Euler-angle norms for tooth rotation, torque and tip.

INTRO: The aim of the current study was to develop and describe a new measuring system for the orientation of a tooth in a digitalized cast of a jaw and provide new angular values for the rotation, torque and tip of maxillary and mandibular teeth. METHODS: This retrospective cross-sectional study involved the utilization of a sub-group of extrinsic Euler-angles to derive optimal norm values per tooth in three different planes of orientation ('rotation', 'torque' and 'tip') by evaluating the digital representations of the teeth derived from a database containing over 17,500 patients. The process involved the entry of the .stl files of the jaw pairs into a fully automated software system (Smyl:Ai, Ulm, Germany) whereupon jaw alignment, teeth segmentation, landmark identification and visual validation of input files was conducted prior to calculation of the norm values for the three different planes of orientation. RESULTS: The digital scans in stereolithography (.STL)-file format of the upper and lower dentitions of 1914 individuals with optimal occlusion were chosen and evaluated. New mean (standard deviation) angular values were determined for the rotation, torque and tip of maxillary and mandibular teeth. CONCLUSION: The findings facilitate the reappraisal of rotation, torque and tip values currently acceptable as ideal. They will inform anthropologists and dental researchers about occlusion and alignment in orthodontic and non-orthodontic patients and provide baseline data for future studies. The methodology will also enable the evaluation of large numbers of data in relatively short timeframes.

Prevalence and Patterns of Positional Dental Anomalies in First Permanent Molars: Insights from a Study in Oradea, Romania.

Tooth position anomalies, influenced by both genetic and environmental factors, can significantly impact oral health and play a critical role in establishing proper occlusion. The aim of this study was to identify the most prevalent tooth position anomalies in first permanent molars among Romanian patients and to evaluate additional variables as well. This retrospective study utilized digital study models to identify all existing tooth position anomalies. The study included patients aged 12 to 40 years with complete permanent dentition. Axial changes (buccal tilting, oral tilting, mesial tilting, and distal tilting) as well as rotational changes (mesio-buccal rotation and disto-buccal rotation) were investigated. After applying the exclusion criteria, 103 patients remained in the study. Our findings revealed a notable prevalence of positional anomalies, with disto-buccal rotations being most common in upper molars (tooth 1.6-22.3%, tooth 2.6-31.1%) and oral tilting predominating in lower molars (tooth 3.6-6.8%, tooth 4.6-14.6%). Interestingly, neither gender nor malocclusion type significantly influenced the occurrence of tooth position anomalies. Symmetrical patterns in positional changes were observed, with patients having tooth position anomalies at 1.6 significantly more frequently associated with anomalies at 2.6. Similarly, anomalies at 3.6 were significantly more frequently associated with anomalies at 4.6. Additionally, for molars 2.6 and 3.6 on the left side, the differences were statistically significant, with patients having anomalies at 2.6 significantly more frequently associated with anomalies at 3.6. This pattern was not observed for the molars situated on the right side of the dental arches. While this study provides insights into positional anomalies in first permanent molars among the Romanian population, its retrospective design and focus on a specific demographic may limit generalizability. In conclusion, the study underscores the significant prevalence of positional anomalies in first permanent molars among adolescents and adults in Oradea, Romania. Early detection and targeted interventions are crucial to address these anomalies and improve orthodontic outcomes. Comprehensive assessment and treatment planning are essential to achieve optimal dental harmony and function. Further research is needed to elucidate the underlying factors contributing to these positional changes and their long-term impact on oral health and occlusal stability.

A cascading learning method with SegFormer for radiographic measurement of periodontal bone loss.

OBJECTIVE: Marginal alveolar bone loss is one of the key features of periodontitis and can be observed via panoramic radiographs. This study aimed to establish a cascading learning method with deep learning (DL) for precise radiographic bone loss (RBL) measurements at specific tooth positions. MATERIALS AND METHODS: Through the design of two tasks for tooth position recognition and tooth semantic segmentation using the SegFormer model, specific tooth's crown, intrabony portion, and suprabony portion of the roots were obtained. The RBL was subsequently measured by length through these three areas using the principal component analysis (PCA) principal axis. RESULTS: The average intersection over union (IoU) for the tooth position recognition task was 0.8906, with an F1-score of 0.9338. The average IoU for the tooth semantic segmentation task was 0.8465, with an F1-score of 0.9138. When the two tasks were combined, the average IoU was 0.7889, with an F1-score of 0.8674. The correlation coefficient between the RBL prediction results based on the PCA principal axis and the clinicians' measurements exceeded 0.85. Compared to those of the other two methods, the average precision of the predicted RBL was 0.7722, the average sensitivity was 0.7416, and the average F1-score was 0.7444. CONCLUSIONS: The method for predicting RBL using DL and PCA produced promising results, offering rapid and reliable auxiliary information for future periodontal disease diagnosis. CLINICAL RELEVANCE: Precise RBL measurements are important for periodontal diagnosis. The proposed RBL-SF can measure RBL at specific tooth positions and assign the bone loss stage. The ability of the RBL-SF to measure RBL at specific tooth positions can guide clinicians to a certain extent in the accurate diagnosis of periodontitis.

