Pulp Chamber Analysis of Primary Molars Using Micro-Computed Tomography: Preliminary Findings

Three-Dimensional Analysis of the Pulp Chamber and Coronal Tooth of Primary Molars: An In Vitro Study

The anatomical variability of primary molars promotes research to improve clinical restorative activity, forensic identification, and industrial development. The objective was to study the morphology of the pulp chamber and its three-dimensional relationship with the external morphology of the tooth. A total of 151 deciduous molars were collected and subjected to three-dimensional imaging analysis in order to determine dental crown (CV) and pulp chamber (PV) volumes, their ratio (VR), pulp chamber roof (PCR) and pulp chamber floor (PCF) area, the furcation length (FD), and morphological peculiarities. The data were compared using the Kruskal–Wallis test in SPSS 26 software. The statistical analysis determined statistically significant differences between the four groups of molars for all variables. Great anatomical variability was observed, especially in the maxillary first molar, the volumes were higher in the maxillary second molar and the highest risk of furcal perforation was seen in the mandibular first molar. Additionally, mandibular second molars with six pulp horns, and some different density images compatible with accessory canals and pulp stones were found. Based on the findings of this investigation, we confirm the great anatomical variability that exists between the maxillary and mandibular molars.

Efficacy of Root Canal Instrumentation and Fracture Strength Assessment in Primary Molars after Preparing Two Different Shapes of Access Cavity: An Ex Vivo Histological Study

Aim and objective

To evaluate the efficacy of root canal instrumentation and fracture strength assessment in primary molars after preparing different shapes of access cavity design.

Materials and methods

Sixty extracted primary mandibular molars with at least 2/3rd roots were randomly, equally divided into two groups based on shapes of the access cavities; Group I: Traditional access cavity (TAC), Group II: Conservative access cavity (CAC). Each group was further subdivided into two subgroups with 15 samples each. After, root canal debridement, samples in subgroup 1 were sectioned for histological evaluation of root canal instrumentation efficacy, while subgroup 2 were assessed for fracture strength using a Universal Testing Machine. The data were analyzed statistically using Mann–Whitney and post hoc Tukey tests, with a p value <0.05.

Results

Traditional access cavity showed statistically significant root canal debridement efficacy (p < 0.05) compared with CAC. Statistically significant differences were obtained between fracture strength values among the two groups (p < 0.05), with considerably higher fracture strength in the CAC group than TAC.

Conclusion

Traditional access cavity design resulted in complete root canal debridement but caused weakening of tooth structure due to low fracture strength, necessitating the use of full coverage restoration postendodontic therapy.

How to cite this article

Singhal Y, Srivastava N, Rana V, et al. Efficacy of Root Canal Instrumentation and Fracture Strength Assessment in Primary Molars after Preparing Two Different Shapes of Access Cavity: An Ex Vivo Histological Study. Int J Clin Pediatr Dent 2021;14(4):518–524.

Comparison of dynamic mechanical properties of dentin between deciduous and permanent teeth

Purpose: Even though differences between deciduous and permanent dentin have been widely studied, their dynamic mechanical behavior has never been compared. The objective of the present study was to quantify the differences between deciduous and permanent dentin under cyclic mechanical loading, which is similar to masticatory stress.Materials and Methods: Deciduous and permanent teeth, respectively from children (9 ~ 12 years old) and young people (18 ~ 25 years old), were wet-sectioned perpendicular to the longitudinal axis and the central specimens of coronal dentin were evaluated by nanoscopic dynamic mechanical analysis (nanoDMA).Results: The average storage, loss, and complex moduli, as well as the hardness of deciduous dentin were significantly (p < 0.05) lower than those of permanent dentin. Moreover, the tan δ value of permanent dentin was significantly (p < 0.05) lower than that of deciduous dentin across the loading frequency range, indicating that viscoelastic behavior and loss of elastic energy were significantly reduced in the stiffer permanent dentin. All the nanoDMA responses showed a significant influence of the dynamic loading frequency (p < 0.05): Both deciduous and permanent dentin showed reduced viscoelasticty with increased loading frequencies.Conclusions: Compared with deciduous dentin, permanent dentin exhibits higher stiffness with reduced energy loss during deformation, and therefore superior mechanical characteristics for the mastication process.