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Objectives: To evaluate the tooth lengths, crown to root ratios (CRRs), and alveolar bone support (ABS) around cleft-adjacent maxillary central incisors (U1s) in patients with unilateral cleft lip and alveolus (UCLA) and to investigate the relationships between CRR and ABS. Design: This is a retrospective study. Setting: Cleft Lip and Palate Care Center of Shanghai Ninth People’s Hospital, Shanghai, China. Patients: Fifty-eight Chinese patients with UCLA. Main Outcome Measure: Cone beam computed tomography data from 58 nonsyndromic patients with UCLA (36 males, 22 females; mean age = 12.65 ± 3.64 years) were evaluated. Crown length and root length, alveolar bone thickness (ABT), and the distances between the cementoenamel junction and alveolar bone crest on 4 surfaces of cleft-adjacent U1 were measured and compared with those of noncleft side in the same patients. Crown to root ratio and frequency of dehiscence were calculated and comparisons were also made between cleft and noncleft sides. Regression analysis was performed to explore the association between CRR and ABS. Results: The CRR of cleft-adjacent U1 and alveolar bone crest heights (ACHs) on the 4 surfaces were significantly greater than those of noncleft side ( P < .01). A 3 mm labial, all lingual, and apico-distal ABTs decreased on the cleft side ( P < .01). A positive correlation was found between lingual ACH and CRR ( R = 0.316, P < .05), between the 3 mm ( R = 0.417, P < .05) and 6 mm labial ( R = 0.448, P < .05) ABT and CRR. A negative correlation was found between the 3 mm and 6 mm labial ABTs and the root length. Conclusions: It can be suggested that the CRR is related to ACH and ABT. The lingual ACH, the 3 mm, and 6 mm labial ABTs tend to increase with the increasing CRR.

Aims and objectives To comparatively evaluate the clinical efficacy of stepwise caries excavation with indirect pulp capping (IPC) in managing the young permanent teeth in pediatric patients who have deep carious lesions. Materials and methods Eighty-eight teeth (first/second permanent molars) were included and randomly divided into two groups: group I (stepwise caries excavation) and group II (IPC). For group I, i.e., stepwise caries excavation, in the initial visit, bulk caries removal was done from walls of the cavity, however, soft and infected dentin was left untouched on the pulpal floor. The final excavation was performed after 2 months. The dentin parameters like the color, the consistency, and the humidity of dentin were noted at the first and second visits. A final follow-up to assess the primary outcome, i.e., sustained pulp vitality, was done after 1 year. Results When both the groups were compared with each other using the Chi-squared test, a highly significant difference was found (p < 0.05) between them. The success rate of stepwise caries excavation (97.3%) was found to be significantly greater than IPC (82.4%). After doing statistical analysis, a significant difference between stepwise excavation at baseline and at re-entry for parameters like the color, the consistency, and the humidity (p < 0.05), where dentin was observed to be darker in color, harder in consistency, and drier to touch at re-entry was found. Conclusion Stepwise caries excavation was considered a safer technique than IPC for preserving the vitality of young permanent teeth. Also, the clinical changes recorded during the re-entry in the case of stepwise caries excavation technique indicated the arrest of the carious process. Clinical significance Pulp preservation is of utmost importance especially in the case of young permanent teeth which have open apex to aid in apexogenesis. Failure to do so in maintaining the vitality of pulp before root completion may lead to the unfavorable crown to root ratio resulting in thin dentinal walls which are prone to fracture. How to cite this article Manhas S, Pandit IK, Gugnani N, et al. Comparative Evaluation of the Efficacy of Stepwise Caries Excavation vs Indirect Pulp Capping in Preserving the Vitality of Deep Carious Lesions in Permanent Teeth of Pediatric Patients: An In Vivo Study. Int J Clin Pediatr Dent 2020;13(S-1):S92–S97.

