Search Results (17)

Background: In this study, we aimed to investigate the association between a patient’s selection of implant treatment for a missing mandibular second molar and the magnitude of occlusal force, masticatory ability, mandibular morphology, and age before treatment intervention. Materials and Methods: We retrospectively assessed occlusal force, masticatory performance, and mandibular morphology in female patients who either selected or declined implant treatment for a missing unilateral mandibular second molar. Results: Thirty-three women (mean age of 56.1 ± 9.7 years) were divided into an implant treatment (IT) group and a no-treatment (NT) group. The IT group showed significantly higher occlusal force (p = 0.021 < 0.05), while masticatory performance and gonial angle demonstrated no significant difference. Conclusion: The IT group had significantly higher occlusal force, and age had no significant effect on it. Notably, masticatory performance in the IT group increased significantly with age (p = 0.047 < 0.05). Full article

Background/Objectives: Delayed tooth eruption (DTE) is a very challenging clinical situation, and the pathogenesis has been associated with local, systemic, and genetic factors. The aim of this presentation is to describe the management of such a case with delayed eruption of mandibular central incisors and canines. Methods: An 11-year-old female patient presented with DTE involving lower incisors (32, 42) and canines, seeking orthodontic treatment. Furthermore, lower permanent central incisors were congenitally missing while lower deciduous incisors were still in place. After a year-and-a-half of just monitoring the case and having suggested the extraction of deciduous first molars and canines, orthodontic treatment started with fixed appliances in the upper and lower jaw. First and second premolars gradually erupted after the precursor’s extraction. Lower canines and the two existing incisors were, after several months, surgically exposed and a gold chain apparatus was bonded on each one, while the closed eruption technique was chosen. A 0.17 × 0.25 stainless steel (SS) lingual wire, leaning on the buccal tubes of the lower molar bands and properly manipulated around them, was fitted in conjunction with the labial brackets and wires in order to facilitate the traction of the impacted teeth, which was carried out for one after the other using either an elastic chain or a second super-elastic wire. Results: All impacted teeth were finally restored to their proper place. The root of 71 did not present resorption, so the tooth was maintained in the lower arch while inter-proximal reduction was performed in the upper arch in the anterior region, in order to anticipate the lower missing incisor. Finally, a stable occlusion with proper contacts was achieved. Conclusions: Proper diagnosis, on-time extractions of deciduous teeth, and a well-designed treatment plan regarding space management and orthodontic traction of impacted teeth contributed to successful treatment outcomes in this DTE case. Full article

Background/Objectives: This study aimed to investigate the influence of the root canal morphology and various treatment variables on the outcomes of root canal treatments (RCTs) in mandibular second molars, assessed through cone-beam computed tomography (CBCT) imaging. Methods: A total of 150 CBCT images were examined, comprising 100 cases of persistent endodontic infections and 50 of previously treated root canals with normal apices in the mandibular second molars. CBCT was utilized to evaluate the root canal configuration, the radiographic quality of coronal restorations and treated canal systems, and the presence of periapical lesions. Statistical analyses were performed to explore the correlations between these factors. Results: The presence of a C-shaped root canal configuration did not demonstrate a significant correlation with periapical lesions (p = 0.05). Factors influencing endodontic treatment outcomes included missing canals (p = 0.018), underfilling or overfilling (p = 0.045), and inadequate coronal restoration (p = 0.006). Missing a canal was identified as the variable most significantly associated with periapical lesions (OR = 3.103). Inhomogeneous root canal obturation was more commonly observed in C-shaped root canals (p < 0.001). Conclusions: Regardless of the root canal morphology of mandibular second molars, successful RCT depends on thorough disinfection to eliminate any untreated canals, precise three-dimensional filling of the canals at the correct working length, and a securely sealed coronal restoration to prevent leakage. Full article

