Microsoft Word - Rosa Proof May 6.docx Vol 2, No 1 (2014) ISSN 2167-8677 (online) DOI 10.5195/d3000.2014.19 http://dentistry3000.pitt.edu This work is licensed under a Creative CommonsAttribution 3.0 United States License. This site is published by the University Library System, University of Pittsburgh as part of its D-Scribe Digital Publishing Program and is cosponsored by the University of Pittsburgh Press. Manual and rotary instrumentation techniques for root canal prepa- ration in primary molars Francinne M. Rosa1, Adriana Modesto2, Italo M. Faraco-Junior3 1Private Practice, Porto Alegre, RS, Brazil 2University of Pittsburgh, School of Dental Medicine, Pittsburgh, PA, USA 3Private Practice, Porto Alegre, RS, Brazil Abstract Introduction: Although rotary instrumentation has been widely studied in permanent den- tition, it is a rather new field of study concerning primary teeth. Purpose: We aimed to evaluate apical displacement and time needed for instrumentation of root canals of pri- mary molars by manual and rotary techniques. Materials and Methods: Root canals of 144 extracted first and second primary maxillary molars were randomly divided into 2 groups: I- manual instrumentation (K-files); II- rotary instrumentation (K3 Rotary System®). The canals were radiographed with pathfinding files in place, prepared by both techniques, and in- strumentation time was recorded. After preparation, root canals were radiographed again with pathfinding files in place. To analyze the degree of apical displacement, digital images were superimposed using the Adobe Photoshop® software. Results: Mean apical displace- ment (0.70 mm) in the manual instrumentation group was not statistically different from that in the rotary instrumentation group (0.79 mm). However, mean time for root canal preparation was significantly shorter using the rotary system (128.0 s) than using the man- ual system (174.0 s) (p<0.05). Conclusions: The use of rotary instrumentation in pediatric dentistry is feasible, offering time-saving advantages in root canal preparation. Citation: Rosa FM, Modesto A, and Faraco-Junior IM. (2014) Manual and rotary instrumentation techniques for root canal preparation in primary molars. Dentistry 3000. 1:a001 doi:10.5195/d3000.2014.19 Received: January 14, 2014 Accepted: April 24, 2014 Published: May 27, 2014 Copyright: ©2013 Rosa et al. This is an open access article licensed under a Creative Commons Attribution Work 3.0 United States License. Email: faraco@globo.com Introduction The use of rotary instrumentation in pediatric dentistry is a rather new field of study, al- though it has been widely studied in perma- nent dentition. Studies have compared rotary with manual instrumentation performance for root canal preparation in permanent teeth. The results have shown no significant differences in the cleaning capacity between techniques, but rotary instrumentation prepared canals more rapidly and uniformly [1,2]. In addition, the rotary instruments can reach the entire length of the root canal, causing little or no dis- placement, particularly in the apical region [3- 5]. Rotary instrumentation characteristics be- come significantly relevant when dealing with endodontic preparation of primary teeth, since appointment length is a crucial factor for pediatric patient compliance, and maintaining the original path of the root canal is essential to ensure the integrity of the germ of the permanent successor [6,7]. Considering the reduced number of studies on this topic in pediatric dentistry, this study aimed to elucidate the apical displacement produced in root canals and the time needed for root canal preparation in primary teeth by the rotary instrumentation system in compari- son with the manual instrumentation tech- nique. Materials and Methods Sixty-four primary max- illary molars extracted with no previous endo- dontic treatment, inter- nal and/or external root resorption, and over two-thirds of resorbed root were selected for the study. After sample size calculation (power of 90%, confidence level of 95%), the sample was composed of 144 roots (Table 1): 24 me- siobuccal, 24 distobuccal, and 24 palatal roots of the first primary maxillary molars; and 24 mesiobuccal, 24 distobuccal, and 24 palatal roots of the second maxillary molars. These roots were cleaned with periodontal curettes, decontaminated with 1% sodium hypochlorite and sterilized in 10% formalin. All teeth were previously embedded in clear acrylic-resin blocks. For this purpose, a thin layer of wax was placed on dental apex to seal the inlet channels, and the teeth were sunken until the Table 