mm. Careful analysis of these pa-rameters (angle, radius, length, and location of curvature) is essentialto decrease the risk of procedural errors such as instrument separation,ledge formation, or root perforation during root canal instrumentationor post space preparation.
The relationship between themaxillary posterior teeth and the sur-rounding anatomic structures such as the maxillary sinus and overlyingbone plates should also be considered during dental procedures. Therelationship between the maxillary posterior teeth and the maxillarysinus has been a constant challenge in dentistry, particularly for non-surgical and surgical endodontic procedures (118, 119) or duringextraction of these teeth (120). Furthermore, periradicular and peri-odontal pathosis originating from posterior maxillary teeth may spreadinto the maxillary sinus (121–123). Fortunately, the buccal and palatalroots of the maxillary first premolars have the farthest distance from themaxillary sinus compared with the roots of other maxillary posteriorteeth, with a mean distance of 6.18–8.28 mm and 7.05–7.17 mm,respectively (124, 125). One study (126) evaluated the complicationsthat occurred during apicectomy of maxillary posterior teeth and foundthat maxillary first premolars had the least incidence of sinus perfora-tions (2.0%) compared with maxillary second premolars (10.4%) andmolars (23.0%).
On the other hand, Eberhardt et al (124) found that the meanthickness of bone covering the buccal roots of maxillary posterior teeth
Morphology of Maxillary First Premolars 869
Review Article
was the least over the maxillary first premolars (1.63 � 0.44 mm),whereas the palatal roots of these teeth were covered by the highestthickness of palatal bone (5.42 � 0.86 mm). The thin thickness ofbuccal bone plate is one of the risk factors for developing a clinical con-dition known as mucosal fenestration, which describes the situationwhere the apex of a tooth is exposed to the oral environment afterbreakdown of the overlying bone and alveolar mucosa (127, 128).The presence of this fenestration may give rise to some problemsduring root canal treatment including difficulty in determining theworking length, chronic post-treatment sensitivity to palpation overthe apex, and increased risk of an irrigation accident (129). Many treat-ment modalities have been proposed alone or in combination tomanage mucosal fenestrations including root-end resection, blindroot surface instrumentation and mouth rinsing with chlorhexidine,full-thickness mucogingival flap with primary or secondary healing,full-thickness mucogingival flaps with guided tissue regeneration andbone grafting, and pedicle flap operations (127–129).Some of the anatomic studies investigated the effect of patient’sgender (16, 40, 42, 46, 50–52) and tooth location (48, 50, 51) onthe morphology of maxillary first premolars. Although the toothlocation had no effect on root and canal morphology, significantdifferences related to gender were reported in 2 studies (40, 42).Cheng andWeng (40) found that men had a significantly higher numberof roots than women (66.4% of men had 2-rooted and 3-rooted premo-lars, and 62.7% of women had single-rooted teeth). Ng’ang’a et al (42)reported that men had a significantly higher incidence of 3 root canalscompared with women (11.7% and 1.3%, respectively). None of theprevious studies compared the morphologic features of maxillary firstpremolars in patients with different ethnic backgrounds. Nevertheless, itis interesting to note that the majority of studies that evaluated the Asianpopulations (9, 18, 20, 40, 52, 53) reported a higher incidence ofsingle-rooted premolars (53.6%–76.6%) than those studies conductedon other populations (31.5%–39.5% in North America, 15.5%–46.0%in Europe, 17.9%–45.2% in the Middle East, 8.3% in Australia, and26.7% in Africa). More research is warranted to arrive at definite con-clusions regarding the influence of ethnicity, age, and gender on themorphology of maxillary first premolars. The use of advanced imagingtechniques such as cone-beam computed tomography and micro–computed tomography associated with evaluation of wider populationsby using larger study samples will provide a better insight regardingmorphology of maxillary first premolars and their inherent variations.