Background: Distal surface caries (DSC) has been associated with partially erupted impacted third molars. The purpose of this study was to compare the rates of DSC between populations that had undergone different third molar management strategies. Methods: Radiographs that had been taken during routine examinations of 1012, 251 and 250 patients in Manchester, Bucharest and Amsterdam, respectively, were evaluated. The following parameters were assessed: the state of the distal surface in the second mandibular molar, loss of periodontal support, impaction type of the third molar, contact point localization, and patients’ genders, ages and their cumulative history of dental health. Results: The rate of DSC in the second mandibular molar was 63.9%, 19.9% and 26.0% in the Manchester, Bucharest and Amsterdam populations, respectively. A loss of lamina dura of ≥2 mm, increased percentages of decayed, missing or filled teeth and male gender were risk factors in all three populations. All assessed parameters apart from the site of the mandible reached statistical significance in the Manchester sample (p < 0.001). The DSC rate was cumulative with increasing age in the Manchester population, in which third molars were strategically retained. Conclusions: The UK population, treated according to strict guidelines that limit the removal of third molars, had a statistically significant higher DSC prevalence rate (p < 0.001) than the Romanian or Dutch populations. The active surgical management of mandibular third molars seems to have the potential to reduce the DSC rate in the adjacent second molar. Full article

Background and purpose: Accurate instance segmentation of teeth in panoramic dental X-rays is a challenging task due to variations in tooth morphology and overlapping regions. In this study, we propose a new algorithm, for instance, segmentation of the different teeth in panoramic dental X-rays. Methods: An instance segmentation model was trained using the architecture of a Mask Region-based Convolutional Neural Network (Mask-RCNN). The data for the training, validation, and testing were taken from the Tuft dental database (1000 panoramic dental radiographs). The number of the predicted label was 52 (20 deciduous and 32 permanent). The size of the training, validation, and test sets were 760, 190, and 70 images, respectively, and the split was performed randomly. The model was trained for 300 epochs, using a batch size of 10, a base learning rate of 0.001, and a warm-up multistep learning rate scheduler (gamma = 0.1). Data augmentation was performed by changing the brightness, contrast, crop, and image size. The percentage of correctly detected teeth and Dice in the test set were used as the quality metrics for the model. Results: In the test set, the percentage of correctly classified teeth was 98.4%, while the Dice score was 0.87. For both the left mandibular central and lateral incisor permanent teeth, the Dice index result was 0.91 and the accuracy was 100%. For the permanent teeth right mandibular first molar, mandibular second molar, and third molar, the Dice indexes were 0.92, 0.93, and 0.78, respectively, with an accuracy of 100% for all three different teeth. For deciduous teeth, the Dice indexes for the right mandibular lateral incisor, right mandibular canine, and right mandibular first molar were 0.89, 0.91, and 0.85, respectively, with an accuracy of 100%. Conclusions: A successful instance segmentation model for teeth identification in panoramic dental X-ray was developed and validated. This model may help speed up and automate tasks like teeth counting and identifying specific missing teeth, improving the current clinical practice. Full article

(1) Background: Tooth agenesis is one of the most common developmental dental anomalies often affecting the maxillary incisors area and premolar regions. (2) Purpose: The aim of this study was to assess the prevalence and distribution of permanent tooth agenesis and the associated dental abnormalities among orthodontically treated children. (3) Materials and Methods: This study was carried out utilizing 3000 pretreatment records of children who underwent orthodontic treatment, 1780 (59%) females and 1220 (41%) males, aged 10–25 years (mean age 15 years). Tooth agenesis and other dental anomalies were surveyed using their panoramic radiographs, according to gender, pattern, and location. The level of statistical significance was set at p < 0.05 using t-test or Chi-Square tests. (4) Results: The total number of missing teeth, excluding third molars, was 518 (17%) found in 326 (11%) children. The majority were the maxillary lateral incisors, which was 176 teeth (34%) (p < 0.05). Of them, 111 (63%) were in females, and 65 (37%) were in males. The second most common missing tooth was mandibular second premolars, which was 137 teeth (26%), followed by missing 73 (14%) maxillary second premolars. Impacted teeth had the highest associated dental anomaly prevalence (14.3%), while transposition showed the lowest anomaly prevalence (0.5%). (5) Conclusions: A prevalence of 11% for tooth agenesis was detected in this study. More teeth were missing in the maxilla compare with the mandible. A significant association was found between missing maxillary lateral incisors and missing premolars (p < 0.05). Associated dental anomalies included an increased number of peg-shaped maxillary lateral incisors, palatally displaced and impacted maxillary canines, ectopic teeth, and infra-occluded (submerged) primary second molars. Full article