1: Distribution of the primary molars. Tooth Mesiobuccal root Distobuccal root Palatal root First primary maxillary molar 24 24 24 Second primary maxil- lary molar 24 24 24 Total number of each root 48 48 48 Total number of roots=144 http://dentistry3000.pitt.edu Manual and rotary instrumentation techniques for root canal preparation in primary molars Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.19 http://dentistry3000.pitt.edu 2 Figure 1: Tooth embedded in clear acrylic-resin block. Figure 3: Manual instrumentation with K-files. level of acrylic-resin covered the roots (Figure 1). After crown access, the teeth were irrigated with 1% sodium hypochlorite and the working length was determined by passive insertion of a K-file with a rubber stop. When the file tip was at the level of the dental apex, the rubber stop was leveled with the respective cusp tip and the length of each root canal was re- corded. The working length was determined by subtracting 2 (two) mm from the total length of the root canals. The root canals were then placed on a radio- graphic platform and radiographed in proxi- mal (mesial/distal) and frontal (palatal/buccal) directions, with pathfinding files in place, us- ing a direct digital imaging sensor (Cygnus MPD®,CygnusInc., Redwood City, CA, USA), in order to record pathfinding file position in the apical region of root canals. Radiographs were obtained with Gnatus X-ray equipment (Gna- tus Equipamentos Médico-Odontológicos Ltda, Ribeirão Preto, São Paulo, Brazil), 70X, 70 kVp and 7 mA, at 30 cm focal distance, 90° core radius, and 0.08 seconds exposure time. Biomechanical preparation of all root canals was performed by a single operator, with resin blocks fixed on a device that secured blocks in the same position (Figure 2). Instru- mentation time for each root canal was re- corded, and each instrument, in both groups, was used in 10 samples. The roots were randomly divided into two groups: - Group I (n=72): manual instrumentation. (1) coronal opening; (2) irrigation with 1% sodium hypochlorite (performed throughout the preparation); (3) location of root canals (4) root canal instrumentation using K-files: utili- zation of initial instrument (better fit in the root canal) and three sequential instruments (Figure 3). - Group II (n=72): rotary instrumentation. (1) coronal opening; (2) irrigation with 1% sodium hypochlorite (performed throughout the preparation); (3) location of root canals (4) root canal instrumentation using with K3 Ro- tary System® (Sybron Endo, Orange, CA, USA) in the sequences # 25/0.8, # 30/0.6, # 25/0.4, and # 25/0.2 (crown-apex direction), set in motion by an Endo Standard Pro Torque® mo- tor (Dentsply, Rio de Janeiro, RJ, Brazil) at 250 rpm speed (Figure 4). After biomechanical preparation, root canals were placed again on the radiographic plat- form and radiographed in proximal and fron- tal directions, with pathfinding files in place, being careful to maintain the same standard conditions (position and other exposure fac- tors). Post-biomechanical preparation radiographs were digitally superimposed over their pre- preparation counterparts using the Adobe Photoshop® software (Figure 5). A straight line was drawn to connect the tips of the instru- ments inside the canals, thus generating two displacement measurements: one for frontal and one for proximal view. Real apical dis- placement was measured (in millimeters) by a pre-calibrated examiner, blinded to technique assignment, by calculating the third side of a triangle constructed by the measurement of the displacement obtained from frontal and proximal view. Reproducibility of the results was verified every five images analyzed. Statistical analysis was performed with the Statistical Pack- age for the Social Sciences (SPSS) soft- ware, version 14.0, and significance level of 5%. Data regarding apical displacement were compared using the Kruskal-Wallis test and the Mann- Whitney test. Differ- ences in instrumenta- tion time were statis- tically analyzed with ANOVA, post hoc Tukey s test, and the Student s t test. Results In the manual group, the lowest apical dis- placement was observed in the distobuccal root of the first primary maxillary molar (0.15 mm) and the greatest apical displacement was found in the mesiobuccal roots of the first and second primary maxillary molars (1.64 mm). In regard to the time, palatal root of the second maxillary molar showed the lowest value (121 s), and the highest value was observed in the mesiobuccal root of the second primary maxil- lary molar (416 s). In the rotary group, the lowest value for apical displacement