Conclusions1. The majority of maxillary first premolars have 1 (41.7%) or 2
(56.6%) roots, and the 3-rooted variant is rare (1.7%).2. Regardless of the number of roots, the majority of maxillary first pre-
molars (86.6%) have 2 root canals.3. The most common root canal configuration in these teeth is type IV
(64.8%), followed by types II and I (13.5% and 11.4%, respectively).4. The clinical case reports showed that the presence of a third root is
the most common anatomic variation in these teeth, whereas devel-opmental anomalies are rare.
5. The clinician should have sound knowledge about the internal andexternal morphology of maxillary first premolars and their relation-ship with adjacent anatomic structures to improve the treatmentoutcome of surgical and nonsurgical dental procedures.
AcknowledgmentsThe authors thank Dr Ziad D. Baghdadi from University
of Saskatchewan, Saskatchewan, Canada and Professor Saad
870 Ahmad and Alenezi
Al-Nazhan from King Saud University, Riyadh, Saudi Arabia fortheir valuable advice and assistance in collecting the literatureused in this study. The authors also thank Engineer Abdullah Bug-shan, Research Chair for Growth Factors and Bone Regeneration(GFBR), Vice Deanship of Research Chairs, at King SaudUniversity for conducting the micro-computed tomographic scanof the teeth in Figures 1 and 2.
The authors deny any conflicts of interest related to this study.
References1. Vertucci FJ. Root canal morphology and its relationship to endodontic procedures.
Endod Topics 2005;10:3–29.2. Cantatore G, Berutti E, Castellucci A. Missed anatomy: frequency and clinical
impact. Endod Topics 2006;15:3–31.3. Friedman S. Prognosis of initial endodontic therapy. Endod Topics 2002;2:59–88.4. Wayman BE, Patten JA, Dazey SE. Relative frequency of teeth needing endodontic
treatment in 3350 consecutive endodontic patients. J Endod 1994;20:399–401.5. Zaatar EI, Al-Kandari AM, Alhomaidah S, Al Yasin IM. Frequency of endodontic
treatment in Kuwait: radiographic evaluation of 846 endodontically treated teeth.J Endod 1997;23:453–6.
6. Pineda F, Kuttler Y. Mesiodistal and buccolingual roentgenographic investigationof 7,275 root canals. Oral Surg Oral Med Oral Pathol 1972;33:101–10.
7. Carns EJ, Skidmore A. Configurations and deviations of root canals of maxillaryfirst premolars. Oral Surg Oral Med Oral Pathol 1973;36:880–6.
8. Vertucci FJ. Root canal anatomy of the human permanent teeth. Oral Surg OralMed Oral Pathol 1984;58:589–99.
9. Walker RT. Root form and canal anatomy of maxillary first premolars in a southernChinese population. Endod Dent Traumatol 1987;3:130–4.
10. P�ecora JD, Saquy P, Sousa Neto M, Woelfel J. Root form and canal anatomy ofmaxillary first premolars. Braz Dent J 1991;2:87–94.
11. P�ecora JD, Sousa Neto M, Saquy PC, Woelfel JB. In vitro study of root canal anat-omy of maxillary second premolars. Braz Dent J 1992;3:81–5.
12. Caliskan MK, Pehlivan Y, Sepetcio�glu F, et al. Root canal morphology of humanpermanent teeth in a Turkish population. J Endod 1995;21:200–4.
13. Kartal N, €Ozcelik B, Cimilli H. Root canal morphology of maxillary premolars.J Endod 1998;24:417–9.
14. Loh H. Root morphology of the maxillary first premolar in Singaporeans. Aust DentJ 1998;43:399–402.
15. Chaparro A, Segura J, Guerrero E, et al. Number of roots and canals in maxillary firstpremolars: study of an Andalusian population. Endod Dent Traumatol 1999;15:65–7.
16. Sert S, Bayirli GS. Evaluation of the root canal configurations of the mandibular andmaxillary permanent teeth by gender in the Turkish population. J Endod 2004;30:391–8.
17. Awawdeh L, Abdullah H, Al-Qudah A. Root form and canal morphology ofJordanian maxillary first premolars. J Endod 2008;34:956–61.