Objectives: To investigate the characteristics of spatial changes in molars and alveolar bone resorption among patients with loss of mandibular first molars. Methods: A total of 42 CBCT scans of patients with missing mandibular first molars (3 males, 33 females) and 42 CBCT scans of control subjects without loss of mandibular first molars (9 males, 27 females) were evaluated in this cross-sectional study. All images were standardized using the mandibular posterior tooth plane with Invivo software. The following indices regarding alveolar bone morphology were measured, including alveolar bone height, bone width, mesiodistal and buccolingual angulation of molars, overeruption of maxillary first molars, bone defects, and the capability of molar mesialization. Results: The vertical alveolar bone height in the missing group was reduced by 1.42 ± 0.70 mm, 1.31 ± 0.68, and 1.46 ± 0.85 mm on the buccal, middle, and lingual side, respectively (no differences among the three sides; p > 0.05). Alveolar bone width was reduced the greatest at the buccal CEJ level and the least at the lingual apex level. Mandibular second molar mesial tipping (with mean of the mesiodistal angulation = 57.47 ± 10.34°) and lingual tipping (with mean of the buccolingual angulation = 71.75 ± 8.34°) were observed. The mesial and distal cusps of maxillary first molars were extruded by 1.37 mm and 0.85 mm, respectively. Buccal and lingual defects of alveolar bone occurred at the CEJ, mid-root, and apex levels. Through 3D simulation, the second molar cannot be successfully mesialized into the missing tooth position, and the difference between the available and required distances for mesialization was the greatest at the CEJ level. The duration of tooth loss was significantly correlated with the mesio-distal angulation (R = −0.726, p < 0.001), buccal-lingual angulation (R = −0.528, p < 0.001) and the extrusion of the maxillary first molar (R = −0.334, p < 0.05). Conclusion: Both vertical and horizontal resorption of alveolar bone occurred. Mandibular second molars exhibit mesial and lingual tipping. Lingual root torque and uprighting of the second molars are needed for the success of molar protraction. Bone augmentation is indicated for severely resorbed alveolar bone. Full article

Objective: To evaluate the dental caries status and its association with tooth brushing frequency and previous dental visits among Arabian children. Methods: Arabian school children attend a specialty pediatric dental clinic at Majmaah University, Saudi Arabia. Only children of Saudi origin with primary dentition were included in the study, and only one examiner was involved in the assessment and data collection. The parents of children completed a questionnaire to investigate possible explanatory variables for caries status, including tooth brushing frequency and previous dental visits. Dental caries were diagnosed according to the criteria recommended by the World Health Organization (2013). The comparison performed was based on sex, age, tooth brushing frequency, and previous dental visits. The descriptive statistics were carried out using SPSS (version 21.0) with a p-value of <0.05 significance. Results: The study involved 268 Saudi children with a mean age of 4.6 ± 1.1 years. The caries prevalence was 78.8%, and the mean dmft was 5.82 ± 4.48, while the overall mean scores for decayed, missing, and filled were 3.903 ± 3.69, 1.18 ± 1.69, and 0.73 ± 1.35, respectively. The mean dmft scores for the <3 years, 3.1–6 years, and >6 years old children were found to be 1.74, 6.58, and 4.58, respectively. Among the children, the females reported higher dmf scores (7.51 ± 4.18) compared to males (4.97 ± 4.39) with a statistically significant difference (p < 0.001). Fifty percent of the children had tooth brushing habits of once daily, followed by never (22.4%), twice daily (15.7%), and rarely (11.2%) brushed their teeth. Statistically significant correlations were found between the children’s dental caries status, age, and dental visits, while sex and tooth brushing did not find a correlation. Conclusion: The prevalence of dental caries among Arabian preschool children was higher. Mandibular second molars were commonly affected by dental caries, while mandibular central incisors were less frequently affected. The child’s age and frequency of dental checkups were positively related to the prevalence of dental caries. Full article

(1) Background: tooth agenesis is a very common dental anomaly of the human dentition most often affecting the maxillary anterior region, mandibular and maxillary premolar regions. (2) Purpose: the present study was aimed to evaluate the prevalence and patterns between bilateral and unilateral tooth agenesis among orthodontic individuals and to illustrate the treatment options for missing teeth and the outcome. (3) Materials and methods: Pre-treatment records, photographs and radiographs, of 3000 consecutively treated orthodontic individuals from the post-graduate clinic of Tel Aviv University were surveyed to detect permanent tooth agenesis in either dental arch. The data was recorded according to gender, and location and quantified between unilateral and bilateral agenesis. Descriptive and comparative statistical analysis were performed with t-test and Chi-square test (p < 0.05). (4) Results: permanent teeth agenesis, excluding third molars, was found in 326 individuals (11%), 139 males (43%) and 187 females (57%). Of them, 59% were missing in the maxilla and (41%) were missing in the mandible. A higher prevalence rate of bilateral missing lateral incisors in the maxilla (62 cases), followed by bilateral missing second premolars in the mandible (44 cases) compared with unilateral missing teeth. (5) Conclusions: this study found an overall prevalence of missing permanent teeth in orthodontic patients to be 11%. The female: male prevalence ratio was roughly 3:2, with a greater tendency in the maxilla than in the mandible. A higher prevalence of bilateral missing maxillary lateral incisors and mandibular second premolar than unilateral missing teeth. Full article