Correlation between Tooth Position Parameters and Apical Fenestration: A Cone-Beam Computed Tomography Study.

This study aimed to assess the relationship between apical fenestration-a defect in the alveolar bone involving the root apex-and tooth position in all tooth groups, excluding the third molars, utilizing cone-beam computed tomography (CBCT) images. A total of 800 CBCT scans (400 maxillary and 400 mandibular) from patients undergoing various treatments were examined by a single professional (radiologist and endodontist). Statistical analyses, including the chi-square test or Fisher's exact test, were conducted using R software 2.7.3 (R Foundation, Vienna, Austria). Results indicated a significant association (p ≤ 0.05) between apical fenestration and tooth position. In the upper teeth, apical fenestrations were notably present in the mesio-buccal (17.17%) and disto-buccal (11.07%) roots of the first molars. Conversely, apical fenestrations in the lower teeth were relatively less frequent. The study revealed a negative correlation between apical fenestration and mesial inclination, rotation, and extrusion in the upper teeth. However, a positive correlation was observed between apical fenestration and lingual inclination in the upper teeth. In conclusion, this study illuminates the distribution of apical fenestration and its correlation with tooth positions, offering insights into factors influencing this defect in dental anatomy. The findings enhance our understanding of nuanced relationships between tooth position and apical fenestration in the upper and lower dental arches.

Automatic recognition of teeth and periodontal bone loss measurement in digital radiographs using deep-learning artificial intelligence.

Background/purpose: Artificial Intelligence (AI) can optimize treatment approaches in dental healthcare due to its high level of accuracy and wide range of applications. This study seeks to propose a new deep learning (DL) ensemble model based on deep Convolutional Neural Network (CNN) algorithms to predict tooth position, detect shape, detect remaining interproximal bone level, and detect radiographic bone loss (RBL) using periapical and bitewing radiographs. Materials and methods: 270 patients from January 2015 to December 2020, and all images were deidentified without private information for this study. A total of 8000 periapical radiographs with 27,964 teeth were included for our model. AI algorithms utilizing the YOLOv5 model and VIA labeling platform, including VGG-16 and U-Net architecture, were created as a novel ensemble model. Results of AI analysis were compared with clinicians' assessments. Results: DL-trained ensemble model accuracy was approximately 90% for periapical radiographs. Accuracy for tooth position detection was 88.8%, tooth shape detection 86.3%, periodontal bone level detection 92.61% and radiographic bone loss detection 97.0%. AI models were superior to mean accuracy values from 76% to 78% when detection was performed by dentists. Conclusion: The proposed DL-trained ensemble model provides a critical cornerstone for radiographic detection and a valuable adjunct to periodontal diagnosis. High accuracy and reliability indicate model's strong potential to enhance clinical professional performance and build more efficient dental health services.

High prevalence of taurodontism in North China and its relevant factors: a retrospective cohort study.

OBJECTIVE: The purpose of this study was to investigate the prevalence and relevant factors of taurodontism in North China. METHODS: We retrospectively analysed the cone beam computed tomography (CBCT) of 1025 patients (496 male and 529 female) aged between 10 and 59 years. The crown-body/root (CB/R) ratios of the maxillary and mandibular molars were measured. The prevalence of hypotaurodontism, mesotaurodontism, and hypertaurodontism was then calculated and the incidence of taurodontism along with its relevant factors, was evaluated. RESULTS: The overall rate of taurodontism in North China was as high as 78.9%. If the third molars (opsigenes) were excluded, which have a big morphological variation from each other, the rate was 52.4%. The mean CB/R ratio of taurodontism differs from tooth position: maxillary mandibular third molars > maxillary third molars > maxillary second molars > maxillary first molars > mandibular second molars > mandibular first molars (P < 0.05). In addition, the 1025 patients were divided into different age groups, and it was found that the mean CB/R ratio decreased with age (P < 0.05). Moreover, the CB/R ratio of the mandibular first and second molars in female patients was higher than males (P < 0.05). CONCLUSION: This study revealed that taurodontism is widely prevalent in North China. The incidence of taurodontism increases the closer the tooth is to the back end of the dental arch, and quite a few of the maxillary and mandibular third molars teeth have tapered roots. And the taurodontism is decreased by age, as there were more affected female than male patients.