18. Peiris R. Root and canal morphology of human permanent teeth in a Sri Lankanand Japanese population. Anthropol Sci 2008;116:123–33.
19. Weng X-L, Yu S-B, Zhao S-L, et al. Root canal morphology of permanent maxillaryteeth in the Han nationality in Chinese Guanzhong area: a new modified root canalstaining technique. J Endod 2009;35:651–6.
20. Tian YY, Guo B, Zhang R, et al. Root and canal morphology of maxillary first pre-molars in a Chinese subpopulation evaluated using cone-beam computed tomog-raphy. Int Endod J 2012;45:996–1003.
21. Bellizzi R, Hartwell G. Evaluating the maxillary premolar with three canals for end-odontic therapy. J Endod 1981;7:521–7.
22. Sieraski SM, Taylor GN, Kohn RA. Identification and endodontic management ofthree-canalled maxillary premolars. J Endod 1989;15:29–32.
23. Cleghorn BM, Christie WH, Dong CC. Root and root canal morphology of thehuman permanent maxillary first molar: a literature review. J Endod 2006;32:813–21.
24. Barrett M. The internal anatomy of the teeth with special reference to the pulp withits branches. Dent Cosmos 1925;67:581–8.
25. Hess W. The Anatomy of the Root-Canals of the Teeth of the PermanentDentition, Part 1. New York: William Wood and Co; 1925.
26. Okumura T. Anatomy of the root canals. J Am Dent Assoc 1927;14:632–6.27. Mueller AH. Anatomy of the root canals of the incisors, cuspids and bicuspids of
the permanent teeth. J Am Dent Assoc 1933;20:1361–86.28. Green D. Morphology of the pulp cavity of the permanent teeth. Oral Surg Oral Med
Oral Pathol 1955;8:743–59.29. Green D. Stereomicroscopic study of 700 root apices of maxillary and mandibular
posterior teeth. Oral Surg Oral Med Oral Pathol 1960;13:728–33.30. Green D. Double canals in single roots. Oral Surg Oral Med Oral Pathol 1973;35:
689–96.
JOE — Volume 42, Number 6, June 2016
Review Article
31. Hession RW. Endodontic morphology: II—a radiographic analysis. Oral Surg OralMed Oral Pathol 1977;44:610–20.32. Bellizzi R, Hartwell G. Radiographic evaluation of root canal anatomy of in vivo
endodontically treated maxillary premolars. J Endod 1985;11:37–9.33. De Deus QD. Endodontia, 4th ed. Rio de Janeiro: Medsi; 1986.34. Wu Y, Yue B, Shi J. A morphology study on root canal system of 1769 permanent
teeth. J Pract Stomatol 1995;11:98–101.35. Deng D, Zhang M, Wu W. The morphology study of root canal system of permanent
teeth. Sichuan J Anat 2004;12:22–6.36. Oginni A. Clinical radiographic estimation of the number of root canals in
maxillary first and second premolars among Nigerians. Internet J Dent Sci.Available at: http://print.ispub.com/api/0/ispub-article/6583, 2004;2. Ac-cessed July 7, 2015.
37. Lipski M, Wozniak K, Lagocka R, Tomasik M. Root and canal morphology of thefirst human maxillary premolar. Durham Anthropol J 2005;12:2–3.
38. Mattuella LG, Mazzoccato G, Vier FV, S�o MVR. Root canals and apical foramina ofthe buccal root of maxillary first premolars with longitudinal sulcus. Braz Dent J2005;16:23–9.
39. Atieh MA. Root and canal morphology of maxillary first premolars in a Saudipopulation. J Contemp Dent Pract 2008;9:46–53.
40. Cheng X, Weng Y. Observation of the roots and root canals of 442 maxillary firstpremolars. Shanghai Kou Qiang Yi Xue 2008;17:525–8.
41. R�o_zy1o T, Miazek M, R�o_zy1o-Kalinowska I, Burdan F. Morphology of root canals inadult premolar teeth. Folia Morphol (Warsz) 2008;67:280–5.
