Year : 2005 | Volume
: 23 | Issue : 3 | Page : 134--137
Root canal configuration of deciduous mandibular first molars - An in vitro study
Deepak Gupta, N Grewal
Department of Pedodontia and Preventive Dentistry. Punjab Government Dental College and Hospital, Amritsar, Punjab, India
Dept of Pedodontics, MM College of Dental Sciences and Research, Mullana, Ambala, Haryana
Root canal morphology of deciduous mandibular first molar was studied using roentgenographic and decalcification and clearing methods. Two groups of 15 teeth were formed. In the roentgenographic group, roots of the teeth were separated from the crown at the level of CEJ. Cut roots of the teeth were radiographed from both mesiodistal and buccolingual directions using separate IOPA films. In the decalcification and clearing group, teeth were decalcified and made transparent. Dye was injected later. The roots of the teeth were examined under 10 times for number, curvature, types and additional features of root canals. Deciduous mandibular first molar showed variability in root canal morphology. Four to five root canals were recorded. Majority of the teeth had 1-1 type of root canal anatomy, but 1-2 type anatomy was also reported. Straight, curved and S-shaped canal curvatures were recorded. Horizontal anastomosis, lateral canals and buccolingually broad root canals were also recorded.
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Gupta D, Grewal N. Root canal configuration of deciduous mandibular first molars - An in vitro study.J Indian Soc Pedod Prev Dent 2005;23:134-137
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Gupta D, Grewal N. Root canal configuration of deciduous mandibular first molars - An in vitro study. J Indian Soc Pedod Prev Dent [serial online] 2005 [cited 2020 Feb 23 ];23:134-137
Available from: http://www.jisppd.com/text.asp?2005/23/3/134/16886
The morphology of root canals in deciduous teeth usually leads to complications in root canal therapy. Endodontic procedures for the treatment of primary teeth are indicated if the canals are accessible and there is an evidence of essentially normal supporting bone. In deciduous teeth, intimate anatomical relation of the pulp to the periodontal tissues via accessory canals results in concomitant pulpal periodontal breakdown. IOPA radiograph shows the poor image of canals because root canals have three dimensions and it is impossible to see the buccolingual aspect of the canals as a result of superimposition of other tissues such as dentin, cementum, and cancellous and cortical bone of the alveolus.
An attempt was made to study the root canal morphology in relation to the tooth as a whole so that all the ramifications of the root canals along with accessory canals could be revealed thereby reducing the problems of endodontic therapy arising due to anatomical variations in root canals of teeth, which are clinically undetectable.
Materials and Methods
Thirty extracted deciduous mandibular first molars were collected from OPD of the Department Of Pedodontics and, Preventive Dentistry of Punjab Govt. Dental College and Hospital, Amritsar, which fulfilled the following criterias:
1. teeth with no evidence of root resorption,
2. teeth with or without caries,
3. teeth with intact root without any evidence of fracture.
The teeth were cleaned with soap and washed in running water. Hand scalers were used to remove calculus or soft tissues if present on root surfaces. The teeth were washed and stored in individual glass containers containing 10% formalin solution and bearing specimen codes. The study was conducted by two methods and the teeth were divided accordingly into two groups of 15 teeth each.
Group A -roentgenographic method (long cone technique) and Group B - decalcification and clearing method The materials used for decalcification and clearing method were as under [Figure 1]:
1. Sodium hypochlorite (5%) (NICE),
2. Nitric acid (69.72 % assay) (RANBAXY),
3. Ethyl alcohol (absolute) (RANBAXY),
4. Methyl salicylate (CDH laboratory reagent) (Central Drug House Pvt. Ltd., Mumbai),
5. Methylene blue alkaline (NICE).
Group A - Roentgenographic method
To avoid the superimposition of the root canals, roots were separated horizontally from the crown at the level of CEJ with a diamond disc 3/4th inch in diameter. The two roots were then separated by a vertical cut, if necessary. The cut roots of the specimens were radiographed from both mesio-distal and bucco-lingual directions. Separate IOPA films were used for taking radiographs in mesio-distal and bucco-lingual directions with long cone technique. The specimen's roots were fixed on IOPA X-ray films with soft wax such that the buccal surfaces of mesial and distal roots faced the cone of the X-ray machine. The cut roots were again stored in glass containers containing 10% formalin. The radiographs were examined under 10x magnification using magnifying glass in an X-ray viewer. Number and curvature of the root canals were carefully studied and findings recorded for evaluation.