was observed in the palatal root of the first primary maxillary molar (0.10 mm) and the greatest value in the distobuccal root of the first primary maxillary molar (3.09 mm). The shortest instrumentation time in the ro- tary technique was observed in the palatal root of the second primary maxillary molar (78 Table 2: Analysis of apical displacement (in millimeters) comparing the tech- niques used (rotary vs. manual instrumentation). Tooth Root Rotary Manual p* 1PMM Mesiobuccal 0.27 0.43 0.184 1PMM Distobuccal 0.85 0.63 0.175 1PMM Palatal 0.24 0.14 0.839 2PMM Mesiobuccal 0.28 0.56 0.599 2PMM Distobuccal 0.49 0.35 0.166 2PMM Palatal 0.38 0.18 0.049 1PMM=first primary maxillary molar; 2PMM=secondary primary maxillary molar. *Statistically significant p values (p<0.05). Mann-Whitney nonparametric test. Figure 2: Acrylic-resin block positioned for instrumentation. http://dentistry3000.pitt.edu Manual and rotary instrumentation techniques for root canal preparation in primary molars Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.19 http://dentistry3000.pitt.edu 3 Figure 4: Rotary instrumentation with K3 Rotary System ®. Figure 5: (A) Initial radiograph; (B) Final radiograph; (C) Overlay of digital images. s) and the longest time in the mesiobuccal root of the first primary maxillary molar (296s). The evaluation of apical displacement for each root type, after post hoc analysis for means, comparing manual and rotary techniques, showed no statistically significant differences (Table 2). With regard to the time needed for instru- mentation using manual and rotary tech- niques, within the same root type group, sta- tistically significant differences were observed in all root types, except for the mesiobuccal root of the first primary maxillary molar. The shortest time for instrumentation was achieved with the rotary instrumentation technique (Table 3). An overall data analysis, regardless of root type, showed no significant differences when comparing the degree of apical displacement within manual and rotary techniques. How- ever, considering instrumentation time, the rotary technique needed a significantly shorter time than the manual technique. Discussion This study sample was composed of extracted primary teeth, aiming to reproduce prepara- tion conditions as similar as possible to in vivo conditions, since standardized root canals exclude some variables found in natural teeth [8]. Furthermore, the reduced number of studies using rotary instrumen- tation in primary teeth [6,7,9-19] justifies the com- parison of our findings with some studies in permanent teeth [1,2,20-25]. With regard to apical displacement, there were no statisti- cally significant differences between tech- niques, when root types and groups were analyzed altogether, although displacements occurred in all root types and in several ways. These results are consistent with those found by Nazari Moghaddam et al. [9], Azar, Mokhtare [10], and Igbal et al. [20], but disagree with the results found by Loizides et al. [21], which may be explained by the fact that simulated root canals were used, as well as a rotary system different than the one employed in the present study. Furthermore, the highest values for apical displacement produced in mesiobuccal roots, which usually show a higher degree of curvature [8], occurred using the manual instrumentation technique. In distobuccal and palatal roots, however, the highest values were obtained with rotary instrumentation. Elmsallati et al. [22] showed that K3 Rotary System® produces minimum wear of root ca- nal walls, which is an interesting aspect in the endodontic preparation of primary teeth. Moreover, Crespo et al. [11] and Musale, Mu- jawar [12] stated that rotary files prepared more conical canals in primary teeth than manual instruments. When analyzing canal curvature, it is well known that the degree of curvature does not affect the performance of K3 Rotary System® [23,24] validating the good performance of this system in mesiobuccal roots observed in this study. In the present study, two instrument fractures were observed, both with K3 Rotary System®, although this is considered one of the safest systems [23,25]. Nagaratna et al. [13], work- ing on primary teeth, already pointed out as a disadvantage of the rotary system its higher fracture rate. Two root perforations occurred in the present study, both in the rotary instrumentation group. Only one [14] of the previous studies performed in primary teeth [6,7,9-13,15-18] reported such event, which might be attrib- uted to the operator s level of skill in using the system. Moreover, Kummer