42. Ng’ang’a R, Masiga M, Maina S. Internal root morphology of the maxillary firstpremolars in Kenyans of African descent. East Afr Med J 2010;87:20–4.
43. Neelakantan P, Subbarao C, Ahuja R, Subbarao CV. Root and canal morphology ofIndian maxillary premolars by a modified root canal staining technique. Odontol-ogy 2011;99:18–21.
44. Rwenyonyi CM, Kutesa A, Muwazi L, Buwembo W. Root and canal morphology ofmaxillary first premolar teeth in a Ugandan population. Open Journal of Stomatol-ogy 2011;1:7–11.
45. Sharma D, Mathur M. A computed tomographic study of canal variations in maxil-lary & mandibular first premolar teeth in Jaipur population: an in vitro study.People J Sci Res 2011;4:1–5.
46. Al-Nazhan S, Al-Daafas A, Al-Maflehi N. Radiographic investigation of in vivoendodontically treated maxillary premolars in a Saudi Arabian sub-population.Saudi Endod J 2012;2:1–5.
47. €Ozcan E, Colak H, Hamidi MM. Root and canal morphology of maxillary firstpremolars in a Turkish population. J Dent Sci 2012;7:390–4.
48. Elkady AM, Allouba K. Cone beam computed tomographic analysis of root andcanal morphology of maxillary premolars in Saudi subpopulation. Egypt Dent J2013;59:3419–29.
49. Kocani F, Kamberi B, Dragusha E, et al. Correlation between anatomy and rootcanal topography of first maxillary premolar on Kosovar population. Open Journalof Stomatology 2014;4:332–9.
50. Ok E, Altunsoy M, Nur BG, et al. A cone-beam computed tomography study of rootcanal morphology of maxillary and mandibular premolars in a Turkish popula-tion. Acta Odontol Scand 2014;72:701–6.
51. Abella F, Teixid�o LM, Patel S, et al. Cone-beam computed tomography analysis ofthe root canal morphology of maxillary first and second premolars in a Spanishpopulation. J Endod 2015;41:1241–7.
52. Dashrath K, Nisha A, Subodh S. Root morphology and tooth length of maxillary firstpremolar in Nepalese population. Dentistry 2015;5:324.
53. Gupta S, Sinha DJ, Gowhar O, et al. Root and canal morphology of maxillary firstpremolar teeth in north Indian population using clearing technique: an in vitrostudy. J Conserv Dent 2015;18:232–6.
54. Barry GN, Heyman R, Fried I. Endodontic treatment of a three-rooted maxillary firstpremolar: case report. N Y State Dent J 1975;41:75–7.
55. Gazit E, Lieberman MA. Upper first premolar with congenitally missing buccal root:a case report. J Endod 1983;9:145–6.
56. Maibaum W. Endodontic treatment of a ‘‘ridiculous’’ maxillary premolar: a casereport. Gen Dent 1989;37:340–1.
57. Zaatar EI, Al-Busairi MA, Behbahani M. Maxillary first premolars with three rootcanals: case report. Quintessence Int 1990;21:1007–11.
58. Augsburger RA, Wong MT. Pulp management in dens evaginatus. J Endod 1996;22:323–6.
59. Nahmias Y, Rampado M. Root-canal treatment of a trifid crown premolar. IntEndod J 2002;35:390–4.
60. Stecker S, DiAngelis AJ. Dens evaginatus: a diagnostic and treatment challenge.J Am Dent Assoc 2002;133:190–3.
61. Soares J, Leonardo R. Root canal treatment of three-rooted maxillary first andsecond premolars: a case report. Int Endod J 2003;36:705–10.
62. Evans M. Combined endodontic and surgical treatment of a three-rooted maxillaryfirst premolar. Aust Endod J 2004;30:53–5.
JOE — Volume 42, Number 6, June 2016
63. �Segovi�c S, Paveli�c B, Juki�c S, Ani�c I. Three-rooted maxillary first premolars: fiveclinical cases. Acta Stomat Croat 2004;38:379–80.
