ORIGINAL ARTICLE

Histomorphometrical and radiological comparisonof low-level laser therapy effects on distraction osteogenesis:experimental study

Bahadir Kan & Ferda Tasar & Petek Korkusuz &

Orkun Ersoy & Alper Cetinkaya & Cagla Z. Gur &

Hamdi Celik & Gokce Meral

Received: 2 August 2012 /Accepted: 12 March 2013 /Published online: 19 April 2013# Springer-Verlag London 2013

Abstract Distraction osteogenesis (DO) is the application oftraction to the callus formed between bone segments andstimulation of bone formation by creating stress on the calluswith this traction. Shorten the duration of DO and increasingthe capacity of bone formation is important to prevent thepossible complications of DO. For this reason, it was consid-ered that low-level laser therapy (LLLT) may affect positively

DO and it can decrease the complication range by shorteningthe period. Unilateral mandibular distractors were applied on16 female white New Zealand rabbit to prove this hypothesiswith micro CT, plain radiograph and histomorphometric anal-yses. Eight rabbits were applied LLLT with GaAlAs laser onthe distraction area during the distraction period. On the post-distraction 28th day, four rabbits from study group and fourrabbits from control groups were sacrificed. The rest of therabbits were sacrificed on post-distraction 56th day. As a resultof this study, significant positive effects of LLLT on post-distraction 28th day were revealed with all analyses. Inhistomorphometrical analyses, new bone formation was sig-nificantly higher in short-term laser applied group comparingto that of short-term control group (p=0.029). In bothmicroCTand plain radiograph, the highest radioopacity valueswere observed in short-term laser group when compared withthat of the controls (p=0.043 and p=0.025, respectively).Even though LLLT increased the healing capacity on short-term, it was not sufficient on long-term (post-distraction 56thday) healing. LLLT application on distraction period, activatehealing on bone so it may decrease DO period. The result ofthis study should be supported with clinical studies and themost effective laser source, dose and application time shouldbe revealed with experimental and clinical studies.

Keywords Distraction osteogenesis . Low level lasertherapy . Bone . Rabbit . Mandible

Introduction

Distraction osteogenesis (DO) is the application of traction tothe callus formed between bone segments and stimulation ofbone formation by creating stress on the callus with thistraction [1]. There are definite risks/complications that can

B. Kan (*)Faculty of Dentistry, Department of Oral and MaxillofacialSurgery, Kocaeli University, Yuvacik Campus P.C,41900, Basiskele, Kocaeli, Turkeye-mail: bahadirkan@gmail.com

F. TasarFaculty of Dentistry, Department of Oral and MaxillofacialSurgery, Hacettepe University, Ankara, Turkey

P. KorkusuzFaculty of Medicine, Department of Histology and Embryology,Hacettepe University, Ankara, Turkey

O. ErsoyFaculty of Geological Engineering, Departmentof Mineralogy-Petrogrphy, Nigde University, Nigde, Turkey

A. CetinkayaFaculty of Medicine, Medical and Surgical Research Lab,Hacettepe University, Ankara, Turkey

C. Z. GurNanotechnology and Nanomedicine Division, Instituteof Science, Hacettepe University, Ankara, Turkey

H. CelikFaculty of Medicine, Department of Anatomy,Hacettepe University, Ankara, Turkey

G. MeralDepartment of Dentistry, Acibadem Kozyatagi Hospital,Istanbul, Turkey

Lasers Med Sci (2014) 29:213–220DOI 10.1007/s10103-013-1308-3

arise in distraction process such as infection, malunion,ununion, lack of patient cooperation as a result of social andfunctional restrictions and fracture of distractor components[2]. There are some experimental studies to prevent or reducethese situations by shortening the treatment period and increas-ing osteogenic capacity [3]. Biostimulative effect of low-levellaser therapy (LLLT) is one of these supportive treatments.

