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Root and Root Canal Morphology of the HumanPermanent Maxillary First Molar: A Literature ReviewBlaine M. Cleghorn, DMD, MS, William H. Christie, DMD, MS, FRCD(C), and Cecilia C.S. Dong, DMD, BSc (Dent), MS, FRCD(C)
AbstractThe objec�ve of this study was to review the literature with respect to the root and canal systems in the maxillary first molar. Root anatomy studies were divided into laboratory studies (in vitro), clinical root canal system anatomy studies (in vivo) and clinical case reports of anomalies. Over 95% (95.9%) of maxillary first molars had three roots and 3.9% had two roots. The incidence of fusion of any two or three roots was approximately 5.2%. Conical and C-‐shaped roots and canals were rarely found (0.12%). This review contained the most data on the canal morphology of the mesiobuccal root with a total of 8399 teeth from 34 studies. The incidence of two canals in the mesiobuccal root was 56.8% and of one canal was 43.1% in a weighted average of all reported studies. The incidence of two canals in the mesiobuccal root was higher in laboratory studies (60.5%) compared to clinical studies (54.7%). Less varia�on was found in the distobuccal and palatal roots and the results were reported from fourteen studies consis�ng of 2576 teeth. One canal was found in the distobuccal root in 98.3% of teeth whereas the palatal root had one canal in over 99% of the teeth studied. (J Endod 2006;32:813–821)
Key Words
ENDO ACADEMYMay, 201
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AbstractThe aim of this study was to evaluate the effect of cavity design and glass fiber posts on stress distribu�ons and fracture resistance of endodon�cally treated premolars. Fi�y extracted intact mandibular premolars were divided into 5 groups (n=10): ST, sound teeth (control); MOD, mesio-‐occlusal-‐distal prepara�on + endodon�c treatment (ET) composite resin restora�on (CR); MODP, mesio-‐occlusal-‐distal + ET + glass fiber post CR; MOD2/3, mesio-‐occlusal-‐distal two thirds occlusal-‐cervical cusp loss + ET CR; and MODP2/3, mesio-‐occlusal-‐distal two thirds cusp loss + ET + glass fiber post CR. The specimens were loaded on a cusp slope un�l fracture. Fracture pa�erns were classified according to four failure types. Stress distribu�ons were evaluated for each group in a twodimensional finite element analysis. The fracture resistance of the MODP, MOD2/3, and MODP2/3 groups was significantly lower than the ST and MOD groups (p<0.05). The loss of dental structure and the presence of fiber post restora�on reduced fracture resistance and created higher stress concentra�ons in the tooth-‐restora�on complex. However, when there was a large loss of dental structure (MODP2/3), the post reduced the incidence of catastrophic fracture types. (J Endod 2008;34:1015–1019)
The Influence of Cavity Design and Glass Fiber Postson Biomechanical Behavior of Endodontically Treated PremolarsCarlos Jose Soares, DDS, MS, PhD, Paulo Vinicius Soares, DDS, MS, et al
May, 201
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Abstract Residual den�n thickness in 25 extracted bifurcated maxillary premolars a�er canal and Parapost prepara�on was assessed using acrylic muffle, a�er embedding in polyester resin and sec�oned horizontally. A�er each procedure, the residual den�n thickness was compared to the original den�n thickness at eight aspects in three root levels. Residual den�n thickness measurements were calculated using photographs and a Digi�zer. In the lingual aspect, the original den�n thickness averaged 0.99 mm (coronal slice) and 0.78 mm (middle slice). Den�n removal a�er dowel prepara�on was 31%. Three-‐way ANOVA with repeated measures was used. The difference in residual den�n thickness was highly significant regarding procedure (canal and dowel prepara�on, p <0.0001), slice (middle, coronal, p <0.0001), and the eight aspects (p <0.0001). This in vitro study emphasizes the minimal den�n width of the buccal root, especially towards the bifurca�on. Thus, dowels should be avoided in this root. (J Endod 2006; 32:202–205)
Residual Dentin Thickness in Bifurcated MaxillaryPremolars After Root Canal and Dowel Space PreparationAlexander Katz, DMD, Silvia Wasenstein-Kohn, DMD, Aviad Tamse, DMD, and Ofer Zuckerman, DMD
May, 201
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in Response to Pathologic Conditions and Treatment Procedures Domenico Ricucci, MD, DDS, and Jose´ F. Siqueira Jr, DDS, MSc, PhD