64. Oruco�glu H, Cobankara FK. Maxillary first premolar with three roots: a case report.Hacettepe Dishekimli�gi Fak€ultesi Dergisi 2005;29:26–9.
65. Rekha S, Nadig P, Nadig G. Endodontic treatment of a maxillary first premolar withthree roots: a case report. J Conserv Dent 2005;8:26–9.
66. Woodmansey K. Endodontic treatment of a three-rooted maxillary first premolar: acase report. Gen Dent 2006;5:420–4.
67. Jafarzadeh H. Endodontic treatment of bilaterally occurring three-rooted maxillarypremolars: a case report. N Z Dent J 2007;103:37–8.
68. Parolia A, Kundabala M, Acharya S, Ballal V. Root canal treatment for three-rooted-three canalled maxillary first premolar. Endodontology 2007;19:52–4.
69. Javidi M, Zarei M, Vatanpour M. Endodontic treatment of a radiculous maxillarypremolar: a case report. J Oral Sci 2008;50:99–102.
70. Arisu H, Alacam T. Diagnosis and treatment of three-rooted maxillary premolars.Eur J Dent 2009;3:62–6.
71. Cardinali F, Cerutti F, Tosco E, Cerutti A. Preoperative diagnosis of a third rootcanal in first and second maxillary premolars: a challenge for the clinician.ENDO (Lond Engl) 2009;3:51–7.
72. Dadresanfar B, Khalilak Z, Shahmirzadi S. Endodontic treatment of a maxillary firstpremolar with type IV buccal root canal: a case report. Iran Endod J 2009;4:35–6.
73. Al-Abdulwahhab B, Al-Harthi M, Al-Fayez S, et al. Maxillary first premolar withthree canals: case report. Smile Dent J 2010;5:34–6.
74. FarooqR,MushtaqM, IbrahimM, Purra AR. Endodonticmanagement ofmaxillary firstpremolars with three roots: a report of two cases. Rom J Stomatol 2010;56:297–300.
75. Abraham D, Kumar P. Radiculous premolar. Endodontology 2011;23:95–7.76. Idris M, Sakkir N, Prasad L. Endodontic treatment of a radiculous maxillary pre-
molar: a case report. Journal of Health Sciences and Research 2011;2:17–8.77. Karumaran C, Gunaseelan R, Krithikadatta J. Microscope-aided endodontic treat-
ment of maxillary first premolars with three roots: a case series. Indian J Dent Res2011;22:706–8.
78. Nica L, Ianes C, Florita Z. Root canal treatment of a three-rooted maxillary firstpremolar: a case report. ENDO (Lond Engl) 2011;5:63–6.
79. Aracena D, Beltr�an V, Fuentes R, Borie E. In vitro macroscopic and endoscopicanalysis of three-rooted maxillary premolars and two-rooted mandibular premo-lars in the same individual: a case report. Int J Morphol 2012;30:19–24.
80. Chauhan R, Chandra A. Endodontic management of three-rooted maxillary firstand second premolars: a case report. Gen Dent 2012;59:288–90.
81. Colak H, Aylıkci BU, Keklik H. Dens evaginatus on maxillary first premolar: reportof a rare clinical case. J Nat Sci Biol Med 2012;3:192–4.
82. Gandhi B, Majety KK, Gowdra RH. Root canal treatment of bilateral three-rootedmaxillary first premolars. J Orofac Sci 2012;4:56–9.
83. Garapati S, Raturi P, Chakravarthy K. Maxillary first premolar with three roots: acase report. Heal Talk 2012;5:35.
84. Gupta S, Saxena P, Chandra A. The ‘‘radiculous’’ maxillary first premolar: a rareanatomic variation. Gen Dent 2012;60:178–81.
85. Kamath U, Kamath M, Kusuma S. The identification and endodontic management oftwo ‘‘radiculous’’ maxillary premolars: a challenge for the clinicians. Endodontol-ogy 2012;24:120–4.
86. Nimigean V, Nimigean VR, S�al�av�astruD, Butincu L. A raremorphological variant of thefirst maxillary premolar: a case report. Rom J Morphol Embryol 2013;54:1173–5.