LLLT, which accelerates soft and hard tissue healing ininjuries, is an effective and contemporary method for clini-cians. LLLT’s positive effects on nerve cell healing, newcapillary formation, RNA and DNA production, fibroblastto myofibroblast transformation, proliferation of bone cellsand new bone formation have been proved with variousstudies performed in recent years [4]. Despite the fact thathelium–neon laser was the first source used in this manner,galium–aluminium–arsenite lasers (GaAlAs) have latergained popularity owing to their deep penetration powerand significant biostimulative effects.

Although there are a few studies about LLLT effects ondistraction healing, these studies are not comprehensiveenough. In most of these articles, the numbers of subjectsare not adequate for a statistical result and the examinationmethods are not objective. In our research, distraction osteo-genesis, which is a contemporary approach in reconstructionof hard and soft tissue defects in facial and dentoalveolarregions, was supported with GaAlAs laser and possible pos-itive effects of LLLT application during distraction periodwere comparatively assessed via histomorphometric analyses(gold standard for bone healing studies), microtomographicanalyses (new and detailed radiographic examination method)and plain radiographic analyses (standard examination meth-od in clinical application of DO). This research is the mostdetailed and comprehensive study about LLLT effects ondistraction osteogenesis ever published. In addition, weresearched efficiency of LLLT with total 45 J energy that ismuch lower than LLLT doses of previous studies similar tothis research.

Materials and methods

This is an experimental randomised prospective study and 16female New Zealand white rabbits were selected for the studyfollowing the approval of Hacettepe University Ethical Com-mission Local Ethical Committee of Animal Research (Meet-ing number, 2009/10; Permission number, 2009/49-1) and alloperations were performed in Hacettepe University MedicalResearch Centre Animal Laboratory.

Standard protocol

Animals were caged separately and fed ad libitum. Afterquarantine period (15 days), rabbits were taken under

anaesthesia with 5 mg/kg xylazin (Alfazyne® I.M. Alfasanİnt. B.V. Woerden, Nederland) followed with 35 mg/kgKetamin HCL (Alfamine® I.M. Alfasan İnt. B.V. Woerden,Nederland) IM 5 min after initial xylazin injection. Afterpreparing the operation sites under aseptic conditions, 1 ccof subcutaneous local anaesthesia (Maxicaine® VEMDrugs, Ankara, Turkey) was administered around the pre-planned incision area. Mandible was accessed via dissectionafter a 2.5-cm-long skin incision performed on the mandib-ular basis (Fig. 1a,b). Vertical osteotomy, which was anteriorto the molar teeth and posterior to the mental foramina, wasplanned and performed using a steel separator under contin-uous saline irrigation (Fig. 1c). Bone segments were totallyseparated using an osteotome. Specially designed and pro-duced distractors for rabbit mandibles were placed and fixedto each side of osteotomy with two or three titanium micro-screws of 7 mm length and 1.5 mm diameter (Fig. 1d). Afterfixation, the distractor was checked for activation and thesurgical area was closed primarily with 4.0 vicryl suture. Allanimals were followed up until they fully recovered fromanaesthesia. Following the surgery, the rabbits were given50 mg/kg ceftriaxone disodium IM (Cefaday®, i.m.Biofarma, Istanbul, Turkey) as antibacterial regime and PO60 mg/kg acetaminophen (Volpan®, Hüsnü Arsan Drugs,Istanbul, Turkey) as analgesic regime for 4 days.

On the post-operative 6th day, the device was lengthened1 mm per day for 6 days. Twenty-eight- and 56-days-long“latency periods” were observed prior to the consolidationperiod. Sixteen animals were allocated to one of four groups(group A-L, 28 days consolidation with LLLT; group A-K,28 days consolidation without LLLT; group B-L, 56 daysconsolidation with LLLT; group B-K, 56 days consolidationwithout LLLT) and each group included four rabbits. Follow-ing the distractors activation, rabbits in groups A-L and B-Lwere irradiated with GaAlAs laser after every distraction (XD-2 with R24-B handpiece, Fotona, Ljubljana, Slovenia).

