Three-dimensional analysis of pulp chambers in maxillary second deciduous molars

Success Rate and Related Factors of Vitapex Pulpectomy in Primary Teeth: A Retrospective Study

OBJECTIVES

 Our aims were to evaluate the Vitapex pulpectomy (PE) success rate, Vitapex resorption rate, and their associated factors in primary teeth.

MATERIAL AND METHODS

 This retrospective study evaluated the clinical records of Vitapex PE-treated patients at the Pediatric Dental Clinic, Faculty of Dentistry, Mahidol University, from 2013 to 2019. The patient's and pulpectomized tooth's characteristics, procedure, materials used, and type of operator were recorded. A dentist evaluated and compared the periapical lesion, root status, obturation quality, and Vitapex resorption on preoperative, immediate, and follow-up digital radiographs. PE failure was defined as radiographic lesion progression.

STATISTICAL ANALYSIS

 The Kaplan-Meier method was used to estimate the Vitapex PE success rate and Vitapex resorption rate. Multivariate Cox regression was used to determine the related factors.

RESULTS

 In total, 647 Vitapex PE teeth from 448 patients (19-121-month-old) were analyzed. The follow-up periods ranged from 6 to 60 months. The success rate was 88.9 and 68.1% at the 12- and 24-month follow-up, respectively, and remained stable at 53.8% at the 36 to 60-month follow-ups. The factors related to Vitapex PE failure were age and a preoperative pathologic lesion. More than 50% of the pulpectomized teeth presented Vitapex resorption faster than physiologic root resorption at the 12-month follow-up. The patients' age at treatment and the obturation quality were significantly related to the Vitapex resorption rate.

CONCLUSIONS

 The success rate of Vitapex PE decreased time dependently and was related to the patient's age at treatment and a preoperative lesion. The Vitapex resorption was faster than root resorption and was associated with the patient's age at treatment and the root filling extravasation.

Microcomputed tomography void analysis after cement cleanup methods

STATEMENT OF PROBLEM

Cement at the restorative margin after implementation of the manufacturer's recommended procedure for cement cleanup has not been extensively evaluated.

PURPOSE

The purpose of this in vitro study was to use microcomputed tomography (μCT) to evaluate the number, volume, and width of voids left at the margin when dental cement is cleaned during the cementation process as per 2 manufacturer-prescribed methods for cement cleanup by evaluating a self-adhesive resin cement and a resin-modified glass ionomer cement.

MATERIAL AND METHODS

Twenty molar Ivorine Typodont prepared teeth were scanned, and lithium disilicate crowns were milled and cemented to the prepared teeth as per the manufacturer-recommended cementation process. Two methods of cement cleanup were performed: the excess cement was tack-polymerized with a polymerization light, or a delay of 3 minutes was used for the excess cement to reach partial polymerization, and the excess cement was removed with a sharp sickle scaler. These 2 methods of cement cleanup were performed with 2 cements: a resin-modified glass ionomer cement and a self-adhesive resin. Each specimen was then scanned with a μCT machine. The buccal margin of each specimen, from mesiobuccal line angle to distobuccal line angle, was examined, and the number, volume, and width of any voids remaining at the margin open to the environment were measured. For statistical analysis, the specimens were first grouped by method of cement cleanup and then grouped by cement type. The Wilcoxon ranked sum test was implemented because of the lack of a normal distribution and the heterogeneity of the data (α=.05).

RESULTS

No statistically significant difference was found in the median number of voids, median volume of voids, or median width per void between the 2 cleanup methods, irrespective of cement type (P>.05). Significant differences were found in the median number of voids, median volume of voids, and median width per void when comparing cement types, irrespective of cement cleanup methods (P<.05).

CONCLUSIONS

The choice of cement may be more important than the method of cement cleanup when considering voids left at the margin. Microcomputed tomography is an excellent nondestructive tool for volumetric measurements of voids at the margin.

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.

A retrospective study on the long-term outcomes of pulpectomy and influencing factors in primary teeth

Background/purpose

Materials and methods

Results

Conclusion

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.

Root Resorption of Maxillary Posterior Teeth after Rapid Maxillary Expansion: A Comprehensive Review of the Current Evidence from in-vitro and in-vivo Studies

Background:

The application of heavy forces to the dentition, as those produced during a Rapid Maxillary Expansion (RME), has been associated in the literature with the development of root resorption of maxillary posterior teeth.

Objective:

The aim of the present manuscript was to report the available data from in-vitro and in-vivo studies that can elucidate the biological processes of resorption and repair of radicular cementum after RME.

