Treatment time for non-surgical endodontic therapy with or without a magnifying loupe

Transcription

1 Wong et al. BMC Oral Health (2015) 15:40 DOI /s RESEARCH ARTICLE Treatment tme for non-surgcal endodontc therapy wth or wthout a magnfyng loupe Open Access Amy Wa-yee Wong 1, Xaofe Zhu 2*, Shnan Zhang 1, Samantha Ka-yan L 1, Chengfe Zhang 1* and Chun-Hung Chu 1 Abstract Background: Use of magnfyng loupe may ncrease the effcency of dental care. Ths clncal tral compared the tme n performng non-surgcal endodontc therapy wth or wthout the use of a magnfyng loupe. Methods: Patents who requred prmary endodontc treatment n clncal tral centres at the Unversty of Hong Kong (HKU) n Hong Kong and Pekng Unversty (PKU) n Bejng were nvted to partcpate n ths study. Two HKU dentsts and 2 PKU dentsts, formng 2 pars of dentsts wth smlar years of clncal experence, performed endodontc treatments accordng to the same procedures and used the same materals, ether n sngle or multple vsts. They had no pror experence wth the use of a magnfyng loupe. One dentst from each par was traned to use a magnfyng loupe (x2.5). The treatment tme was recorded. Results: Eghty-four PKU patents wth a mean age of 42.8 years and 98 HKU patents wth a mean age of 46.0 years were recruted n ths study. Nnety-sx teeth were treated wth a magnfyng loupe and 86 teeth were treated wthout a magnfyng loupe. The results showed that treatment tme was not assocated wth age, gender, tooth vtalty, or the presence of apcal radolucency or snus tract. The results of ANCOVA revealed the treatment tme was assocated wth the clnc (HKU or PKU), root canal system (sngle or multple), presence of preoperatve pan, treatment vst (sngle or multple), the use of a magnfyng loupe, and the experence of the operator. Concluson: In ths study, the use of a magnfyng loupe could sgnfcantly reduce the endodontc treatment tme. Tral regstraton: Clncal Trals ChCTR-IOR regstered 15 February Keywords: Endodontc, Tme, Magnfyng loupe, Clncal tral, Root canal therapy Background The advancements n the development of dental equpment have enhanced clncans ablty and success n performng root canal treatments on ther patents. A magnfyng loupe s a pece of equpment that ncreases the effcency and qualty of dental care. Clncans use of a magnfyng loupe ncreases vsual acuty [1] and the accuracy of the endodontc procedure. The superor vsualsaton of the treatment feld attaned by usng a magnfyng loupe mproves dagnostc capablty [1,2] and endodontc outcomes [3]. The use of a loupe also mproves the dentst s workng posture and reduces the rsk of developng repettve-stress njures related to poor body poston [4]. * Correspondence: zhuxaofe767@foxmal.com; cfzhang@hku.hk Equal contrbutors 2 School and Hosptal of Stomatology Specal Servce Clnc, Pekng Unversty, Bejng, Chna 1 Faculty of Dentstry, The Unversty of Hong Kong, Hong Kong, Chna Workng whle usng a magnfyng loupe has become an ncreasngly accepted practce n dentstry. Not only has t become an accepted practce for many dental specaltes, but s consdered mandatory n the endodontc programs at some dental schools [5,6]. Wth the ad of a magnfyng loupe, the vsualsaton of the surgcal feld s enhanced; as a result, the dagnostc capablty s mproved. The magnfyng loupe often enables the dentst to confrm the presence of cracks, both n the natural crowns of teeth and n the roots of teeth restored wth post crowns [7]. The dentfcaton of dentnal cracks was reported to be hgher (45%) than the naked eye (39%) n the same study. A careful examnaton of the gngval margns under the loupe may dentfy external root resorpton. The margnal ft of restoratons and the presence of cares can also be checked. The use of a loupe also ncreases the effcency of operatve procedures, especally wth regard to endodontc 2015 Wong et al.; lcensee BoMed Central. Ths s an Open Access artcle dstrbuted under the terms of the Creatve Commons Attrbuton Lcense ( whch permts unrestrcted use, dstrbuton, and reproducton n any medum, provded the orgnal work s properly credted. The Creatve Commons Publc Doman Dedcaton waver ( apples to the data made avalable n ths artcle, unless otherwse stated.