Immediately after each device’s activation, the laser groups(A-L and B-L), chosen randomly, were treated with a GaAlAslaser (R24-B handpiece, Fotona XD-2, Ljubljana, Slovenia) of808 nm and an output of 0.25W, 5 s on each point with 6 mmspot size (7.5 J energy everyday—end of six days total 45 Jenergy)—six transmucosal sites on the buccal and lingualaspects of the area around the distraction gap (three sites onbuccal, three sites on lingual aspects). Special attention waspaid to perform LLLT in equal time intervals with equaldurations. This application was performed for 6 days duringwhich the distractor was activated, at the same time of the dayand under same conditions.

The animals were sacrificed with high-dose xylazine andketamine injection immediately after completion of the con-solidations periods (post-consolidation 28th and 56th days).The samples were fixed with formalin solution as soon asthey were obtained.

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Microtomographic analysis

Three-dimensional radiological volumetric analysis ofthe samples was performed with micro-tomography de-vice (SkyScan 1174; SkyScan Micro-CT, Kontich, Bel-gium). Size of the bone samples was minimised with asteel separator under saline irrigation without giving anyharm to distraction area. Each sample was irradiatedwith 50 kV and 800 uA settings for 52 min. Duringscanning, the bone was placed and stabilised into aplastic cup of formalin solution. Digitalised views ofsamples were transferred to the computer connected tomicroCT and the pictures were saved as “raw data” in“tif” formation. Three-dimensional and later horizontalviews of the bones’ raw data were obtained with CT-Vol(SkyScan, Kontich, Belgium) computer programme. Theartefacts, which resulted due to shooting characteristicof the tomography device and scanning in formol, weredecreased via same programme. Distraction area wasdrawn on the horizontal sections and saved as distrac-tion ROI (region of interest). A control ROI in healthybone next to the distraction zone, which was least likelyto be affected by the artefacts, was drawn for studyscores. Percentage of previously determined rabbit man-dible density values (30–225 HU) in both control anddistraction ROI areas were calculated. Then differencebetween control ROI percentage and distraction ROIpercentage (% control ROI−% distraction ROI) wassaved as micro-tomographic analysis score. With sucha procedure, level of bone density in the distractionzone in comparison to the normal bone density wasevaluated.

Plain radiographic analysis

All specimens were placed on a lung radiograph with equalinterval. An aluminium stepwedge that consists of ten stepswith 1 mm thickness was positioned on the centre of thefilm. The bones were irradiated with a digital radiographydevice (Axiom Aristos MX-VX, Siemens, Erlangen, Ger-many) on 48 kW and 2 mA/sn setting. The picture weresaved and transferred to a computer as jpeg. Mean greydensity values of each step of the aluminium stepwedgeand distraction areas were assessed and analysed withImageJ. The grey density values of the distraction areaswere matched with the stepwedges’ and thickness of thematched step were saved as the score.

Histology and histomorphometry

After radiologic imaging, all specimens, fixed in 10 % neu-tral buffered formalin at room temperature, were decalcifiedin De Castro solution [5] (chloral hydrate, nitric acid anddistilled water) and embedded in paraffin by using an auto-mated tissue processor with vacuum; 3–5-μm-thick sectionswere stained with hematoxylin and eosin (HE), Mallory’strichrome (MT). MT produces high contrast images with redbone, blue osteoid-collagen and purple cell cytoplasm. Pho-tomicrographs of each distraction area were generated by alight microscope (Leica DMR) attached computerised digi-tal camera (Model DFC 480 Leica, Westlar, Germany).Bright-field images of the distraction area were capturedand analysed quantitatively by image processing program(Qwin Plus, Leica Inc., Westlar, Germany). Number ofpixels corresponding to new trabecular bone area in each