Aim: To assess the influence of the crown height, root length, crown-to-root ratio, and tooth type on the survival of teeth subjected to surgical endodontic retreatment and classified as periapically healed. Methodology: A single operator performed endodontic microsurgery interventions between 2008 and 2018 on teeth with refractory apical periodontitis. The present analysis selected the teeth classified as “complete periapical healing” according to the scale suggested by Molven. The postoperative periapical radiographs and those taken at the last recall visit were analysed by two independent calibrated examiners, who measured crown height and root length in a blind manner. The crown-to-root ratio was calculated as the ratio of the two variables. The level of inter- and intra-operator agreement was tested with Bland–Altman plots with 95% limits of agreement. An independent statistician conducted a survival analysis using Kaplan–Meier plots and a log-rank test (α = 0.05) to assess the significance of the differences among the subgroups defined by the following criteria: (a) crown height median; (b) root length median; (c) crown-to-root ratio 1; (d) crown-to-root ratio median; (e) single-rooted teeth vs. multi-rooted teeth. Results: At the end of the analysis, 42 patients were evaluated, each one contributing to the study with a single tooth. The mean follow-up period was 4.2 ± 2.4 years. Survival estimates were significantly improved for the teeth with roots longer than 8 mm, in comparison with that with shorter roots (p mediana; lunghezza radicolaremediana; rapporto corona-radice1; rapporto corona-radicemediana; denti monoradicolati vs. pluriradicolati. Risultati: Al termine dell’analisi il campione era costituito da 42 pazienti, seguiti per 4,2±2,4 anni, ciascuno dei quali ha contribuito allo studio con un dente. Le stime di sopravvivenza sono risultate significativamente migliori per i denti con radici più lunghe di 8 mm nel confronto con quelle di lunghezza inferiore (p

Objectives: To examine the relationship between tooth length and growth hormone receptor (GHR) gene variants in a healthy Japanese population. Materials and Methods: The subjects consisted of 193 Japanese adults (69 men, 124 women), aged 13 to 56 years. Genomic DNA was extracted from saliva and genotyped GHR rs6184 and rs6180 variants using the Taqman genotyping. Computed tomography (CT) images were acquired using a dental cone-beam CT scanner and reconstructed using open-source OsiriX medical image processing software. The maxillary (upper; U) and mandibular (lower, L) central incisors (1), lateral incisors (2), canines (3), first premolars (4), second premolars (5), first molars (6), and second premolars (7) were evaluated. Teeth were assessed for crown height (CH), root length (RL), overall tooth length (C+R), and crown to root ratio (C/R). The relationships between GHR variants and CH, RL, C+R, and C/R were statistically examined. Results: The GHR variant rs6184 was associated with the root lengths and tooth length for the upper and lower lateral incisors and upper canines (U2 RL; U3 RL, C+R; L2 RL [P < .05]). Conclusions: The results indicate that the GHR rs6184 variant is associated with tooth length and ratio dimensions in a Japanese cohort. Further studies utilizing a larger sample size are needed to confirm this finding.

Aim Assessing the application of three-dimensional clinical attachment loss (3D-CAL), 3D supporting bone loss (3D-SBL), supracrestal tissue attachment (STA), and crown-to-root ratio (CRR) in evaluating the 2017 periodontitis classification. Materials and methods We analysed ninety single-rooted human premolars with micro-computed tomography. The amount of 3D-SBL, linear radiographic bone loss (RBL), and CRR corresponding to various periodontitis stages as well as the statistical significance was investigated. Results From a 3D perspective, the premolars with a 21% of 3D-SBL at 2.0 mm coronal root length (RL) and 15% RBL corresponded to the periodontitis stage I. Premolars with a 44% of 3D-SBL at coronal 4.2-4.4 mm RL and 33% RBL accorded with the periodontitis stage II. Excluding the consideration of STA, CRR = 5:6 and 4:3 were associated with the levels at 15% and 33% RBL, respectively. Conclusions A greater percentage of 3D-CAL than that of 2D-CAL is significant at evaluated levels. It is feasible to correlate the 3D-SBL, 3D-CAL, and STA parameters to evaluate the stages of periodontitis severity. However, the current use of RBL and CAL as applied for staging in the 2017 classification might be inconsistent with the evaluated premolar roots length, when STA dimensions are considered.

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The relationship between the portion of the tooth coronal to the alveolar crest of bone compared with the portion embedded in it, has always been regarded as a vital aid in predicting the prognosis of teeth. However, controversy persists as to its impact on diagnosis and treatment planning. This article critically reviews the available literature on the crown-to-root ratio assessment and the shift in paradigm related to the criteria for evaluation of abutment use of periodontally compromised teeth. Also various treatment modalities present to improve an unfavourable crown-to- root ratio have been stated. A Medline search was completed for the time period from 1961 to 2005, along with a manual search to locate relevant peer reviewed articles and textbooks published in English. There was a scarcity of evidence-based research on the topic. Although the use of crown-to- root ratio along with other clinical indices may offer the best clinical predictors, no definite recommendations could be ascertained.