(1) Introduction: Mandibular second molar (MM2) impaction is a relatively rare dental anomaly, but its early detection is imperative for orthodontic diagnosis and treatment. This study evaluates early radiographic characteristics of MM2 in the process of its impaction and the role of the third molar (MM3) in this process. (2) Materials and Methods: Panoramic radiographs of orthodontic patients of Chinese-American origin (n = 5575), age 9–15 years (mean 13.13) were examined for MM2 impactions and the presence of MM3. (3) Results: A total of 151 patients with 212 impacted MM2s were detected in the Chinese-American study group. Unilateral impactions were found more than bilateral and were distributed equally between the left and right sides. Mesial angulation of the impacted teeth was present in 92.7% of the cases, and MM3s were found adjacent to the impacted MM2s in 97.4% of the cases. (4) Conclusions: MM2 differential root developments with deficient mesial root lengths appeared to be the primary cause for MM2 impaction. Posterior crowding and arch length deficiency were contributing factors causing MM2 impaction. This impaction occurred early, before the third molar bud was developed. It sometimes occurred even when the third molar was congenitally missing. Nevertheless, the possible involvement of the third molar in MM2 impaction needs further investigation. Full article

The main objective was to examine the biomechanical behavior of the mandible under standardized trauma and to develop models of biomechanical responses when the mandible is subjected to various simulated impacts. A homogenous model based on the bone’s average mechanical properties was used. To simulate external loads on the mandible, forces on the chin, forces in an anteroposterior direction, and forces from the basilar edge were applied. To simulate mandibular biomechanics, we employed a model created in the ANSYS v19.0 software. The skull with the temporomandibular joint (TMJ) from the Grabcad website was used as the geometric mandibular model. We attempted to simulate the stresses developed in the mandible by impact forces. The amount of force (F) corresponded to the fall of a five-kilogram body (the head), from a height of two meters (F = 6666.7 N). The impact force was applied perpendicular to an arbitrary surface of an area of 10⁻³ m². Impact on the chin region and lateral impact on the mandible, from the basilar edge to the gonion were examined. The investigated clinical situations were mandibular complete dentition; jaw with missing mandibular molars; missing third molar and first and second premolars; missing canine, third molar, first and second premolars, and complete edentation. In a normal bite, the highest stress was on the TMJ area. In case of impact on the chin, in complete edentation, a mandibular fracture occurred; in case of impact on the gonion, all stress values exceed the limit value above which the mandible in the condyle area may fracture. Full article

The purpose of this research was to investigate and identify PAX9 gene variants in four Chinese families with non-syndromic tooth agenesis. We identified pathogenic gene variants by whole-exome sequencing (WES) and Sanger sequencing and then studied the effects of these variants on function by bioinformatics analysis and in vitro experiments. Four novel PAX9 heterozygous variants were identified: two missense variants (c.191G > T (p.G64V) and c.350T > G (p.V117G)) and two frameshift variants (c.352delC (p.S119Pfs*2) and c.648_649insC(p.Y217Lfs*100)). The bioinformatics analysis showed that these variants might be pathogenic. The tertiary structure analysis showed that these four variants could cause structural damage to PAX9 proteins. In vitro functional studies demonstrated that (1) the p.Y217Lfs*100 variant greatly affects mRNA stability, thereby affecting endogenous expression; (2) the p. S119Pfs* 2 variant impairs the subcellular localization of the nuclear expression of the wild-type PAX9 protein; and (3) the four variants (p.G64V, p.V117G, p.S119Pfs*2, and p.Y217Lfs*100) all significantly affect the downstream transcriptional activity of the BMP4 gene. In addition, we summarized and analyzed tooth missing positions caused by PAX9 variants and found that the maxillary second molar (84.11%) and mandibular second molar (84.11%) were the most affected tooth positions by summarizing and analyzing the PAX9-related non-syndromic tooth agenesis positions. Our results broaden the variant spectrum of the PAX9 gene related to non-syndromic tooth agenesis and provide useful information for future genetic counseling. Full article