87. Ocak MS, Ahmeto�glu F. Endodontic treatment of three-rooted maxillary first pre-molar: a case report. _In€on€u €Universitesi Sa�glık Bilimleri Dergisi 2013;1:46–8.
88. Oporto V, Saavedra R, Soto P, Fuentes R. Double root anatomical variations in asingle patient: endodontic treatment and rehabilitation of a three-rooted firstpremolar—case report. Int J Morphol 2013;31:45–9.
89. Relvas JBF, de Carvalho FMA, Marques AAF, et al. Endodontic treatment of maxil-lary premolar with three root canals using optical microscope and NiTi rotary filessystem. Case Rep Dent 2013;2013:710408.
90. Sulaiman A, Dosumu O, Amedari M. Maxillary first premolar with three rootcanals: a case report. Ann Ib Postgrad Med 2013;11:105–8.
91. Victorino F, Men-Martins M. Maxillary first premolar with three roots: case report.Dent Press Endod 2013;3:73–7.
92. Chandra S, Mathew S. Endodontic treatment of maxillary ‘radiculous’: a casereport. Endodontology 2014;26:314–6.
93. Gopal S, John G, Pavan Kumar K, et al. Endodontic treatment of bilateral maxillaryfirst premolars with three roots using CBCT: a case report. Case Rep Dent 2014;2014:505676.
94. Jayesh R, Masthan KMK, Nalini A, Aravindha BN. Three rooted maxillary firstpremolar: an unusual occurrence. Research Journal of Pharmaceutical, Biologicaland Chemical Sciences 2014;5:1276–9.
95. Kirilova J, Topalova-Pirinska S, Kirov D. Variation of maxillary first premolar with threeroot canals. Journal of International Medical Association Bulgaria 2014;20:584–8.
96. Mantri V, Palekar A, Kala S. Endodontic treatment of three-rooted maxillary firstpremolar: a case report. J Pierre Fauchard Acad 2014;28:18–22.
Morphology of Maxillary First Premolars 871
Review Article
97. Theruvil R, Ganesh C, George AC. Endodontic management of a maxillary first andsecond premolar with three canals. J Conserv Dent 2014;17:88–91.98. Davoudi A, Akhavan A. Endodontic treatment of maxillary first premolar with three
root canals: a case report. TMU J Dent 2015;2:31–3.99. Mathew J, Devadathan A, Syriac G, Shamini S. Root canal treatment of a maxillary
first premolar with three roots. J Pharm Bioallied Sci 2015;7:746–8.100. Praveen R, Thakur S, Kirthiga M, et al. The radiculous’ premolars: case reports of a
maxillary and mandibular premolar with three canals. J Nat Sci Biol Med 2015;6:442–5.
101. Hamasha A, Alomari Q. Prevalence of dens invaginatus in Jordanian adults. IntEndod J 2004;37:307–10.
102. Darwazeh A, Hamasha A, Pillai K. Prevalence of taurodontism in Jordanian dentalpatients. Dentomaxillofac Radiol 1998;27:163–5.
103. Pillai K, Scipio J, Nayar K, Louis N. Prevalence of taurodontism in premolars amongpatients at a tertiary care institution in Trinidad. West Indian Med J 2007;56:368–71.
104. Gordon MPJ, Chandler NP. Electronic apex locators. Int Endod J 2004;37:425–37.105. Weine FS. The enigma of the lateral canal. Dent Clin North Am 1984;28:833–52.106. van der Sluis LWM, Versluis M, Wu MK, Wesselink PR. Passive ultrasonic irrigation
of the root canal: a review of the literature. Int Endod J 2007;40:415–26.107. Kim S, Kratchman S. Modern endodontic surgery concepts and practice: a review.
J Endod 2006;32:601–23.108. Joseph I, Varma B, Bhat KM. Clinical significance of furcation anatomy of the maxil-
lary first premolar: a biometric study on extracted teeth. J Periodontol 1996;67:386–9.
