DTME0910

Trends & Applications DENTALTRIBUNE Middle East & Africa Edition4 _Since the early days of den- tistry, dentists have explored the morphology of the internal root anatomy. From the pre-X- ray period to the techno logy- driven present, the study and exami nation of the root-canal system has become an obses- sion for endo dontists. Several methodssuchasradiographic1 and histolo - gical examina- tions,2–3 cross-and longitudi- nal sectioning, 4 and root- clearing techniques, to name a few, were widely used in the past. Today, different comput- erised tomography studies5 and observations under dental operating microscopes6 are performed to light up the dark confines of the dental pulp. _The tooth-clearing tech- nique Over the last 100 years, the tooth-clearing technique was utilised in human dental pulp morphology studies, as it pro- vides a 3-D view of the pulp cav- ity in relation to the exterior of the teeth and allows a thorough examination of the pulp cham- bers and root canals.7–9 It was also utilised in the study of apical leakage.10 Today, the clearing techniqueremainsusefulonlyas a teaching and research tool, with little or no clinical applica- bility.11 In 1913, Hermann Prinz suc- cessfully cleared teeth using the protocolproposedbySpaltholzin 1906.12 Okumura performed in- depth studies of the pulp anatomy and classified the canals according to their distri- bution and prevalence.13 In or- der to simplify the canal system visually, he injected ink into the pulp cavity.13 Samples can also be stained with Haematoxylin and Eosin, which are largely used to colour histological preparations. Compared with other procedures such as radi- ographicandhistologicalexami- nations, the tooth-clearing tech- nique has the following advan- tages: _ retains the original form of the root; _ enables the observation of minute details of the root- canal morphology; _ is inexpensive; _ samples can be conserved for a long time; and _ is easy to perform. The clearing process consists of three basic steps: demineralisation, dehydra- tion and clearing of the root structure.14–15 Sample preparation _Storeextractedteethin10%for- mal saline until use.11 _Scale calculus and any remains of periodontal tissue. _Decoronate samples and nego- tiate canals with a #10 file (this will enhance acid penetra- tion). _Store samples in 4.2% NaOCl solution (the organic tissue re- moval can be enhanced by placing the solution with the samples in the Ultrasonic Cleaner for 20 minutes). _Wash under running water and dry. _Indian ink can be drawn through the root-canal system by applying negative pressure to the apical end.Deminerali- sation _Store samples in 5% nitric acid (HNO3) for three days. _Change solution every eight hours. _Manualormechanicalagitation promotes even demineralisa- tion of the root. _Wash samples under running waterforfourhours16toclean. Dehydration _Dehydrate samples by using as- cending grades of alcohol: 60 % ethanol for eight hours, 80% ethanol for four hours, and 96.6% ethanol for two hours. _Dry samples with paper towels. Clearing _The sample should be placed in xylene for two hours to harden prior to placing the samples in methyl salicylate to render themtransparent.16(Thisstep isessentialifsamplesaregoing tobeusedforpractisinginstru- mentation or obturation tech- niques.) _Store samples in methyl salicy- late in order to preserve their transparency. Please note: Always use proper protection when han- dling these dangerous solutions. Disposal of the used solutions should be done according to country regulations. _Educational tool Successful root-canal treat- ment depends on adequate cleaning, shaping and filling of the root-canal system. However, in order to achieve this goal, it is imperative that the operator has a detailed know - ledge of the root-canal morphology of each individual tooth that is treated. Demineralised and cleared teeth may become a very valuable aid in the teaching of endodontic techniques. Hasselgren and Tronstad17 used cleared teeth to teach and practise instrumenta- tion and obturation procedures in a preclinical course at Lund University, Sweden. At the end of the course, the students were asked to give their opinions re- garding the use of the transpar- ent teeth in the learning process. The reaction was very favourable and encouraged the head of the department to extend the use of cleared teeth in follow- ing courses.17 Dipping the samples in xy- lene for two hours, as suggested by Robertson in 1980, prior to placingtheminmethylsalicylate will return dentine hardness to values slightly lower than those found in normal dentine.16 This yields new possibilities for den- tists eager to learn, who wish to practise new techniques, proce- dures and protocols, from rotary instrumen - tation with NiTi files to thermoplastic obturation with warm gutta-percha. Dentists are able to see what is actually hap- pening with much greater detail, which is a significant improve- ment to working with a simu- lated canal in plastic blocks. Ad- ditionally, the tactile feeling ex- perienced is very similar to the real clinical situation. In summary, this simple and inexpensive technique will en- abledentiststovisualisetheroot- canal morphology in detail while allowing them to practise almost every endodontic procedure de- sired._ Editorial note: A list of refer- ences is available from the pub- lisher. DT Transparent teeth: A powerful educational tool Author_ Dr Sergio Rosler, Argentina Fig. 1 Fig. 2 F Fig. 4 Fig. 5 Fig. 3 Dr Sergio Rosler gradu- ated from the University of Buenos Aires, Argentina, in 1996, and had become a spe- cialist in Endodontics by 2005. HehasbeenaspecialistinOral Implantology since 2009 and works in private practice in Buenos Aires. He can be contacted at : sarosler@hotmail.com.ar About the author