Study Design: Autotransplantation, if possible, is a viable option for replacing a missing tooth when a donor tooth is available. The most typical tooth transplant is the transfer of a third molar to a first molar site. No immune reaction results from transplants of this nature. It restores the proprioceptive function and normal periodontal healing; thus, the patient can have a natural chewing feeling and natural biological response. Objective: This study aims to evaluate the prognosis of autotransplanted mandibular third molar and also to evaluate the cost effectiveness of the treatment performed when compared to the other treatment modalities for prosthetic rehabilitation. Methods: A prospective studywas done in theDepartment ofOral & Maxillofacial Surgery, Sardar Patel PostGraduate Institute of Dental &Medical Sciences, Lucknow,UP, India, with over 20 patients to evaluate the prognosis of autotransplanted mandibular third molars with complete root formation after atraumatic extraction of first or second mandibular molar, which were randomly selected irrespective of race, sex, caste, and socio-economic status. Regular clinical and radiographical examinations were performed over a period of 1 year and the patients were assessed for pain, swelling, infection, dry socket, periodontal pocket depth, ankylosis, root resorption, tooth mobility, and level of buccal bone in relation to cementoenamel junction (CEJ). Results: Eighteen out of 20 transplants were successful; only 2 mandibular transplants were extracted because of abnormal horizontal and axial mobility and the reason of failure was attributed to fact that the roots of transplant were short and conical and there was lack of alveolar bone height at the recipient site in one patient, while root resorption was the reason for failure of transplant in the other patient. Conclusions: This study assessed the efficacy of autotransplantation of molars and the viability of the procedure to replace unrestorable molar teeth; it also supports the hypothesis that transplantation of a mandibular third molar for replacement of a lost or seriously damaged molar tooth could be a reasonable alternative. Full article

The purpose of this study was to address the hypothesis that extreme outcomes of dental caries, such as edentulism or prematurely losing permanent teeth are associated with genetic variation in enamel-formation genes. After scanning 6206 individuals, samples of 330 were selected for this study. Tested phenotypes included patients who were edentulous by age 30, patients with missing first molars by age 30, patients with missing second molars by age 30, and caries-free patients. Fourteen single nucleotide polymorphisms were genotyped by TaqMan chemistry. The analyses of each phenotype were performed using the software PLINK with an alpha of 0.05. Nominal associations were found between rs12640848 in enamelin (p = 0.05), rs1784418 in matrix metallopeptidase 20 (p = 0.02), and rs5997096 in the tuftelin interacting protein 11 and being caries-free at the age of 60. When combining patients that were missing both first mandibular molars and missing both second mandibular molars, no associations were found. Matrix metallopeptidase 20, and tuftelin interacting protein 11 also showed trends for association with being caries-free. Genetic variation in TFIP11, MMP20, and ENAM may have a protective effect increasing the chances of individuals preserving their teeth caries-free over a lifetime. Full article

There has been an increase in utilizing 3D printers in dental restorations. The purpose of the study is to compare mechanical properties of 3D-printed prostheses to those of self-cured and/or computer-aided design-computer-aided manufacturing (CAD-CAM) restorations. A metal master typodont was prepared for the mandibular left sextant with implant analogs embedded at the first premolar and first molar positions with a missing second premolar. Three-unit provisional fixed dental prosthesis (FDP) was designed utilizing the 3Shape tooth library and forty-five uniform specimens were fabricated with different materials: self-cured poly(methyl methacrylate) (PMMA) (N = 15), milled PMMA CAD-CAM blocks (N = 15) and 3D-printed resin (N = 15). All specimens were tested using an Instron machine at a crosshead speed of 0.5 mm/min by an axial load on the occlusal surface of the second premolar pontic site. Statistical analysis was completed with Shapiro-Wilk, ANOVA and Tukey post-hoc tests. Mean fracture force was 300.61 N, 294.64 N and 408.49 N for self-cured PMMA, milled PMMA and 3D-printed resin, respectively. Mean force at FDP fracture of 3D-printed resin was significantly greater than the mean fracture force of either self-cured (p = 0.016, 95% CI [17.86, 197.91]) or milled (p = 0.010, 95% CI [23.83, 203.88]) PMMA. Full article