2 Wong et al. BMC Oral Health (2015) 15:40 Page 2 of 6 and aesthetc dental treatment [1,5,8]. Most dentsts have reled prncpally on ther normal vsual acuty (20/ 20 vson). The pulp chamber and even the canals themselves can be sclerosed n teeth wth large cares. Even for a dentst who has a good knowledge of canal anatomy can fnd t dffcult to locate the root canals n a calcfed pulp chamber [1]. The use of a magnfyng loupe may help the clncan to dentfy the root canal entrance and probable extra canals [3]. Once the canal entrances have been dentfed, the subsequent cleanng and shapng procedures can be performed n a farly straghtforward manner. A randomsed clncal tral concluded that the use of a magnfyng loupe may ncrease the success rate of root-end endodontc treatment [9]. In addton, the use of a magnfyng loupe can enhance the accuracy of endodontc procedures [1]. Because of the complexty of the root canal system, canal preparaton cannot necessarly be consdered complete, even wth the help of modern rotary nstrumentaton and the accompanyng rrgaton regmes. The magnfyng loupe wll help the clncan to dentfy the presence of sthmuses, a C-shaped root canal, and even areas of the canal system that have remaned unprepared. The magnfyng loupe s also useful for checkng canal cleanlness pror to obturaton [1]. Hence, the use of a magnfyng loupe n endodontc treatment should mprove clncal and radographc outcomes. As Cochrane (2009) found, clncal tral s necessary to substantate ths asserton [10]. Despte the number of advantages of usng a magnfyng loupe n endodontc treatment, some dentsts do not use one durng endodontc treatment [1,2,4,8]. Some of them may beleve the use of a magnfyng loupe ncreases the amount of tme requred to perform endodontc procedures [4,8]. Therefore, ths study was conducted to compare the tme t took to perform endodontc treatment wth or wthout the use of a magnfyng loupe. The hypothess was there would be no dfference n the charsde tme used n endodontc therapy wth or wthout a magnfyng loupe. Methods Patent recrutment The study was approved by the Insttutonal Revew Board of the Unversty of Hong Kong/Hosptal Authorty Hong Kong West Cluster (HKU UW ) n Hong Kong and Pekng Unversty (PKU IRB ) n Bejng, Chna. Chnese patents who were generally healthy and requred prmary endodontc treatment va the HKU Health Servce Dental Clnc n Hong Kong and the PKU School and Hosptal of Stomatology Specal Servce Clnc n Bejng were nvted to partcpate n the study. They were allocated systematcally nto 2 groups by the receptonsts: endodontc treatment wth loupes and endodontc treatment wthout loupes. Teeth wth pulpotomes were not accepted, and at least half of the coronal structure had to reman. The protocol of the study was explaned to partcpants and consent was obtaned. Patents who had severe acute pulpts wth facal swellng or systemc nfecton, severe systemc dsease, ncreased stress on the temporomandbular jont musculature, or ncreased psychologcal stress were excluded from ths study (Fgure 1). Sample sze calculaton The outcome measure s the total charsde tme for endodontc treatment. The tme for endodontc treatment or root canal therapy (RCT) vares accordng to the number and shape of the canals. For sample sze calculaton, we estmated that the tme for RCT s, on average, 90.0 mnutes; a 13.5-mnute (15%) dfference between the test and control groups we regarded as clncally sgnfcant. The sgma (common standard devaton) was estmated to be 30 mnutes. Usng an 80% power and a 5% statstcal sgnfcance level, the number of samples requred for each group was 78 or 156 n total. Clncal procedure Two dentsts from HKU and 2 dentsts from PKU formed 2 pars of dentsts wth smlar years of clncal experence to carry out the endodontc treatments. One dentst from each clnc was traned to use the same type of Gallean magnfyng loupe at 2.5x (N-25R, Yee Mau Industral Co., Kwa Chung, Hong Kong). The tranng nvolved dscusson n a semnar and performng endodontc treatment wth a magnfyng loupe on patents. All 4 dentsts performed endodontc treatments on patents randomly assgned by the receptonst wth a personal computer. The charsde