Fig. 1 a Submandibularincision application with facialarterial protection, b accessingto the mandible without givingany harm to the mental nervebundle while dissection. cOsteotomy line positionedbehind the mental nerve andfront of molar teeth. dDistractor was fixed to thesegments with titanium screws

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image of distraction zone was quantified, divided by thetotal number of pixels corresponding to total distractionzone and converted to square micrometers in each specimen.Osteoblasts were quantified based on their morphology onHE-stained sections. High-power fields presenting newbone forming areas were randomly selected on the distrac-tion zone. The osteoblasts were quantified for the length oftheir linear apposition along osteoid-new bone surfaces rel-ative to total new bone-osteoid length for three randomlyselected high power fields (×200) and are reported as afraction (%) average for each sample. New blood vesselswithin the distraction zone were similarly digitally countedat four randomly selected high-power fields (×200) and arereported as average for each sample.

Statistical analysis

Statistical analyses were conducted using SPSS 12.0 forWindows (SPSS Inc., Chicago, IL). Independent variableswere the groups and the dependent variables were the his-tology, X-ray and micro-CT parameters. The normality ofdistribution and the homogeneity of variances of the samplewere established using the Shapiro–Wilk test. All parame-ters were analysed by nonparametric tests Mann–WhitneyU. All data were represented with mean, variant, standarddeviation, minimum, maximum and range values. The dif-ference was considered significant if p<0.05.

Results

Microtomographic analysis

Bony filling of the distraction gap was observed in allspecimens. The osteotomy and distraction lines were notseen clearly on the laser applied specimens (groups A-Land B-L). The density percentage of 30–225 HU of thenewly formed bone in the distraction zones were observedas very proximate to the host bone’s density values(Table 1).

The comparison of the ROI values of the control anddistraction groups revealed a statistically significant differ-ence between the groups A-L and A-K (p=0.043). Further-more, a more evident zone of radioopacity more proximate

to the host bone’s radioopacity values was formed in spec-imens of group A-L when compared with specimens in the“control” group A-K.

Plain radiographic analysis

Computation results obtained via conventional radiographyis listed in Table 2. When radiographs were assessed, asignificant radioopacity in close proximity to the host bonesradioopacity was observed in specimens of the group A-L.Osteotomy lines were not evident. Statistical findings of theanalysis performed showed that the grey value differencesbetween short-term laser and short-term control were signif-icant on behalf of the study group (p=0.025). Althoughgroup B-L scores were higher than that of group B-K, itwas not reflected by statistical analyses (p=0.544). Whilethe scores differences of laser groups in itself (groups A-Land B-L) were statistically significant (p=0.025), the ana-lyse result of control groups in itself had no statisticaldifferences (p=0.881; Table 2).

Histology and histomorphometry

The distraction osteogenesis process followed generallyintramembranous ossification steps in all groups. Thefibrovascular distraction zone exhibited a relatively bet-ter organised environment in laser applied groups com-paring to that of the control. The bone regenerationoccurred from the periphery (distraction edges) to thecentral direction reflecting a healthy osteogenesis withinthe distraction zone in all groups. The new bone pertotal defect area ratio was significantly higher in short-time laser applied group comparing to that of short-termcontrol group (p=0.029). The osteoblast-lined activebone length and the blood vessel density were higherin short-term laser applied group comparing to those ofthe control but the differences were not statisticallysignificant; probably due to the limited numbers of thegroups (p=0.083 in each parameter). According to thisdata new bone formation within the distraction zonewas significantly accelerated in short-term laser appliedgroup. The long-term laser and long-term control groupsdid not show any statistically significant difference re-garding the histologic healing parameters. This means

Table 1 Statistical values of theobtained micro-tomographic as-sessment scores

Mean Variance Standard deviation Minimum Maximum Range

Group A-L 2.5661 51.951 7.20769 −7.04 10.42 17.46

Group A-K 29.7459 514.206 22.67610 5.30 59.15 53.85

Group B-L 11.8959 62.672 7.91655 0.96 19.61 18.65

Group B-K 27.7467 568.194 23.83682 10.12 60.63 50.51

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that the laser application has no significant effect whenused as long-term therapy protocol. On the other handthe distraction osteogenesis is significantly promoted byshort-term laser therapy. (Fig. 2; Tables 3, 4 and 5).