AbstractIntroduc�on: This ar�cle reviews and reports on the histopathologic and histobacteriologic status of the �ssue in lateral canals and apical ramifica�ons (LC/AR) in diverse clinical condi�ons as well as in response to endodon�c treatment. Methods: In total, serial sec�ons from 493 human tooth specimens obtained by extrac�on or apical surgery were screened for the presence of LC/ AR. Results: LC/AR were observed in about 75% of the teeth. In clinically vital teeth, vital �ssue was consistently found in LC/AR. In teeth with periodontal disease, the whole pulp became necro�c only when the subgingival biofilm reached the main apical foramen. In teeth with pulp exposure by caries, the �ssue in LC/AR remained vital as far as the pulp �ssue in the main canal did so. When pulp necrosis reached the level of the LC/ AR, the �ssue therein was either par�ally or completely necro�c. Chemo-‐mechanical prepara�on par�ally removed necro�c �ssue from the entrance of LC/AR, whereas the adjacent �ssue remained inflamed, some�mes infected, and associated with periradicular disease. Vital �ssue in LC/AR was not removed by prepara�on. In cases in which lateral canals appeared radiographically ‘‘filled,’’ they were actually not obturated, and the remaining �ssue in the ramifica�on was inflamed and enmeshed with the filling material. Conclusions: Overall, the belief that lateral canals must be injected with filling material to enhance treatment outcome was not supported by literature review or by our histopathologic observa�ons. It appears that strategies other than finding a technique that be�er squeezes sealer or gu�a-‐percha within LC/AR should be pursued to effec�vely disinfect these regions. (J Endod 2010;36:1–15)
A 5 Yr Clinical Investigation of Second Mesiobuccal Canals in Endodontically Treated and Retreated Maxillary Molars James Wolcott, DDS, Dave Ishley, DDS, MS, et al
AbstractAn examina�on of 5616 endodon�cally treated and retreated maxillary first and second molars was made in an a�empt to determine the percentage of MB2 canals that could be located rou�nely, and evaluate if there were any significant differences between ini�al treatments and retreatments. The teeth examined were 3578 first molars and 2038 second molars treated consecu�vely over a 5-‐yr period by six endodon�sts. Overall the MB2 canal was found in 2133 (60%) first molars, and 712 (35%) second molars. The incidence of a MB2 canal in first molar retreatments was 66% compared to a 58% incidence in ini�al treatments. Whereas in second molars the retreatment incidence was 40% compared to 34% in ini�al treatments. The significant difference in the incidence of a MB2 canal between ini�al treatments and retreatments suggests that failure to find and treat exis�ng MB2 canals will decrease the long-‐term prognosis.
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Abstract Informa�on concerning the anatomy of the physiological foramen is limited. The aim of this study was to inves�gate the distance between the physiological and anatomical apex, accessory foramina frequency, and the shape and diameter of the physiological foramen in maxillary and mandibular molars. The apical anatomy of 523 maxillary and 574 mandibular molars from an Egyp�an popula�on was inves�gated by means of a computeraided stereomicroscope (40 magnifica�on). The following results were obtained: (a) There was a high percentage of two physiological foramina in mesial (87.06%) and mesiobuccal (71.15%) roots of mandibular and maxillary first molars, respec�vely. (b) There
was a high frequency of accessory foramina in maxillary mesiobuccal (33%) and mandibular mesial (26%) roots. (c) The most common physiological foramen shape was oval (70%). (d) The mean of the narrow and wide physiological foramen diameters was as follows: • 0.20 to 0.26 mm in mandibular molars • 0.18 to 0.25 mm in the maxillary mesiobuccal and distobuccal root • 0.22 to 0.29 mm in the maxillary palatal root.
Morphology of the Physiological Foramen:I. Maxillary and Mandibular Molars
Brita Willershausen-Zo¨ nnchen, Prof. Dr. med.dent.
May, 201
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AbstractMandibular molars can have an addi�onal root located lingually (the radix entomolaris) or buccally (the radixparamolaris). If present, an awareness and understanding of this unusual root and its root canal morphology can contribute to the successful outcome of root canal treatment. This report discusses endodon�c treatment of three mandibular molars with a radix entomolaris or paramolaris, both of which are rare macrostructures in the Caucasian popula�on. The prevalence, the external morphological varia�ons and internal anatomy of the radix entomolaris and paramolaris are described. Avoiding procedural errors during endodon�c therapy demand an adapted clinical approach to diagnosis and root canal treatment. (J Endod 2007;33:58 –63)
The Radix Entomolaris and Paramolaris:Clinical Approach in EndodonticsFilip L. Calberson, DDS, MMS, Roeland J. De Moor, DDS, MMS, PhD, and Christophe A. Deroose, DDS, MMS