assstant recorded the total treatment tme for each vst to the nearest mnute by usng a stopwatch. The dentsts receved a tranng workshop pror to ths clncal tral to standardse the nstrumentaton and obturaton technque descrbed below. Local anaesthetc was gven and a rubber dam was used for solaton. The root canals were prepared by usng a crown-down technque, whch prepares the coronal part of the canal before the apcal porton wth rotary endodontc nckel ttanum fles (ProTaper N-T fles, Dentsply Asa, Hong Kong). A 5.25% sodum hypochlorte soluton was used for rrgaton. After the preparaton and f the tme was avalable, the canal could be obturated at the same vst. If the canals were unable to be completely dred or the scheduled appontment tme was used up, the completon of the procedure was scheduled for another appontment. Non-settng calcum hydroxde was used as canal medcaton and the access of the tooth was

3 Wong et al. BMC Oral Health (2015) 15:40 Page 3 of 6 Fgure 1 Flow dagram of the study. sealed wth a resn-modfed znc oxde and eugenol cement (IRM, Dentsply Asa, Hong Kong) between vsts. The prepared tooth was to be obturated n the subsequent vst. Data analyss The collected data was entered nto a personal computer and analysed wth the IBM SPSS Statstcs 21.0 program. The Kolmogorov-Smrnov normalty test was performed for normalty testng. Natural logarthmc transformaton was appled on the outcome varable (endodontc treatment tme) f the data dd not follow normal dstrbuton. Two-sample t-tests were used to assess the dfference n the transformed treatment tme wth the ndependent varables, whch were the patents gender, study ste, quadrant, tooth locaton, root of the endodontcally treated tooth, tooth vtalty, presence of apcal radolucency before treatment, snus tract, preoperatve pan, vst of the RCT, and the use of a magnfyng loupe. Regressons were used to assess the relatonshp of the transformed treatment tme wth the patent s age and the experence of the operator. Analyss of covarance (ANCOVA) was used to study the ndependent varables, ncludng the patents gender and age, study ste, quadrant, tooth locaton, root of the RCT tooth, tooth vtalty, presence of apcal radolucency before treatment, snus tract, preoperatve pan, vst of the RCT, the use of a magnfyng loupe, and the experence of the operator. All of the ndependent varables were entered nto the model. Backward stepwse procedures were performed untl only varables demonstratng a statstcally sgnfcant assocaton remaned n the fnal model. The level of statstcal sgnfcance was set at 5%. Results A total of 84 PKU patents, aged 42.8 ± 17.3, and 98 HKU patents, aged 46.0 ± 15.5, were recruted (Fgure 1). At PKU, 35 teeth wth one canal and 49 teeth wth multple canals were treated; at HKU, 38 teeth wth one canal and 60 teeth wth multple canals were treated. The endodontc treatment tme and varables studed are summarzed n Table 1. Also, the patents age was not related to the treatment tme (p = 0.813), but the experence of the operator was related to the treatment tme (p < 0.001) n the regressons (Estmate ± SE s ± 0.008, not shown n the table). Because the endodontc treatment tme dd not follow normal dstrbuton (Kolmogorov-Smrnov normalty test, p < 0.001), neutral logarthmc transformaton was appled and the transformed endodontc treatment tme passed the Kolmogorov-Smrnov normalty test (p = 0.200). The results of ANCOVA found that the treatment tme was assocated wth clnc locaton, root canal, preoperatve pan, treatment vst, the use of a loupe, and