Discussion

Along with the positive findings of contemporary studiescarried out on LLLT’s effects on healing periods of both hard

Table 2 Definitive statisticalresults of the obtained conven-tional radiograph scores

Mean Variance Standard deviation Minimum Maximum Range

Group A-L 5.75 0.25 0.5 5 6 1

Group A-K 3.25 1.583 1.25831 2 5 3

Group B-L 3.75 0.917 0.95743 2 5 3

Group B-K 3.25 0.917 0.95743 2 4 2

Fig. 2 a The distractionosteogenesis followsintramembranous ossificationsteps in all groups (a–f) inwhich the distraction zone isfilled with a fibrovascular tissueand bony trabecules. Note thatdistraction zone is relativelybetter organised in (c–f). Theossifying active bone trabeculesare more pronounced andthicker in short-term laser group(c and d) comparing to the othergroups. DZ distraction zone,DE distraction edge, TBtrabecular bone, HEhematoxylin and eosin, MTMallory’s trichrome

Lasers Med Sci (2014) 29:213–220 217

and soft tissues, this method has gained popularity in regen-erative medicine and dentistry [6]. In our study, it was clearlyseen in all analyses that LLLTapplication with a GaAlAs laser(0.25 w power, 5 s in per point, totally 6 points) was signif-icantly promoted the healing on post-distraction 28th day butthis effect was not valid for the post-distraction 56th day thatwas the long-term day of the study. Histomorphometric anal-ysis in particular, provided statistically significant results ofLLLT’s positive effect only on short-term healing of increasein new bone trabeculation. In addition, an increase—statisti-cally not significant—in short-term vascularisation and activeosteoblast fields in comparison to the control group wasevaluated. The microtomographic analysis, which is a distinc-tive and original parameter of our study, have provided statis-tically significant findings of ROI density values of short-termlaser group and short-term control group. Similar boneradioopacity values obtained in short-term laser groupwhen compared to the host bone proved positive effectsof LLLT on DO regeneration with three-dimensionalradiographic imaging.

LLLT procedure of which positive effects on the healing ofhard and soft tissues are reported in the literature has also beensubject to many researches in regard to its effectiveness ondistractor studies performed on various models [6–10].Cerqueira et al. [9] investigated the effects of LLLTapplicationon different stages of distraction osteogenesis and their studycarried out on sheepmandibles. The studywas performedwiththree groups; LLLT application during the activation period,LLLT application during the consolidation period and thecontrol group. Subjects were bio-stimulated with a GaA1Aslaser of 830 nm wavelength, 80 J in total. Histological evalu-ation results obtained from the cross-sections of the 21st dayrevealed more new trabecular bone formation in laser-appliedgroups. It is clear that laser energy positively affect thedistractor gap healing after the LLLT application procedurein activation period and our results are parallel to the otherstudies. In histological examinations, more regular