Ideal transverse position of mandibular first molars based on CBCT-derived alveolar bone coverage.

BACKGROUND: In orthodontic treatment, transverse arch width often needs to be adjusted to correct anomalies such as posterior crossbite. Ideal transverse arch width at the first molars enabling long-term stability and periodontal health, however, requires sufficient posttreatment bony coverage buccally and orally of the tooth roots. Thus, the aim of this retrospective study was to determine the physiological alveolar bone thickness at the buccal and oral roots of the first mandibular molars in the general population using human CBCT scans assessing local and gender-specific differences. METHODS: CBCTs of 124 random 11- to 55-year old patients (46 female, 78 male) were analysed retrospectively. Alveolar bone thickness was measured digitally at mesial and distal tooth roots of the first mandibular molars buccally and orally at different vertical positions (4 and 8 mm apically of the cement-enamel-junction CEJ). For each patient, the mean of corresponding measurements from left and right molars was used for analysis. RESULTS: All measurements were reliable, as proven by intrarater- and interrater-reliability-testing. On average, bone thickness increased from the mesial to the distal tooth root, as well as in apical and oral direction. These local differences in alveolar bone thickness were all highly significant at p < 0.0001. Women showed thicker bone buccally at the distal tooth root at 8 mm apically of the CEJ, as well as orally at both mesial and distal tooth roots 4 mm apically of the CEJ. CONCLUSIONS: The results of this study suggest that especially in buccal, mesial and gingival direction alveolar bone around mandibular first molars becomes thinner and hence the scope for orthodontic tooth movements is limited. Our results should aid assessing ideal transverse molar position based on alveolar bone coverage, although variations due to age may occur.

Clinical classification of tooth position in the alveolar bone housing with periodontal defects.

A new classification of tooth position in the alveolar bone housing, which indicates the width of alveolar bone for buccolingual direction, with bone defects caused by periodontal disease is proposed. This classification highlights the importance of tooth position in the alveolar bone housing in terms of the progression of the regenerative process and the factors that may affect the prognosis of compromised teeth after regenerative surgery. Tooth positions were divided into two groups: (i) The whole tooth is centrally positioned in the existing alveolar bone housing (Grade I) and (ii) A part of the tooth is exposed out of the existing alveolar bone housing (Grade II). Grade II is further divided into two subgroups according to situations encountered in clinical practice. The following subclasses are suggested: Subgroup A, where the alveolar bone housing is broader than the tooth, and Subgroup B, where the alveolar bone housing is narrower than the tooth. These subgroups represent a discrepancy between tooth size and alveolar bone dimensions in the buccolingual orientation. This classification could be useful for planning the correct regenerative treatment for each type of the tooth position in the alveolar bone housing with periodontal defects.

Tooth Position in Wind Instrument Players: Dentofacial Cephalometric Analysis.

BACKGROUND: Specific dentofacial characteristics in wind instrumentalists should be taken in consideration when analyzing physiological and anatomical issues regarding the musician's embouchure, posture, and biomechanics during musical performance. OBJECTIVES: To compare tooth cephalometric characteristics between wind instrument players and string players (overjet, overbite, lower facial height, facial convexity, lower incisor inclination, and interincisal angle). METHODS: In total, 48 wind instrumentalists (67%) and 24 string instrumentalists (33%). These musicians performed lateral tele-radiography and the correspondent linear and angular measurements of the dentofacial cephalometric analysis. Statistical comparison of wind and string instrumentalists was made by using an independent t-test. RESULTS: Small variations on the analyzed parameters were found between the wind and string instrument groups. Based on the cephalometric analysis the variable interincisal angle was statistically significant (p < 0.05), when comparing the wind and string instrument group. CONCLUSIONS: Knowledge of the overjet and overbite value permits a substantial analysis on the tooth position of wind instrument players, where both of these parameters are increased and greater than the norm value. The cephalometry was an added value on the interpretation of possible factors that lead to the position of the central incisors of wind instruments. Till some extent in this group of musicians the applied forces during the embouchure mechanism on the anterior teeth and the existing perioral forces promote an equilibrium on the vector of forces. This study findings demonstrate that when evaluating the two samples, wind and string instruments there are different dentofacial configurations, however the only statistically significant differences that were found are related to the interincisal angle (p < 0.05).