4 Wong et al. BMC Oral Health (2015) 15:40 Page 4 of 6 Table 1 Endodontc treatment tme accordng to separated varables Group (No. of teeth) Treatment tme/mn (Mean ± SD) P-value # Gender Male (N = 66) 60.3 ± 30.3 Female (N = 116) 58.9 ± 34.1 Study ste <0.001 Hong Kong (N = 98) 76.2 ± 33.5 Bejng (N = 84) 39.9 ± 17.4 Quadrant Upper (N = 102) 60.8 ± 34.6 Lower (N = 80) 57.6 ± 30.3 Tooth locaton <0.001 Anteror (N = 42) 36.4 ± 16.7 Posteror (N = 140) 66.3 ± 33.2 Root canal <0.001 Multple (N = 109) 74.4 ± 31.9 Sngle (N = 73) 37.1 ± 17.8 Tooth vtalty Yes (N = 75) 62.1 ± 39.3 No (N = 107) 57.5 ± 27.1 Apcal radolucency Presence (N = 80) 58.5 ± 28.7 Absence (N = 102) 60.2 ± 35.6 Snus tract Presence (N = 16) 56.3 ± 24.0 Absence (N = 166) 59.7 ± 33.5 Preoperatve pan Presence (N = 75) 63.7 ± 30.4 Absence (N = 107) 56.4 ± 34.0 Vst Multple vsts (N = 91) 63.1 ± 37.5 Sngle vst (N = 91) 55.7 ± 26.8 Use of magnfyng loupe Yes (N = 96) 56.7 ± 23.5 No (N = 86) 62.5 ± 40.5 # P-value of two-sample t-test for log-transformed data. the experence of the operator (Table 2). The treatment tme n Hong Kong s clnc was longer than that n Bejng (p < 0.001). The treatment tme for multple root canals ncreased by an addtonal 85% for a sngle root canal (p < 0.001). The presence of preoperatve pan also ncreased the treatment tme by 9% (p = 0.028). Multple vsts ncreased the treatment tme by 32% more than a sngle vst (p < 0.001). The use of a magnfyng loupe (p < 0.001) and years of the operators experence (p < 0.001) helped to reduce the treatment tme by 20% and 24%, respectvely. Dscusson Accordng to the results of ths study, the null hypothess that there would be no dfference n the charsde tme used n endodontc therapy wth or wthout a magnfyng loupe s rejected. The belef of some dentsts that t takes longer to perform endodontc procedures wth a magnfyng loupe s not substantated. There s nsuffcent control for the potental confoundng effect by techncal and bologcal complexty of treatment. For example, f the treatment could not be completed wthn one vst due to bologcal reason, the total amount of treatment tme would nevtably be longer than those cases completed n a sngle vst. However, the dfference could not be attrbutable to the use of loupes but was due to bologcal reasons. The am of ths study was not to test the effect of tranng n usng magnfyng loupes. Otherwse, the study would have recruted many dentsts from the two clncs. It s noteworthy that the dentsts years of dental practce and ther experence n usng magnfyng loupes vared. In ths study, only two dentsts n each clnc wth no experence n usng magnfyng loupes and wth the same years of dental practce were recruted. The small number of dentsts recruted could mnmse the bas resultng from any unfamlarty on the part of the partcpatng dentsts wth the stpulated treatment protocol. Standardsaton of treatment protocol and tranng of the four partcpatng dentsts were ntroduced wth the am of reducng potental bas. The two dentsts who used a magnfyng loupe were newly ntroduced to ts use. Learnng the magnfyng loupe may take some tme, but the learnng curve s apparently Table 2 Log of endodontc treatment tme and varables n the fnal ANCOVA model Varables Estmate Exp (Estmate) Exp (95% CI) P-value Study ste Hong Kong Bejng a <0.001 Root canal multple sngle a <0.001 Preoperatve pan presence absence a Vst multple vsts sngle vst a <0.001 Use of magnfyng loupe Yes No a <0.001 Experence of the operator <0.001 a Reference Category, R 2 = 0.815, Adjusted R 2 =

5 Wong et al. BMC Oral Health (2015) 15:40 Page 5 of 6 short [1]. The two dentsts found the use of a magnfyng loupe ncreased the effcency of the endodontc treatment and enhanced ther accuracy n endodontc procedures. Another sgnfcant beneft of usng a magnfyng loupe n endodontc treatment s n the feld of ergonomcs. Endodontc treatment often requres the operator to mantan a certan posture for a consderable length of tme, and such a posture can take ts toll on the operator. Back, shoulder, and neck problems are common because of ncorrect posture [1]. The use of a magnfyng loupe enabled the operators to work on patents wth an ncreased workng dstance. Such a practce also allows an operator to hold hs or her back straghter than when workng wthout magnfcaton [1]. Ths study also demonstrated that the presence of preoperatve pan and multple vsts would ncrease the treatment tme. One of the reasons mght be that t takes longer to remove the nter-appontment medcament and to dry up the root canal before obturaton. Patents who had nflammaton mght requre more tme for local anaesthesa, whch mght even be neffectve n extreme cases. Another factor that sgnfcantly affected the treatment tme was the operator s experence. Experenced clncans requre shorter treatment