IN-VITRO STUDY OF INTERNAL ROOT MORPHOLOGY OF MANDIBULAR FIRST AND SECOND PREMOLARS IN SOUTH INDIAN POPULATION USING CLEARING TECHNIQUE.
BRIEF RESUME OF THE INTENDED WORK : 6.1 NEED FOR THE STUDY :
The main objective of endodontic therapy is the thorough debridement of entire pulp canal space. Failure to perform this may leave behind irritants that can cause persistent periapical inflammation and failure of root canal treatment. In order to avoid this, the clinician needs to have a through knowledge of root canal morphology of the given tooth.1
The root canal system of mandibular premolars has been claimed and known to be particularly difficult to clean and shape. Ingle stated that the variation in canal anatomy might account for increase in endodontic failure of these teeth.2 Slowey also reported that mandibular premolars are the most difficult teeth to treat endodontically due to variation in root canal anatomy.3 The Dental Anatomy and Endodontic text books have shown to vary considerably in their description of canals of these teeth.4 Apart from its known complexity and unpredictability, Martin Trope et al showed that mandibular premolars had also differences in complexity among races.5 Subsequent researches have shown that differences exist between different racial groups such as Blacks, Chinese and Caucasians.5, 6 This study has been taken up in order to examine the prevalence of any such variation among the people of South India. Moreover, the result of this study will enable the clinicians in correlating the knowledge with clinical and radiographic findings.
6.2 REVIEW OF LITERATURE :
According to the study done by Baisden et al on 106 extracted mandibular first premolars using perpendicular sectioning method, 76% of premolars had Type I canal configuration and 24% contained Type IV configuration according to Weine’s classification. The shapes of these canals were predominantly round and oval.1
An in-vitro study was done by Vertucci FJ on 400 first and 400 second mandibular premolars. The teeth were decalcified, made transparent and injected with dye to determine the number, type and ramifications of the main canal. The results showed that mandibular first premolars having one apex were 74.0%, having two canals at the apex were 25.5% and having three canals at the apex were 0.5% of the teeth. In mandibular second premolar having one canal at the apex were 97.5% and having two canals at the apex were 2.5%.4
The study conducted by Martin Trope et al in 1986 demonstrated the differences in prevalence of more than one root canal in different Race Groups. The standard method of radiographic appraisal was used for the study. It was observed that 4 out of 10 Black patients had at least one lower premolar with two or more canals. Black patients had significantly higher number of premolars with more than one canal when compared to Whites (39% in Blacks versus 15.8% in Whites).5
According to the study done by Lu TY et al on 82 extracted mandibular first premolars in Chinese population, 6% had circumferential canal (apical delta), which was characterized by a single canal splitting into 3or 4 canals. They had used cross-sectioning method for study.6
Sikri VK and Sikri P had done an in-vitro study on 112 mandibular first premolar and 96 second premolar using radiographs from two directions and cross-sectioning at three sites. The results showed that 29.5% mandibular first premolars and 13.5% mandibular second premolars exhibited two root canals. Also approximately 10% mandibular first premolars showed C-shaped canals.7
6.3 AIMS AND OBJECTIVES OF THE STUDY: The objective of this study is to investigate the internal anatomy of root canals of extracted human mandibular premolars of South Indian Population. The result of this study will enable the clinicians in correlating the knowledge with clinical and radiographic findings and achieve greater success in treating these teeth.
MATERIALS AND METHODS : 7.1 SOURCE OF DATA :
300 extracted human mandibular premolars (150 mandibular first premolar and 150 mandibular second premolars) will be collected from dental clinics situated in South India.
7.2. METHODS OF COLLECTION OF DATA: The freshly extracted teeth will be stored as per the Centers for Disease Control and Prevention (US) infection control protocols global, until further processing.
Matured permanent first and second mandibular premolars extracted due to periodontal conditions, non-restorable caries and trauma will be selected for the study.1
Teeth with root resorption, fracture and teeth with incompletely formed apex will be excluded from the study.1
STUDY METHOD : After collection of sample is completed, the extracted teeth will be fixed in 10% neutral buffered formalin at room temperature. Thereafter teeth will be thoroughly washed under tap water.
An ultra sonic scaler will be used for the removal of gross tissue and calculus. Standard access cavities will be prepared and the teeth will be immersed in 3% NaOCl for 5-10 days to dissolve the pulp tissue. The teeth will be rinsed under running tap water and dried over night. Canal orifices will be located by using No.10 K files.8 India ink will be injected into the root canal system using an endodontic irrigating syringe assisted by apical application of vacuum suction. The teeth will be dried and subjected to decalcification procedure.9 Teeth will be immersed in 10% nitric acid for 10-15 days and the acid solution will be changed everyday.8, 9 Decalcification will be confirmed by probing method.
The teeth will then be subsequently rinsed under running tap water for four hours, later dried and dehydrated using ethanol in three increasing concentrations70%, 95% and 100% for 24 hours each. The teeth will be made transparent by submersion in methyl salicylate for 48 hours. 8,9
Upon the completion of clearing, the root canal configuration will be examined under microscope. Root canal configuration will be classified according to the collection of data.
STASTICAL ANALYSIS :
Estimation of proportion of anatomical variations.
95% confidence interval.
Stastical method will be according to the collected data.
7.3 Does the study require any investigations or interventions to be conducted on the patients or other humans or animals? If so, please describe briefly.
7.4. Has ethical clearance been obtained from your institution in caseof 7.3?
LIST OF REFERENCES : 1) Baisden MK, Kulid JC, Weller RN. Root canal configuration of the mandibular first premolar. J Endodon1992Oct;18(10):505-8.
3) Slowey RR. Root canal anatomy: road map to successful endodontics. Dent Clin North Am1979;23:567-70.
4) Vertucci FJ. Root canal morphology of mandibular premolars. J Am Dent Assoc 1978Jul;97:47-50.
5) Trope M, Elfenbein L, Tronstad L Mandibular Premolars with more than one root canal in different race groups. J Endodon1986Aug;12:343-45.
6) Lu TY, Yang SF, Pai SF. Complicated root canal morphology of mandibular first premolar in a Chinese population using cross-section method. J Endodon 2006 Oct;32(10):932-36.
7) Sikri VK, Sikri P. Mandibular premolars: aberrations in pulp space morphology. Indian J of Dent Res 1994 Jan-Mar;5(1):9-14.
8) Alavi AM , Opasanon A, Ng YL, Gulabivala K. Root and canal morphology of Thai maxillary molars. Int Endod J 2002;35;478-485.
9) Khraisat A, Smadi L. Canal configuration in the mesio-buccal root of maxillary first molar teeth of Jordanian population. Aust Endod J 2007;33:13-17.