109. Tamse A, Katz A, Pilo R. Furcation groove of buccal root of maxillary first premo-lars: a morphometric study. J Endod 2000;26:359–63.
110. Katz A, Wasenstein-Kohn S, Tamse A, Zuckerman O. Residual dentin thickness inbifurcated maxillary premolars after root canal and dowel space preparation.J Endod 2006;32:202–5.
111. Lammertyn PA, Rodrigo SB, Brunotto M, Crosa M. Furcation groove of maxillaryfirst premolar, thickness, and dentin structures. J Endod 2009;35:814–7.
112. Al-Shahrani SM, Al-Sudani D, Almalik M, et al. Microcomputed tomographic anal-ysis of the furcation grooves of maxillary first premolars. Ann Stomatol (Roma)2013;4:142–8.
113. Li J, Li L, Pan Y. Anatomic study of the buccal root with furcation groove and asso-ciated root canal shape in maxillary first premolars by using micro–computedtomography. J Endod 2013;39:265–8.
114. BellucciS, Perrini N. A study on the thickness of radicular dentine and cementumin anterior and premolar teeth. Int Endod J 2002;35:594–606.
872 Ahmad and Alenezi
115. Pilo R, Shapenco E, Lewinstein I. Residual dentin thickness in bifurcated maxillaryfirst premolars after root canal and post space preparation with parallel-sideddrills. J Prosthet Dent 2008;99:267–73.
116. Sch€afer E, Diez C, Hoppe W, Tepel J. Roentgenographic investigation of frequencyand degree of canal curvatures in human permanent teeth. J Endod 2002;28:211–6.
117. Willershausen B, Tekyatan H, Kasaj A, Marroqu�ın BB. Roentgenographic in vitroinvestigation of frequency and location of curvatures in human maxillary premo-lars. J Endod 2006;32:307–11.
118. Watzek G, Bernhart T, Ulm C. Complications of sinus perforations and their man-agement in endodontics. Dent Clin North Am 1997;41:563–83.
119. Hauman C, Chandler N, Tong D. Endodontic implications of the maxillary sinus: areview. Int Endod J 2002;35:127–41.
120. Nedbalski TR, Laskin DM. Use of panoramic radiography to predict possible maxil-lary sinus membrane perforation during dental extraction. Quintessence Int 2008;39:661–4.
121. Selden HS. Endo-antral syndrome and various endodontic complications. J Endod1999;25:389–93.
122. Lu Y, Liu Z, Zhang L, et al. Associations between maxillary sinus mucosal thickeningand apical periodontitis using cone-beam computed tomography scanning: aretrospective study. J Endod 2012;38:1069–74.
123. Phothikhun S, Suphanantachat S, Chuenchompoonut V, Nisapakultorn K. Cone-beam computed tomographic evidence of the association between periodontalbone loss and mucosal thickening of the maxillary sinus. J Periodontol 2012;83:557–64.
124. Eberhardt JA, Torabinejad M, Christiansen EL. A computed tomographic study ofthe distances between the maxillary sinus floor and the apices of the maxillary pos-terior teeth. Oral Surg Oral Med Oral Pathol 1992;73:345–7.
125. Von Arx T, Fodich I, Bornstein MM. Proximity of premolar roots to maxillary sinus:a radiographic survey using cone-beam computed tomography. J Endod 2014;40:1541–8.
126. Freedman A, Horowitz I. Complications after apicoectomy in maxillary premolarand molar teeth. Int J Oral Maxillofac Surg 1999;28:192–4.
127. Ju Y-R, Tsai A, Wu Y-J, Pan W-L. Surgical intervention of mucosal fenestration in amaxillary premolar: a case report. Quintessence Int 2004;35:125–8.
128. Chen G, Fang C, Tong C. The management of mucosal fenestration: a report of twocases. Int Endod J 2009;42:156–64.
129. Vertucci F, Haddix J. Tooth morphology and access cavity preparation. In:Hargreaves KM, Cohen SF, eds. Pathways of the Pulp. St Louis: Mosby; 2010:182–4.
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