Methods:

Studies evaluating the occurrence of root resorption after RME by means of histological and radiographic methodology were included. We detailed the changes of the radicular anatomy after RME and provided a synthesis of the most valuable scientific evidence showing the biological processes behind the potential modifications of radicular anatomy. Results. Loss of cementum material and reduction of radicular volumes were seen after rapid maxillary expansion. A small radicular volumetric recovery of anchored teeth occurred after the retention period; this reparative phenomenon was caused by cementum deposition without the reattachment of periodontal fibers, supporting the detrimental effects associated with RR.

Conclusion:

Retention period and the timing of radiographic examination could influence the extension of radicular resorption detected after RME since root resorption and cementum repair may occur at the same time at this stage.

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

Purpose: To determine the three-dimensional (3D) tooth morphology of all primary molars and to identify and consolidate positional factors that could potentially have an effect on tooth preparation. Study design: Thirty-one non-carious primary molars were scanned using micro-CT and reconstructed using 3D analysis software. Each pulp horn to its respective cusp tip distance (PHCD) was measured as well as the distances from the pulp chamber to the mesial, distal, lingual and buccal surfaces. One-way ANOVA and post-hoc t-tests were used for data analysis. Results: The mesio-buccal and disto-buccal PHCD was significantly shorter than the mesio-lingual and disto-lingual PHCDs in maxillary second primary molars (P < 0.05). Mesial, distal and lingual walls were thinner than the buccal walls of mandibular molars while in maxillary molars; the mesial and distal walls were thinner than the palatal and buccal walls (P < 0.05). Conclusions: First primary molars have thinner tooth structure surrounding the pulp than second primary molars in the same arch with the exception of the buccal walls of all molars and lingual walls of maxillary molars. The mesial and distal walls are thinner than the buccal walls of all molars and lingual walls in maxillary molars.

In-vitro analysis of maxillary first molars morphology using three dimensional Micro-CT imaging: considerations for restorative dentistry

PURPOSE

The aim of this study was to determine the differences between the positional relationship of the crown contour and the pulp chamber of left and right maxillary first molars, as well as their morphological characteristics by using micro-CT system with reconstruction from a volumetric rendering software.

MATERIALS AND METHODS

In total, 21 extracted maxillary first molars, including 11 left and 10 right teeth, were used. The positional relationship between the crown contour, pulp chamber and morphology of the teeth were investigated three-dimensionally by means of micro-CT imaging.

RESULTS

Closest distance of mesio-buccal pulp horn to enamel surface in mm was calculated as 2.5±0.20 mm for right and 2.29±0.17 mm for left teeth. This difference was statistically significant (p=0.017). The means of closest distance of disto-buccal pulp horn to enamel surface were also significantly different between left and right teeth (p=0.001). The mean pulp volumes of right side and left side teeth were, respectively, 32.94±3.19 mm³ and 33.71±2.82 mm³ but this difference was not statistically significant.

CONCLUSION

These results suggest that right and left maxillary first molars should be treated differently during preparation of cavities. Further studies must be done with larger samples as well as for other molar teeth in different populations to reveal the morphology of the molar for further considerations in restorative dentistry.

Volume measurement of crowns in mandibular primary central incisors by micro-computed tomography

OBJECTIVE

To determine sex differences in the tissue proportions of crowns of mandibular primary central incisors in Chinese children and to quantify the volume of crown components in three dimensions using micro-computed tomography (micro-CT).

MATERIALS AND METHODS

The specimens used in this study were 41 mandibular first deciduous incisor teeth with intact crowns (21 males and 20 females) obtained from patients between 5-6 years of age. Each specimen was scanned using micro-CT at a resolution of 0.05 mm and 3D-rendered images were created. The volume of each component of the crown was measured and examined for differences in different sex and ages.

RESULTS

The pulp chamber volume decreased with age and the volume ratio of the pulp chamber to the whole crown was significantly smaller in 6-year-olds than in 5-year-olds (p < 0.05).

CONCLUSIONS

Males had significantly larger tooth crown volumes and dentin volumes than females did (p < 0.001), while the volume of enamel showed no sexual dimorphism.

Prospective in (Primate) dental analysis through tooth 3D topographical quantification