cartilaginous healing in laser groups is common in these tworesearches. Kreisner et al. [8] reported positive effects of LLLTapplication on new bone formation in the wake of their studyperformed on ten rabbits (six of which were applied LLLT).Hübler et al. [10] investigated the chemical compositions ofbone (Ca and P values) with X-ray fluorescence spectroscopyand X-ray diffraction and reported positive effects of LLLTonnewly formed bone’s bio-modulation after their study carriedout on five rabbit mandibles (three of which were appliedLLLT) and they reported that LLLT was effective in earlyhealing stage. But the number of subject used in this study isnot adequate for statistical significance. These studies havecapacity to be a preliminary study for extensive studies andthese studies published before our study provided us to inves-tigate the effectiveness of LLLTon DO with more quantitativeanalyses. The most comprehensive of limited number of stud-ies relative to the effects of LLLT on DO is Miloro et al.’s [7]study which was carried out on nine rabbit mandibles withbilaterally placed distractors (experimental and control sites onthe same animal). In this study unlike the conventional Ilizarovdistraction method, following the latent period of 1 day,distractors were activated 1 mm per day, for 10 days. Distrac-tion zones of the rabbit mandibles were applied LLLT withGaA1As laser (820 nmwavelength, 400 mWoutput power) inevery session distractors were activated. Thereaftersacrification histomorphometric and radiologic investigationstogether with mechanical analysis were carried out. Semi-quantitative radiological and mechanical analysis’ scores indi-cate that bone healing obtained with LLLT was more rapidthan the control groups’ healing scores. A histologically sig-nificant increase in trabeculation and bone formation particu-larly in LLLT applied 4 weeks consolidation group has beendetermined and it is parallel to our results but technical differ-ences should be considered. In this study, the successful me-chanical result is also a sign of positive clinical efficiency ofLLLT. In our study, due to ethical limitations andhistomorphometrical analyses after radiological examinations

Table 3 Statistical values ofnew trabecular bone scoresobtained withhistomorphometric analyses

Mean Variance Standard deviation Minimum Maximum Range

Group A-L 0.23 0.002 0.04963 0.18 0.28 0.1

Group A-K 0.1279 0.002 0.04075 0.08 0.17 0.09

Group B-L 0.3459 0.006 0.07592 0.23 0.40 0.16

Group B-K 0.2625 0.26 0.16082 0.14 0.49 0.35

Table 4 Statistical values of theosteoblast-lined active bonelength

Mean Variance Standard deviation Minimum Maximum Range

Group A-L 31.3750 27.463 5.24047 25.30 37.2 11.9

Group A-K 19.9750 60.969 7.80828 13.6 31.10 17.50

Group B-L 38.7750 266.883 16.33654 21.10 59.20 38.10

Group B-K 33.9250 157.769 12.56062 21.10 51.20 30.10

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(because mechanical test damages the samples), we could notprefer mechanical test.

Detailed quantitative analyses were given preference toobtain groups and parameters when LLLT effects on DO areinvestigated in our study, when compared with other studies.In our research, main assessment technique is thehistomorphometric evaluation. By utilizing such a tech-nique; newly formed bone and areas of continuingmineralisation could be assessed and also the vascularisationof the distraction zone in particular could be clearly evalu-ated in detail. For the assessment of obtained specimensduring histologic sampling; widely valued techniques inclinical distraction applications such as plain radiographyand microtomography, which is regarded as a contemporarytechnique in experimental studies of three-dimensional eval-uations, were also utilised. This way detailed and compara-tive assessments of the specimens were made possible. Nomicrotomographic analysis supported study on the effects ofLLLT on DO could be achieved in our literature research.

In line with these analysis and assessments, LLLT appli-cation during the consolidation period was determined toincrease bone formation in the distraction zone and providesufficient healing in a shorter period of time (28 days).These findings are in accordance with literature [7, 9, 10].LLLT’s positive effects in short term have also beensupported with original in vivo and in vitro studies in theliterature [11–13]. It is known that the healing period whenthe biostimulation was carried out as well as the level ofapplied laser was of significant importance in laserbiostimulation. Effects of LLLT application on cell activitiesin particular (differentiation and proliferation) were reportedto be more beneficial when mineralised areas displayed lesspositive findings making it clear on a cellular basis whyLLLT was more effective in short-term healing [13]. Thissituation was also supported with other studies [14–16].