tme than ther peers who are less experenced. Ths study was performed at two clncal tral centres and allows a comparson between them. The benefts of ths two-centre clncal tral are that they allow the study to nclude an adequate number of partcpants wthn 12 months. The dfferent geographc locatons also permt the study to nclude a wder range of patent groups whose tooth anatomy s dfferent. The results of ths study showed that the treatment tme was assocated wth the clncal tral centre, root canal system, presence of preoperatve pan, treatment vst, the use of a magnfyng loupe, and the experence of the operator. The dentsts at the PKU clncal centre were remunerated by the number of tems performed, whereas those n the HKU clncal centre were compensated wth a fxed salary. Ths compensaton format can explan the dfference n treatment tme between the two centres. Lo et al. reported that the remuneraton system would affect the clncan s performance [11]. Chu et al. also found that salary-based dentsts spent more tme communcatng wth patents than those who were pad by the tem (.e., who tend to perform faster than average dentsts) [12]. Durng data analyss, neutral logarthmc transformaton s a common method for manpulatng the outlyng data from a postvely skewed dstrbuton to one that s closer to the bulk of the data to allow the varable to be normally dstrbuted [13]. In ths study, usng a model n whch the outcome varable has been log-transformed and the predctors have not, t s natural to nterpret the exponental functon of the ANCOVA coeffcents. In terms of (smplfed) equatons, the model wth logtransformed outcome varable s log Y ¼ β þ X k β X for k ndependent varables and thus Y ¼ e β O þ X k β X 1 [14]. Therefore, a 1-unt ncrease n X (an ndependent varable) wll produce an expected ncrease n log Y (outcome varable) of β unts. In terms of (unlogged) Y tself, ths means the expected value of Y s multpled by e β. Therefore, whle all other varables n the model are held constant, the outcome varable changes by 100 tmes the exponental functon of the model parameter estmate as a percentage for a 1-unt ncrease n a contnuous ndependent varable. Smlarly, to nterpret the effect of a categorcal ndependent varable, the outcome varable changes by 100 tmes the exponental functon of the model parameter estmate as a percentage for a specfed category compared wth the reference category. In ths study, the use of magnfyng loupes would help to shorten the tme taken to perform non-surgcal endodontc treatment. As n other operatve procedures, the operators have an mproved vson feld when performng endodontc procedures. In addton, the mproved vson would enhance the clncans confdence n dagnoss before commencng the treatment. The fact that the procedures can be performed wth a more accurate vsual feld may further mprove the treatment outcome. Clncal procedures and dagnostc capablty may be better aded wth magnfcaton devces n comparson to unaded vson [1]. Dental armamentarum s contnuously changng to mprove the clncal outcomes n patent care. Human vson has lmtatons. Wth the help of magnfyng devces, clncans can vew more detals and, accordngly, the treatment outcome s enhanced. Therefore, clncans should ncorporate magnfyng devces (.e., magnfyng loupes) nto daly practce to obtan better magnfcaton [15]. Nevertheless, long-term studes to compare the outcome of endodontc treatment between usng operatve mcroscopes and magnfyng loupes are stll nadequate [10,16,17]. Mamoun reported that aded hgher-magnfcaton loupes (4 ) may work better than unaded entry-level (2.5 ) magnfyng devces [5]. Therefore, we may consder that workng effcency s related to the power magnfcaton. Surgcal mcroscopes have hgher magnfcaton than magnfyng loupes. A study showed that more accessory canals were detected by usng a mcroscope than wth a magnfyng loupe [18]. Another study also reported that sgnfcantly more canal orfces were found usng a surgcal mcroscope than by usng a magnfyng loupe [19]. However, a lterature revew found there was no sgnfcant dfference n the treatment results of endodontc mcrosurgery wth respect to the type of magnfcaton devce [20,21].