et al. [14] stated that in some specimens, root perforations were observed in areas coinciding with largest root resorption. In regard to instrumentation time, when the groups were analyzed altogether, there was a significant difference between techniques, and the shortest preparation time was achieved with the rotary technique. The pre- sent results corroborate those findings in the existing literature, on instrumentation per- formed in primary teeth, which describe quick preparation as the main advantage of using rotary instruments in pediatric dentistry [6,7,9-19]. Our data showed significant differences in time needed for instrumentation between roots within the same instrumentation group (manual or rotary). The palatal root of the maxillary second molar needed the shortest time for instrumentation, in both techniques, because it is straight and wide, whereas the longest instrumentation time was observed in the preparation of mesial roots, because they are curved and slender [8]. We also observed that the highest values in time needed for instrumentation were ob- Table 3: Analysis of time (in seconds) comparing the techniques used (rotary vs. manual instrumentation). Tooth Root Rotary Manual p* 1PMM Mesiobuccal 163.3 181.8 0.410 1PMM Distobuccal 149.3 244.6 0.007* 1PMM Palatal 131.7 151.7 0.042* 2PMM Mesiobuccal 123.7 256.0 0.001* 2PMM Distobuccal 133.0 206.2 <0.001* 2PMM Palatal 111.1 145.9 0.001* 1PMM=first primary maxillary molar; 2PMM=secondary primary maxillary molar. *Statistically significant p values (p<0.05). Student t test. http://dentistry3000.pitt.edu Manual and rotary instrumentation techniques for root canal preparation in primary molars Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.19 http://dentistry3000.pitt.edu 4 tained with the manual technique, in all root types, except for the mesial root of the first primary maxillary molar. Therefore, we can state that root anatomy affects instrumenta- tion time, since deviant root anatomy leads to longer instrumentation time for both the manual and rotary technique. The results obtained in the present study are quite satisfactory concerning the reduction of instrumentation time by the rotary technique, a fact already reported in previous studies in primary teeth. However, there was no statisti- cal significant difference between techniques concerning apical displacement when root types and groups were analyzed altogether, although displacements occurred in all root types and in several ways. Pinheiro et al. [19] stated that endodontic treatment in children may be challenging and time consuming, especially during root canal preparation, which is one of the most impor- tant stages of endodontic therapy. Consider- ing that the rotary instruments provide similar root canal cleaning compared to manual in- struments with a shorter instrumentation time, their utilization is well indicated in Pedi- atric Dentistry. In conclusion, rotary instrumentation is feasi- ble and an important tool to be used in the endodontic preparation of primary teeth since it requires a shorter clinical time from the pediatric patient. Acknowledgements None of the authors have a direct financial relation with any commercial identities men- tioned in this paper, nor have any other con- flict of interests to declare. We thank Dr. Car- los Alberto Feldens for helping us in the statis- tical analysis. References 1. Comparing apical preparations of root canals shaped by nickel- titanium rotary instruments and nickel-titanium hand instruments. Deplazes P, Peters O, Barbakow F.J Endod. 2001 Mar;27(3):196-202. PMID: 11487151 2. Effectiveness of manual and rotary instrumentation techniques for cleaning flattened root canals. Bar- bizam JV, Fariniuk LF, Marchesan MA, Pecora JD, Sousa-Neto MD. J Endod. 2002 May;28(5):365-6. PMID: 12026920 3. Efficiency of rotarynickel-titaniumK3 instruments compared with stainless steel hand K-Flexofile. Part 2. Cleaning effectiveness and shap- ing ability in severely curved root canals of extracted teeth. Schäfer E, Schlingemann R. Int Endod J. 2003 Mar;36(3):208-17. PMID: 12657147 4. A comparison of Profile, Hero642, and K3 instrumentation systems in teeth using digital imaging analysis. González-Rodrguez MP, Ferrer- Luque CM. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2004 Jan;97(1):112-5. PMID: 14716266 5. In vitro evaluation of the thermal al- terations on the root surface during preparation with different Ni-Ti ro- tary instruments. Capelli A, Guerisoli DM, Barbin EL, Spanó JC, Pécora JD. Braz Dent J. 2004;15(2):115-8. Epub 2005 Mar 11. PMID: 15776193 6. Use of nickel-titanium rotary files for root canal preparation in pri- mary teeth. Barr ES, Kleier DJ, Barr NV. Pediatr Dent. 1999 Nov- Dec;21(7):453-4. PMID: 10633522 7. Use of nickel-titanium rotary files for root canal preparation in pri- mary teeth. Barr ES, Kleier DJ, Barr NV. Pediatr Dent. 2000 Jan- Feb;22(1):77-8. PMID: 10730297 8. A three-dimensional study of canal- curvatures in the mesial roots of mandibular molars. Cunningham CJ, Senia ES. J Endod. 1992 Jun;18(6):294-300. PMID: 1402588 9. Root canal cleaning efficacy of ro- tary and handfiles instrumentation in primary molars. Nazari Moghad- dam K, Mehran M, Farajian Zadeh H. Iran Endod J. 2009 Spring;4(2):53-7. Epub 2009 Apr 17. PMID: 23940486 10. Rotary Mtwo system versus manual K-file instruments: efficacy in pre- paring primary and permanent mo- lar root canals. Azar MR, Mokhtare M. Indian J Dent Res. 2011 Mar- Apr;22(2):363. doi: 10.4103/0970- 9290.84283. PMID: 21891918 11. Comparison between rotary and manual instrumentation in primary teeth. Crespo S, Cortes O, Garcia C, Perez L. J Clin Pediatr Dent. 2008 Summer;32(4):295-8. PMID: 18767460 12. Evaluation of the efficacy of rotary vs. hand files in root canal prepara- tion of primary teeth in vitro using CBCT. Musale PK, Mujawar SA. Eur Arch Paediatr Dent. 2014 Apr;15(2):113-20. doi: 10.1007/s40368-013-0072-1. Epub 2013 Jul 27. PMID: 23893606 13. In vitro comparison of NiTi rotary in- struments and stainless steel hand instruments in root canal prepara- tions of primary and permanent mo- lar. Nagaratna PJ, Shashikiran ND, Subbareddy VV. J Indian Soc Pedod Prev Dent. 2006 Dec;24(4):186-91. PMID: 17183182 14. Ex vivo study of manual and rotary instrumentation techniques in hu- man primary teeth. Kummer TR, Calvo MC, Cordeiro MM, de Sousa Vieira R, de Carvalho Rocha MJ. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2008 Apr;105(4):e84- 92. doi:10.1016/j.tripleo.2007.12.008. PMID: 18329573 15. Comparison of rotary and manual instrumentation techniques on cleaning capacity and instrumenta- tion time in deciduous molars. Silva LA, Leonardo MR, Nelson-Filho P, Tanomaru JM. J Dent Child (Chic). 2004 Jan-Apr;71(1):45-7. PMID: 15272656 16. Comparison of conventional, rotary, and ultrasonic preparation, different final irrigation regimens, and 2 seal- ers in primary molar root canal therapy. Canoglu H, Tekcicek MU, Cehreli ZC. Pediatr Dent. 2006 Nov- Dec;28(6):518-23. PMID: 17249433 17. Comparison between rotary and manual techniques on duration of instrumentation and obturation times in primary teeth. Ochoa- Romero T, Mendez-Gonzalez V, Flores-Reyes H, Pozos-Guillen AJ. J Clin Pediatr Dent. 2011 Sum- mer;35(4):359-63. PMID: 22046692 18. K-file vs ProFiles in cleaning capacity and instrumentation time in primary molar root canals: an in vitro study. Madan N, Rathnam A, Shigli AL, In- dushekar KR. J Indian Soc Pedod Prev Dent. 2011 Jan-Mar;29(1):2-6. doi: 10.4103/0970-4388.79907. PMID: 21521910 19. Evaluation of cleaning capacity and instrumentation time of manual, hybrid and rotary instrumentation techniques in primary molars. Pinheiro SL, Araujo G, Bincelli I, Cunha R, Bueno C. Int Endod J. 2012 Apr;45(4):379-85. doi: 10.1111/ j.1365 2591.2011.01987.x. Epub 2011 Dec 22. PMID: 22188162 20. Comparison of apical transportation in four Ni-Ti rotary instrumentation http://dentistry3000.pitt.edu Manual and rotary instrumentation techniques for root canal preparation in primary molars Vol 2, No 1 (2014) DOI 10.5195/d3000.2014.19 http://dentistry3000.pitt.edu 5 techniques. Iqbal MK, Maggiore F, Suh B, Edwards KR, Kang J, Kim S. J Endod. 2003 Sep;29(9):587-91. PMID: 14503833 21. Root canal transportation with a Ni- Ti rotary file system and stainless steel hand files in simulated root canals. Loizides A, Eliopoulos D, Kon- takiotis E. Quintessence Int. 2006 May;37(5):369-74. PMID: 16683684 22. Debris retention and wear in three different nickel-titanium rotary in- struments. Elmsallati EA, Wadachi R, Ebrahim AK, Suda H. Aust Endod J. 2006 Dec;32(3):107-11. PMID: 17201751 23. Comparative study of six rotary nickel-titanium systems and hand instrumentation for root canal preparation. Guelzow A, Stamm O, Martus P, Kielbassa AM. Int Endod J. 2005 Oct;38(10):743-52. PMID: 16164689 24. A comparative study of root canal preparation with NiTi-TEE and K3 ro- tary Ni-Ti instruments. Jodway B, Hülsmann M. Int Endod J. 2006 Jan;39(1):71-80. PMID: 16409331 25. Deformation and fracture of RaCe and K3 endodontic instruments ac- cording to the number of uses. Troian CH, Só MV, Figueiredo JA, Oliveira EP. Int Endod J. 2006 Aug;39(8):616-25. PMID: 16872456 http://dentistry3000.pitt.edu