Group B - Decalcification and clearing method
Teeth were decalcified and made transparent by using the technique followed by Robertson et al. After making the teeth transparent, methylene blue dye was injected from the coronal end of the canal. Suction, if needed, was applied at the apical end of the root canal to facilitate uniform flow of the dye. After injecting the dye, roots of the teeth were examined under 10x magnification. Number and curvature of the root canals were carefully studied and findings were recorded.
The observations made during the course of study are shown in [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6].
Roentgenographic method [Table 1], [Table 2], [Table 3], [Table 4]
In the specimens, selected for Roentgenographic study, findings are in concurrence with Hibbard and Ireland who stated that first primary molars might have a combination of 2-4 canals. Lesser number of specimens with multiple root canals were found in buccolingual view because of superimposition of root canals in this view.
Pineda et al. stated that intraoral radiographs show a very poor image of canals because the root canals have three dimensions. It is impossible to see the buccolingual aspect, generally only the cervical and middle third are clearly visible. Mesiodistal plane is reduced because of the superimposition of other tissues such as dentin, cementum and cancellous and cortical bone of the alveolar process. Regarding the different types of root canal curvatures [Figure 2] in the mesial root, two types of canal curvatures, i.e. straight and curved [Figure 3] were recorded. In the distal root, three types of canal curvatures, i.e. straight, curved and S-shaped [Figure 4] were recorded. These findings are not in concurrence with Hibbard and Ireland, who reported more frequent and greater variations in the mesial root canal than the distal root canal. Horizontal anastomosis [Figure 5] was observed in 6.67% of the specimens of the mesial root only when viewed form mesiodistal direction. No incidence of meshwork of transverse communications was found in distal root. Barker et al. as well as other authors had also reported the incidence of transverse communications between the root canals of deciduous mandibular first molars. No mention of the frequency of this meshwork in different canals was made. The observations of this study showed greater incidence in mesial root canals only.
The occurrence of lateral canals [Figure 6] in both mesial and distal roots was comparable with 6.67% of the specimens showing the incidence. These findings are in concurrence with Hibbard et al. who stated that lateral branches, connecting fibrils and apical ramifications might be encountered in deciduous mandibular molars.
Buccolingually broad root canals were observed in 33.33% of the specimens in distal root with no incidence in the mesial root. Barker et al. stated that broad root canals were considered to be a common finding in single and wide root canals of deciduous mandibular first molar specimens, but with maturity, dentin partitioning resulted in a meshwork of transverse communications eventually leading to complete or partially separated canals.
Decalcification and clearing method [Table 5] and [Table 6] The results exibited that 100% of the specimens had two canals in mesial root. In distal root 53.33% had two canals and 46.67% showed only one root canal. These results are in concurrence with our findings of roentgenographic method where also 100% of the specimens had two canals in the mesial root. In the distal root, similar results comparable to roentgenographic method were obtained. Regarding type of root canals in mesial root, 100% of the specimens had 1-1 type of anatomy, in the distobucal root canal, 1-1 type of anatomy was found in 93.33% of the specimens, 6.67% of the specimens had 1-2 type of root canal anatomy. In the distolingual root canal, 100% of the specimens had 1-1 type of root canals.
The type of canal curvatures, in mesiobuccal root canal, 100% of the specimens had straight canals. Mesiolingual root canal had 93.33% straight canal curvature, and 6.67% curved curvature. In the distal root, 100% of the specimens had straight canal curvature. Buccolingually broad root canals were observed in 13.33% of the specimens in distal root. When the compiled results of both the methods were analysed, it was seen that root canal morphology of deciduous mandibular first molars showed a maximum of five root canals in a specimens. But on an average, the majority of the specimens had four root canals.
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