Impact of Tooth Loss Position on Oral Health-Related Quality of Life in Adults Treated in the Community.

BACKGROUND: Tooth loss is known to have negative effects on both functional and psychological oral health-related quality of life (OHRQoL), but the impact of the position of the tooth loss (i.e. anterior or posterior) on the different psychosocial dimensions of OHRQoL has yet to be examined. Here, we examined how the position of lost teeth impacts the different dimensions of OHRQoL. METHODS: This was a cross-sectional epidemiological study of adults aged 18 years and older attending routine examinations at primary care dental centers in Jeddah, Kingdom of Saudi Arabia. Demographic information was collected, and OHRQoL was assessed using the Oral Health Impact Profile-14 (OHIP-14) (Arabic form). Differences in total and subdomain OHIP-14 scores between individuals without tooth loss and those with ≥1 anterior or posterior missing teeth were assessed using Student's t-test, and analysis of covariance was used to assess the association between the presence and absence of missing teeth in each compartment and total and subdomain OHIP-14 scores after controlling for age, gender, and income. RESULTS: The overall prevalence of tooth loss was 76%. In multivariate analysis controlling for age, gender, and income as covariates, anterior missing teeth were significantly associated with higher OHIP-14 total, physical pain, physical disability, psychological disability, and social disability scores, accounting for 6%-12% of the score variance. However, posterior missing teeth were only associated with total OHIP-14 and functional limitations domain scores, accounting for 6% and 7% of the variance, respectively. CONCLUSIONS: Here, we show for the first time the impact of the location of missing teeth on different OHRQoL dimensions. Anterior tooth loss has a wide-ranging impact on both physical and psychosocial functioning compared to posterior tooth loss, suggesting that anterior tooth restoration should be prioritized when treatment planning. The position of lost teeth must be considered in addition to the number of losses when examining the impact of tooth loss and its treatment on OHRQoL.

Improvement of embouchure after correction of irregular front teeth: the case of a professional French horn player.

A professional horn player visited his dentist after experiencing pain. His protruding lower incisor was causing soreness of the lower lip, and upper anterior crowding was irritating the centre of the upper lip. These irregularities affected the patient's ability to produce an optimal sound. During treatment, the lower anterior teeth were aligned using a fixed appliance and the irregularity in the upper front teeth was reduced with a composite veneer. The hornist experienced considerable improvements after these two dental corrections.

Ectopically Positioned Tooth Piercing the Philtrum.

A variety of eruption disturbances arise during the transitional dentition period, which can be broadly classified as disturbances related to time and disturbances related to position. The occurrence of ectopic eruption is relatively common, but ectopically positioned tooth piercing the philtrum is a rare clinical presentation. This is a case report of a 70-year-old female who presented with the chief complaint of an abnormally positioned tooth piercing out from the upper lip to the Department of Oral and Maxillofacial Surgery, Karnavati School of Dentistry, Uvarsad, Gandhinagar, Gujarat, India. As per the patient's history, labially erupted tooth was piercing the philtrum for 60 years and it was visible extraorally from the philtrum and was painful.

Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study.

OBJECTIVE: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. METHODS: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. RESULTS: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. CONCLUSIONS: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

Differences in the mandibular premolar positions in Angle Class I subjects with different vertical facial types: A cone-beam computed tomography study / 대한치과교정학회지

OBJECTIVE: To compare the positions of the mandibular premolars in Angle Class I subjects according to vertical facial type. The results will provide a theoretical basis for predicting effective tooth movement in orthodontic treatment. METHODS: Cephalometric parameters were determined using cone-beam computed tomography in 120 Angle Class I subjects. Subjects were categorized as short, normal, and long face types according to the Frankfort mandibular angle. Parameters indicating the position of the mandibular right premolars and the mandible were also measured. RESULTS: The angle between the mandibular first premolar axis and buccal cortex, the distance between the root apex and buccal cortex, angle of vestibularization, arc of vestibularization, and root apex maximum movable distance were significantly greater in the short face type than in the long and norm face types. The angle between the mandibular second premolar axis and buccal cortex, the distance from root apex to buccal cortex, and the arc of vestibularization were significantly greater in the short face type than in the normal face type. CONCLUSIONS: There are significant differences in the mandibular premolar positions in Class I subjects according to vertical facial type.