The meaning and importance of vascularisation innew bone formation together with distraction area’sblood vessel capacity and its correlation with new boneformation should be valued [17–19]. Garavello et.al.[20]applied biostimulation with He-Ne laser (633 nm wavelength, 1 mW output power) on defects they preparedon rat tibias with burs to evaluate LLLT’s effects onangiogenesis in bone healing. In the result they reporteda significant regression in laser applied groups in timewhich is thought to be an inhibitor effect. In a different

study of theirs, performed with a similar procedure(same method and laser doses), Garavello-Freitas et.al.[21] investigated the effects of LLLT on bone formationand reported concordant findings of decreasing trabecu-lar bone ratio due to laser’s inhibitor effect in the longterm. As a common result of both their studies, theyreported an inhibitor effect of LLLT application viadecreasing matrix synthesis and angiogenesis on the15th day of the treatment as well as inhibiting thesecretion of vascular growth factor during boneremodelling. In our study, even though the blood vesselcount on the distraction area of short-term laser groupwas relatively higher when compared with short-termcontrol, this difference was not statistically significant(p=0.083). However, such a difference can be regardedas statistically significant given the fact that the study iscarried out with higher numbers of samples in eachgroup. In addition, a statistically significant decrease invascularisation was observed in the long term whengroups of both short- and long-term LLLT applied groupswere compared (p=0.043). These findings also correlate withliterature and strengthen the idea that LLLT application cancreate an inhibitor effect on the long term [21, 22].

In accordance, our study’s conventional radiographic andmicrotomographic findings indicated the efficacy of LLLTon short-term consolidation. The comparison of LLLT ap-plied group during short-term consolidation (group A-L)with its own control group (group A-K) and the long-termconsolidation group (group B-L), revealed statistically sig-nificant results. Radiographic analysis of the group A-L inparticular, revealed results strongly parallel to those of thehistomorphometric analysis. Termination of the consolida-tion period in clinical applications is ordinarily determinedaccording to the findings of conventional radiographic eval-uations. Stability of the plain radiograph was also tested inthis study. Despite similar short-term findings of microCTand plain radiograph, long-term results revealed a margin oferror which is in accordance with the literature where extracare is attached importance in clinical applications whendetermining new bone formation. In the literature itwas stated before that microCT was more effective andsuccessful technique than conventional radiograph [23].According to these results; orthopanoramic radiographmost common graphy using for gap healing control isnot reliable in critical situations.

Table 5 Statistical values ofnew blood vessels in distractiongaps

Mean Variance Standard deviation Minimum Maximum Range

Group A-L 12.400 5.647 2.37627 10.20 15.70 5.50

Group A-K 8.2750 8.716 2.95226 5.00 12.00 7.00

Group B-L 8.25 4.083 2.02073 6.50 11.00 4.50

Group B-K 8.75 10.750 3.27872 4.50 12.50 8.00

Lasers Med Sci (2014) 29:213–220 219

In our study performed on rabbit mandibles, LLLT’slong- and short-term effects on DO have been assessed withconventional radiography, microtomography, histologic andhistomorphometric analysis and LLLT was proved to bemore effective short-term bone healing when compared tothe long-term healing scores. Obtained results indicate thatLLLT can be safely utilised as a supportive treatment modelto enhance bone healing in DO and prevent possible longterm. When the results of this experimental study performedon a rabbit model is considered to be reflected on clinicalDO applications, it can be concluded that consolidationperiod of this treatment method—and also the whole dura-tion—can be shortened and positively affected whensupported with LLLT.

The animal number used in the research is limited due todistractor application difficulties on rabbit mandible andethical limitations. It is hard to work such a model on rabbitmandible. So using more durable tough research animalscan facilitate the distraction researches. It was proved againthat LLLT accelerates the healing of distraction gaps withthis research. But the most effective laser type, applicationdose and time should be established with another animalstudies and these studies should be supported with clinicalapplications and researches.

Acknowledgements This research was supported by HacettepeUniversity Scientific Research Unit Research Grant.

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