Pulp necrosis of immature permanent teeth represents a significant challenge for clinical management as root development ceases and open apices remain. The aetiology of pulp necrosis in immature permanent teeth can include caries, trauma or the presence of the dental anomalies, dens invaginatus and dens evaginatus. Endodontic treatment is complicated by the resultant thin dentinal root walls and the lack of apical closure. The long-term prognosis is compromised by increased risk of cervical root fracture and reduced crown to root ratio. Currently there is a paradigm shift in the management of such cases from traditional apexification procedures towards regenerative endodontic procedures. Regenerative endodontics can promote continued root development and apical closure, which does not occur with calcium hydroxide or mineral trioxide aggregate apexification. As supporting evidence grows and clear treatment guidelines are developed for regenerative endodontics, it is likely to become the gold standard for management of such teeth.

To compare the strain and stress distribution on jaw bone around the implant with different crown-root and different teeth high in teeth repairing, three-dimensional geometric model of the implant was created and analyzed through UG and finite element analysis software. Model came to workbench software after it was drawn and assembly by 3D mapping software of UG. Given material properties of the model, meshing, boundary conditions and forces applied for analysis. It was Obtained that the size and distribution of stress and strain about jaw bone and implant under different conditions. The influence of jaw bone and implant in different conditions was discussed. The main results of the study are as follows: different implant and crown-root, maximum stress with the crown-root increases, but the maximum stress is placid. Factor in the high thread where the maximum stress with high thread show an inverted "U" shape, the maximum strain with high thread becomes flat.

Background/Purpose Periodontally compromised abutments complicate the treatment plan of distal extension removable partial dentures. The objectives of this study were: (1) to determine if splinting a tooth with reduced bone height to a healthy one is beneficial to the weak one; (2) to investigate fixed splinting of two teeth (the first and second premolars) with various alveolar support levels on bone stress around the periodontal construction according to different crown to root ratios of the periodontally compromised abutment; and (3) to assess the efficiency of splinting in the presence of non-axial loads. Materials and methods Thirteen three-dimensional finite element models were designed that included the mandibular first and second premolars and the surrounding bone. Ten models were similar except for the alveolar bone height around the second premolar that had different amounts of bone resorption of 0-9 mm with splinted teeth. The last three were the same except for the teeth which were not splinted. A vertical force of 25 N was applied to each occlusal surface of the premolars. Finally, von Mises stress was evaluated at three points for all models. In the first stage, the efficiency of splinting was assessed. In the last stage, the effects of non-axial loads were evaluated in the splinted teeth models. Results In stage 1, it was shown that splinting could redirect the stresses to apical areas and prevented crestal bone from increased stress. In stage 2, the findings of von Mises stress in the apical area of the first premolar were almost the same in all models. In the apical area of the second premolar and the alveolar crest area, the bone stress increased when the height of the alveolar bone of the second premolar decreased. Stage 3 revealed that splinted teeth are efficient in carrying non-axial loads. Conclusion Splinting a very weak abutment to an adjacent healthy tooth might not be beneficial. The acceptable crown to root ratio for fixed splinting a weak abutment to an adjacent normal tooth was around 1.65-2.

Clinical significance In partially edentulous patients with considerable loss of tooth structure, it is recommended that a remaining tooth with a C/R ratio greater than approximately 1.5 should be used as an overdenture abutment to mini- mize lateral occlusal forces. Abstract Purpose: The clinical decision to use abutments for overdentures in cases with loss of tooth structure has not been fully assessed in relation to the periodontal condition. The aim of this study was to investigate the stresses around overdenture abutments with and without crown restoration for various bone heights. Methods: Three-dimensional finite element models of the mandibular right first and second premolars, a periodontal ligament, and one of five alveolar bone models of different heights were constructed. The crown-to-root ratios at the second premolar were 0.86 (Model A), 1.05 (Model B), 1.28 (Model C), 1.56 (Model D), and 1.96 (Model E). The second premolar root was also modeled without crown restoration. A single oblique load of 80 N at a 30-degree angle distal from the vertical axis was directed at the center of the oc- clusal or root surface of the second premolar. Results: The maximum stresses were observed at the distal cervical regions for all models. These increased as the crown-to-root ratio increased. The highest maximum stress in the cortical bone (35.8 MPa) was observed in Model E with crown restoration. In the re- gions near the overdenture abutments, the maximum stresses in the bone and the periodontal ligament were 33.9% to 61.7% lower than those observed near the crown restorations. Conclusion: The use of the premolar as an overden- ture abutment in cases with loss of tooth structure can effectively sustain the stress in the periodontal tissues, particularly under conditions of reduced bone height.