6 Wong et al. BMC Oral Health (2015) 15:40 Page 6 of 6 When general dentsts encounter dffculty n performng root canal treatment, they refer the case to a specalst. Thus, endondontc specalsts are more lkely than general dentsts to accept challengng cases, and ther need to use surgcal mcroscopes s hgher. The Amercan Assocaton of Endodontsts reported that most of the specalst n the Unted States ncorporate a surgcal mcroscope nto ther daly practce [22]. On the contrary, t s stll not wdely accepted by general dentsts, for example, n the Unted Kngdom [23]. Implementng hgher magnfcaton wll perforce ncrease the cost of runnng a clnc and also requre a great deal of tranng on ts utlsaton wthn daly practce. Therefore, general dentsts stll do not wdely use hgher magnfcaton, so contnung dental educaton s essental. A study n Scotland revealed that general dentsts used magnfcaton prmarly n conjuncton wth crown and brdgework, dagnoss, and radography to enhance the vsual feld [4]. In ths study, one of the partcpatng dentsts thought the use of magnfcaton n clncal practce was tme consumng. In addton, clncans must overcome a steep learnng curve to mprove ther operatve work [1]. Therefore, operators face a long journey n the acceptance of the use of magnfcaton n ther clncal practce [8]. It also takes tme to become accustomed to workng wth low or hgh magnfcaton because the depth of one s feld of vew s reduced. Furthermore, not all dentsts are ready to change ther approaches; some of them may consder other factors, such as cost-effectveness and the tranng tme that would be requred [1]. Concluson Endodontc treatment tme was sgnfcantly reduced by the use of a magnfyng loupe. Competng nterests The authors declare that they have no competng nterests. Authors contrbutons AWW was the prmary researcher n Hong Kong. XZ was the project dentst n charge n Bejng. SZ asssted the clncal tral. SKL performed the statstcal analyss of the study. CZ and CC planned the study and contrbuted equally to ts supervson. All authors read and approved the fnal manuscrpt. Authors nformaton Dr. A. W. Wong s a PhD student, Ms. S. K. L s a statstcan, Dr S Zhang s the project co-ordnator and Drs. C. H. Chu and C. Zhang are clncal assocate professors n the Faculty of Dentstry, The Unversty of Hong Kong. Dr X. Zhu s a clncal assocate professor n the School and Hosptal of Stomatology Specal Servce Clnc, Pekng Unversty. Receved: 27 September 2014 Accepted: 5 March 2015 References 1. Fredman M, Mora AF, Schmdt R. Mcroscope-asssted precson dentstry. Compend Contn Educ Dent. 1999;20: , , Blahuta R, Stanko P. The use of optcal magnfyng devces n perradcular mcrosurgery. Bratsl Lek Lsty. 2012;113: Eskandarnezhad M, Ghasem N. Nonsurgcal endodontc retreatment of maxllary second molar wth two palatal root canals: a case report. J Dent Res Dent Cln Dent Prospects. 