Prognostic factors of clinical outcomes in endodontic microsurgery: a prospective study.

INTRODUCTION: This prospective study examined the potential prognostic factors of endodontic microsurgery and compared the predictors of an isolated endodontic lesion with those of both an isolated endodontic lesion and an endodontic-periodontal lesion. METHODS: Data were collected from the Microscope Center of the Department of Conservative Dentistry at the Dental College of Yonsei University, Seoul, Korea, between March 2001 and March 2011. A total number of 584 teeth were included, and all clinical procedures were performed by a single operator (E.K.). The evaluation was performed at least 1 year after surgery. For statistical analysis of the predisposing factors, the chi-square test and logistic regression were performed. RESULTS: Of the 584 cases treated, 431 cases came for recall after a period of at least 12 months. Sex (female), tooth position (anterior), arch type (maxilla), and lesion type (isolated endodontic lesion) were found to have a positive effect on surgical outcome. With regards to isolated endodontic lesions, the tooth position (anterior), arch type (maxilla), and type of restoration (single/splinted crown, short bridge, and removable partial denture abutment) were found to be pure positive predictors. CONCLUSIONS: In endodontic microsurgery, it is likely that preoperative factors, particularly the tooth position and arch type, have a greater influence on the healing outcome than intra- and post-operative factors.

Success and failure of endodontic microsurgery / 대한치과보존학회지

In current endodontic practice, introduction of operating microscope, ultrasonic instruments, and microinstruments has induced a big change in the field of surgical retreatment. In this study, we aimed to offer key steps of endodontic microsurgery procedure compared with traditional root-end surgery, and to evaluate factors influencing success and failure based on published articles. Endodontic microsurgery is a surgical procedure performed with the aid of a microscope, ultrasonic instruments and modern microsurgical instruments. The microscope provides magnification and illumination - essential for identifying minute details of the apical anatomy. Ultrasonic instruments facilitate the precise root-end preparation that is within the anatomical space of the canal. Modern endodontics can therefore be performed with precision and predictability, thus eliminating the disadvantages inherent in traditional periapical surgery such as large osteotomy, beveled apicoectomy, inaccurate root-end preparation and the inability to observe isthmus. Factors influencing the outcomes of endodontic microsurgery may be diverse, but standardization of procedures can minimize its range. Among patient and tooth-related factors, periodontal status and tooth position are known to be prognostic, but there are only few articles concerning this matter. High-evidence randomized clinical trials or prospective cohort studies are needed to confirm these findings.

A study on the postoperative stability of occiusal plane in orthognathic surgery patients depending on the difference of oclusal plane / 대한치과교정학회지

Surgical-orthodontic treatment is performed for the skeletal Class Ill patients with no remaining growth and too big a skeletal discrepancy for camouflage treatment, and two jaw surgery is needed in order to have maximum effect in such patients. In two jaw surgery cases, surgical alteration of the occlusal plane is necessary to establish optimal function, esthetics and postoperative sabihty, therefore the establishment of the ocdusal plane is essential in diagnosis and treatment. The object of this study is to evaluate the stability of the indiviual ideal occlusal plane bsaed on the architectural and structural craniofacial analysis of Delaires. Thus, the subjects of this study were 48 patients who underwent two jaw surgery, and divided in two groups. Each group were composed of 24patients, A group were operated with ideal occlusal plane and B group were not Two groups were compared at the preoperative, immediate postoperative (average 4.3davs), and long-term postoperative (average 1.3years) lateral cephalometric radiographs. The following results wen obtained: 1. There was no significance in occlusal plane angulation between T(2) and T(3) Average long term follow-up changes of occlusal plane angle were 0.24degrees+/-2.43, with FH plane and O.15degrees+/-2.16degrees with SIN plane in all 48 patients. These results demonstrated that the occlusal plane after two jaw surgery in skeletal Class III malocclusion was stable. 2. There was no significance in postoperative stability of occlusal plane between A and B group. 3. There was no significance in postoperative stability of occlusal plane depending on surgeon and operative method within each group. 4. The postoperative changes of occlusal plane were. correlated to the postoperative changes of jaw rather than tooth position. 5. There was no correlation between the postoperative changes of occlusal plane and maxillary impaction and mandibular setback with surgery.