Crown-to-root ratio is intended to serve as an aid in predicting the prognosis of teeth. However, controversy persists as to its impact on diagnosis and treatment planning. This article critically reviews the available literature on the crown-to-root ratio assessment and criteria for evaluation of abutment use of periodontally compromised teeth. A Medline search was completed for the time period from 1966 to 2003, along with a manual search, to locate relevant peer-reviewed articles and textbooks published in English. Key words used were "crown-to-root ratio," "periodontal compromised dentition," "mobility," and "biomechanics." There was a dearth of evidence-based research on the topic. Although the use of the crown-to-root ratio in addition to other clinical indices may offer the best clinical predictors, no definitive recommendations could be ascertained.

Introduction In a clinical situation, an apically resected tooth is often accompanied by a varying degree of periodontal bone loss. The purpose of this study was to assess the influence of apical root resection combined with periodontal bone loss on the biomechanical response of a single-rooted tooth. Methods A basic intact model and a basic apically resected model of the upper central incisor were selected for the numerical analysis. From each basic model, 6 models were developed assuming different amounts of periodontal bone loss (0, 0.5, 1, 1.5, 2, and 3 mm). Maximum von Mises stress (σ max), maximum tooth displacement (ΔR max), and effective crown-to-root ratio (α) were calculated for each condition. Results There were only marginal differences (a 2.1% difference in σ max and a 16.9% difference in ΔR max) between the biomechanical responses of the intact model and the apically resected model when the tooth was supported by a normal periodontium. However, when destruction of the periodontium was assumed, the intact model and the apically resected model responded differently. The difference increased as the periodontal bone loss progressed, resulting in a 68.7% difference in σ max and a 56.3% difference in ΔR max when the periodontal bone loss increased to 3 mm (α = 0.48). Conclusions Although the biomechanical response of an apically resected tooth was relatively stable when the tooth was supported by a normal periodontium, the apically resected tooth showed a more deteriorated response compared with the intact tooth as the periodontal bone loss progressed.

Introduction Apical root resection is a biologically essential component in endodontic microsurgery. However, because it reduces the total root length and supported root surface, it changes the biomechanical response of the tooth. The purpose of this study was to analyze the biomechanical effect of apical root resection and to compare apical root resection with periodontal bone loss from a biomechanical standpoint. Methods Finite element models of the maxillary central incisor were reconstructed. First, preoperative and surgically treated models were generated to assess the factors altering the biomechanical response of the tooth. Then, apically resected models with different amounts of resection (3, 4, 5, 6, 7, and 8 mm) were created to estimate the clinically applicable limit of apical root resection. Periodontally destructed models with varying degrees of bone loss (0.5, 1, 1.5, 2, and 3 mm) were also created to compare the effect of apical root resection with periodontal bone loss. Stress distribution, tooth displacement, and effective crown-to-root ratio (α) were analyzed for each condition. Results Apical root resection did not significantly alter the maximum von Mises stress or tooth displacement until it reached 6 mm (α = 0.67) when the tooth was supported by normal periodontium. In contrast, periodontal bone loss had a greater impact on biomechanical response change compared with apical root resection. Conclusions For a tooth supported by normal periodontium, 3 mm of apical root resection (α = 1.07) appeared to be mechanically acceptable. The biomechanical influence of apical root resection was weak compared with that of periodontal bone loss.

Internal resorption is a rare lesion in permanent teeth. Managing perforating internal resorption is a great challenge for dentists. This report presents a successful surgical treatment of a maxillary central incisor that had extensive root perforation due to internal resorption. After unsuccessful nonsurgical approach, during surgical intervention apical part of the resorption defect was removed and the coronal part was filled with mineral trioxide aggregate. Three years later the tooth was symptom free with normal mobility and pocket depth despite unfavorable crown-to-root ratio. This case report have shown that surgical intervention and using mineral trioxide aggregate as root canal filling material in a tooth with extensive internal resorption and unfavorable crown-to-root ratio can be considered as a treatment option.

The definition of the crown-to-root ratio, its manifestation as a clinical problem, and associated problems were reviewed. Treatment possibilities were discussed in terms of plaque control, periodontal surgery, occlusal adjustment by selective grinding, splinting, restorative considerations, and extraction. The original guidelines for crown-to-root ratio in the selection of abutments were found to be exceptionally conservative and treatment limiting. New treatment modalities were considered in light of increased understanding of periodontal inflammation and its control. With inflammation controlled and with a carefully designed occlusion, some degree of mobility may be tolerated, thereby permitting the retention of teeth with minimal alveolar support.