The occlusal morphology of the teeth is mostly determined by the enamel-dentine junction morphology; the enamel-dentine junction plays the role of a primer and conditions the formation of the occlusal enamel reliefs. However, the accretion of the enamel cap yields thickness variations that alter the morphology and the topography of the enamel–dentine junction (i.e., the differential deposition of enamel by the ameloblasts create an external surface that does not necessarily perfectly parallel the enamel–dentine junction). This self-reliant influence of the enamel on tooth morphology is poorly understood and still under-investigated. Studies considering the relationship between enamel and dentine morphologies are rare, and none of them tackled this relationship in a quantitative way. Major limitations arose from: (1) the difficulties to characterize the tooth morphology in its comprehensive tridimensional aspect and (2) practical issues in relating enamel and enamel–dentine junction quantitative traits. We present new aspects of form representation based exclusively on 3D analytical tools and procedures. Our method is applied to a set of 21 unworn upper second molars belonging to eight extant anthropoid genera. Using geometrical analysis of polygonal meshes representatives of the tooth form, we propose a 3D dataset that constitutes a detailed characterization of the enamel and of the enamel–dentine junction morphologies. Also, for the first time, to our knowledge, we intend to establish a quantitative method for comparing enamel and enamel–dentine junction surfaces descriptors (elevation, inclination, orientation, etc.). New indices that allow characterizing the occlusal morphology are proposed and discussed. In this note, we present technical aspects of our method with the example of anthropoid molars. First results show notable individual variations and taxonomic heterogeneities for the selected topographic parameters and for the pattern and strength of association between enamel–dentine junction and enamel, the enamel cap altering in different ways the “transcription” of the enamel–dentine junction morphology.

Evaluation of root resorption following rapid maxillary expansion using cone-beam computed tomography

OBJECTIVE

To evaluate the root resorption after rapid maxillary expansion (RME) via cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

Records of 25 patients who had undergone RME with tooth-borne banded expander were obtained from the archive of the orthodontic department. CBCT data were reconstructed with surface and volume rendering, and the volumetric images were manipulated to display the root surfaces from various orientations. On these three-dimensional images, permanent first molars and first and second premolars were segmented, and their roots were isolated. Volumes of roots were calculated. The difference between pre-expansion and postexpansion root volumes was statistically evaluated with a paired-samples t-test. Also, the percentage of root volume loss was calculated for each root and statistically compared with each other with one-way analysis of variance at the P < .05 level.

RESULTS

The difference between the pre-expansion and postexpansion root volumes was statistically significant for all roots investigated. Maximum volume decrease was observed for the mesiobuccal root of first molar teeth (18.60 mm(3)). It was determined that the distobuccal root of first molar teeth was less affected from the expansion procedure (9.47 mm(3)). No statistically significant difference was found for the percentage of root volume loss.

CONCLUSION

Following RME treatment, significant root volume loss was observed for all investigated posterior teeth. However, the percentage of volume loss was not statistically different among roots.

Quantitative measurements obtained by micro-computed tomography and confocal laser scanning microscopy

OBJECTIVES

To compare measurements obtained by micro-CT with those obtained by confocal laser scanning microscope in simulative internal resorption cavities.

METHODS

An extracted human maxillary central incisor tooth was divided into two in the coronal plane. Four artificial internal resorption cavities were prepared with standardized burs on each section, and diameters and volumes were measured using a laser scanning electron confocal microscope and a desktop cone beam micro-CT-40. Differences between means of quantitative measurements for both methods were tested using the paired t-test; the correlation between quantitative measurements was tested by regression analysis.

RESULTS

Mean diameter and volume differences between the two methods were 0.061 mm and 0.004 mm(3), respectively. Average diameter and volume calculations obtained by micro-CT were significantly lower (P < 0.001 for diameter and P < 0.01 for volume). A significantly strong relationship was found in the average diameters (R(2) = 92.9%) and calculated volumes (R(2) = 91%), (P < 0.001).

CONCLUSIONS

Although a strong correlation between both methods was found, micro-CT significantly underestimated the diameters and volumes.

Dental developmental pattern of the Neanderthal child from Roc de Marsal: a high-resolution 3D analysis

The assessment of the degree of similarity or difference between Neanderthals and modern humans in their patterns of dental development remains a controversial matter. Here we report results from the microtomographic-based (SR-microCT) high-resolution structural investigation of the maxilla and mandible of the Neanderthal child from Roc de Marsal, Dordogne, France (likely from OIS 5a). Following their virtual extraction and 3D rendering, we assessed the maturational stage of each of the 41 dental elements (20 deciduous and 21 permanent) forming its mixed dentition. By using a Bayesian approach, we calculated the probability that its deciduous and permanent mandibular sequences are found within the extant human variation as illustrated by a tomographic CT-based sub-sample of 32 children (deciduous dentition) and a panoramic radiographic- and CT-based whole sample of 343 living children (permanent dentition). Results show that neither the deciduous nor the permanent mandibular sequences displayed by Roc de Marsal are precisely found within our modern comparative files. In both sequences, the most influential factor is represented by a slight discrepancy in the Neanderthal child between the stage of mineralization of the first molar, which is proportionally advanced, and the maturational level reached by its incisors, which are proportionally delayed. Following a quantitative volumetric analysis of the deciduous teeth, we suggest that this characteristic may be related to differences between Neanderthals and modern humans in absolute dental size and relative size proportions between front and cheek teeth, as well as to structural differences in dental tissue proportions.