2012;6: Forge AH, Pne CM, Longbottom C, Ptts NB. The use of magnfcaton n general dental practce n Scotland a survey report. J Dent. 1999;27: Mamoun JS. A ratonale for the use of hgh-powered magnfcaton or mcroscopes n general dentstry. Gen Dent. 2009;57: quz 27 18, Maggo MP, Vllegas H, Blatz MB. The effect of magnfcaton loupes on the performance of preclncal dental students. Quntessence Int. 2011;42: Slaton CC, Loushne RJ, Weller RN, Parker MH, Kmbrough WF, Pashley DH. Identfcaton of resected root-end dentnal cracks: a comparatve study of vsual magnfcaton. J Endod. 2003;29: Arens DE. Introducton to magnfcaton n endodontcs. J Esthet Restor Dent. 2003;15: Tascher S, Del Fabbro M, Testor T, Francett L, Wensten R. Endodontc surgery usng 2 dfferent magnfcaton devces: prelmnary results of a randomzed controlled study. J Oral Maxllofac Surg. 2006;64: Del Fabbro M, Tascher S, Lod G, Banf G, Wensten RL. Magnfcaton devces for endodontc therapy. Cochrane Database Syst Rev. 2009;3:CD do: / CD pub Lo EC, Yeung JC, Chu CH. Fee-payng systems and servce patterns n a Hong Kong dental clnc. Int Dent J. 2002;52: Chu CH, Yeung CY, Lo EC. Montorng patent satsfacton wth unversty dental servces under two fee-payng systems. Communty Dent Oral Epdemol. 2001;29: Bland M. An Introducton to Medcal Statstcs. 3rd ed. Oxford: Oxford Medcal Publcatons; Bulman JS, Osborn JF. Statstcs n dentstry. London: Brtsh Dental Assocaton; Garca A. Dental magnfcaton: a clear vew of the present and a close-up vew of the future. Compend Contn Educ Dent. 2005;26: Tascher S, Del Fabbro M, Wensten T, Rosen E, Tsess I. Magnfcaton n modern endodontc practce. Refuat Hapeh Vehashnaym. 2010;27: Tsess I, Rosen E, Tascher S, Telshevsky Strauss Y, Ceresol V, Del Fabbro M. Outcomes of surgcal endodontc treatment performed by a modern technque: an updated meta-analyss of the lterature. J Endod. 2013;39: Karapnar-Kazandag M, Basran BR, Fredman S. The operatng mcroscope enhances detecton and negotaton of accessory mesal canals n mandbular molars. J Endod. 2010;36: Yoshoka T, Kobayash C, Suda H. Detecton rate of root canal orfces wth a mcroscope. J Endod. 2002;28: Tascher S, Wensten T, Tsess I, Bortoln M, Del Fabbro M. Magnfyng loupes versus surgcal mcroscope n endodontc surgery: a four-year retrospectve study. Aust Endod J. 2013;39: Del Fabbro M, Tascher S. Endodontc therapy usng magnfcaton devces: a systematc revew. J Dent. 2010;38: Amercan Assocaton of Endodontcs (AAE) Poston Statement. Use of mcroscopes and other magnfcaton technques. J Endod. 2012;38: Burke FJ, Wlson NH, Chrstensen GJ, Cheung SW, Brunton PA. Contemporary dental practce n the UK: demographc data and practsng arrangements. Br Dent J. 2005;198(27): Acknowledgements The authors wsh to thank the partcpatng patents and the nvolved staff of HKU Health Servce Dental Clnc n Hong Kong and the PKU School and Hosptal of Stomatology Specal Servce Clnc n Bejng for ther support to the study. Ths study was supported The Unversty of Hong Kong (HKU) Small Project Fundng No and regstered n Chnese Clncal Tral Regstry n 2015 (Clncal Trals ChCTR-IOR ).