Aspects of Occlusal Recordings Performed with the T-Scan System and with the Medit Intraoral Scanner.

INTRODUCTION: Dental occlusion refers to the static and dynamic relationships that are established between the teeth of the two arches and is an important factor in the homeostasis of the dento-maxillary system. The objective of the present study was to compare two digital occlusal analysis systems: the T-Scan III system and the Medit I600 intraoral scanner. MATERIALS AND METHODS: The study was carried out on 20 students from the Faculty of Dental Medicine Craiova, whose dental occlusion was assessed with the T-Scan III system and with the Medit I600 intraoral scanner. Dental occlusion was assessed in the maximum intercuspation position, the edge-to-edge protrusion position, and the edge-to-edge position in right and left laterotrusion. The images of the 2D occlusal contact areas obtained by both methods were converted to .jpeg format and then transferred to Adobe Photoshop CS6 2021 (Adobe Systems, San Jose, CA, USA) for comparison. The recorded data were statistically processed. RESULTS: Analyzing the data provided by the two digital occlusal analysis systems, it was found that the T-Scan III system provided data related to the amplitude of the occlusal forces, the surface on which they were distributed (the contact surface), the dynamics of the occlusal contacts, and the proportion in which they were distributed at the level of the two hemiarches, and the Medit I600 intraoral scanner performed an evaluation of the occlusal interface of the two arches, highlighting the extent of the contact areas with the degree of overlapping of the occlusal components. Although both methods of occlusal analysis recorded the highest values for the maximum intercuspation position, the results could not be compared. CONCLUSIONS: The two digital systems provide different data in occlusal analysis. As the T-Scan III system is considered the gold standard for occlusal analysis, more studies are needed to understand the data provided by the Medit I600 intraoral scanner and their significance.

Removal of fiber post under the guidance of digital guide plate and one-piece glass fiber posts-and-cores repair: a clinical report.

This study explores the potential application of computer aided design (CAD)/computer aided manufac-turing (CAM) for one-piece glass fiber posts and cores in restoring tooth defects post-removal of a broken fiber post using a digital guide plate. This paper reports a fractured left upper incisor fiber post removed using a customized needle and digital guide plate. Following root canal retreatment, CAD/CAM integrated fiber post-core and zirconia full crown restoration were completed. The occlusion testing was conducted using the T-Scan Ⅲ system. This study offers insights for managing secondary repair after fiber post fractures.

Evaluation of the contribution of different groups of teeth to occlusion of patients with symptoms of temporomandibular disorders.

PURPOSE: The purpose of this study was to analyse the distribution of occlusal forces in the dental arches released during tooth clenching in patients with symptoms of temporomandibular disorders, and to analyse the age and gender structure of the patients in the study group and the control group. MATERIALS AND METHOD: The study was carried out on a group of 58 patients, of both genders, aged 18-40 years, with full dental arches, who presented for treatment at the Prosthodontics Clinic of the University Dental Clinic in Kraków due to symptoms of temporomandibular disorders. The patients were divided into two groups. The first group (study group) comprised 26 patients with painful temporomandibular disorders, while the second group (control group) comprised 32 patients without pain. The study only included patients over 18 years of age, with full dental arches with symptoms of temporomandibular disorders. All patients underwent a basic dental examination and a specialized functional examination of the masticatory organ. A T-Scan III-Novus instrument with electronic occlusal articulation paper was used to assess the distribution of occlusal contacts. RESULTS: In the study, women (43) were a larger group than men (15). Statistically significant values for the percentage distribution of occlusal contacts were obtained in group of women in the study group on the right and left side, in the area of molars and premolars. In the analysis of the percentage distribution of occlusal contacts in both the study and control groups, it can be seen that the first molars (teeth 16 and 26) showed a larger percentage range of values than the other teeth. The smallest values can be observed on the second incisal teeth and on the canines. CONCLUSIONS: The first molars are, in the majority of patients, the teeth on which the strongest occlusal contacts are generated. Excessive participation of incisal teeth in occlusion might influence the development of the pain form of TMD. In order to determine whether there is a correlation between an uneven distribution of occlusal contacts and TMD pain, studies on larger numbers of patients are needed. © 2024 Australian Dental Association.

In vivo evaluation of T-Scan in quantifying occlusal contact.

BACKGROUND: The T-scan system has been used previously to analyse occlusion, but the quantitative analysis of occlusal contact by T-Scan system has yet to be reported. OBJECTIVES: To evaluate the reliability and validity of T-Scan system for quantitatively measuring occlusal contact area and occlusal contact number. METHODS: Twenty-two individuals with normal occlusion, 11 men and 11 women, were recruited for the study. Two occlusal analysis methods, including silicone transmission analysis method (STA) and T-Scan occlusion analysis method (TSO), were used to make quantitative analysis to measure occlusal contact area (OCA) and occlusal contact number (OCN). A test-retest check was performed with an interval of 2 weeks. The values of intraclass correlation coefficients (ICC) between test-retest of each method were calculated for reliability evaluation. Pearson correlations analysis, paired t-tests, regression analysis and Bland-Altman analysis were performed for validity evaluation. RESULTS: The ICC values of STA were greater than those of TSO for OCA while for OCN, ICC values of TSO were greater than STA. The higher OCA and OCN values were found in TSO compared with STA. Pearson's correlation coefficient indicated strong relations between TSO and STA (0.730-0.812) for OCA, while good relations between then (0.569-0.583) for OCN. Paired t-test showed a significant difference between the OCA and OCN values between TSO and STA. Bland-Altman analysis showed good agreement between OCA and OCN values of TSO and STA both in men and women. Regression analysis identified a linear correlation between OCA values obtained from these two methods. CONCLUSIONS: T-Scan method showed strong reliability for measuring OCA and OCN quantitatively. Strong correlations were found between OCA values from TSO and STA method, but the validity of TSO for measuring OCN needs to be promoted. CLINICAL SIGNIFICANCE: T-Scan system demonstrates good potential in quantitative analysis of occlusion, which will expand its clinical application.

Reference values and reliability of occlusal force distribution and occlusal time measured by the T-Scan system in adults with healthy dentition.

PURPOSE: Reference values of occlusal characteristics are needed to interpret the data obtained using the T-Scan System. This study aimed to establish reference values for and to assess the reliability of, occlusal force distribution in the maximal intercuspal position and the occlusion time in young adults with healthy dentition. MATERIALS AND METHODS: In total 178 adults with natural dentition participated in this retrospective cross-sectional study, of whom 76 performed a retest session. Several occlusal recordings were obtained from each participant using the T-Scan system while asking them to bite two or three consecutive times (multi-bite) or only once (single-bite) at the maximal intercuspal position. The lateral and anteroposterior occlusal force distribution were determined as percentages in the right and posterior teeth . Occlusion time was measured in seconds. After the occlusal force distribution and occlusion time percentiles were calculated, reliability was assessed by the intraclass correlation coefficient. RESULTS: The 5th-95th percentiles for occlusal force distribution were 34%-67% on the right teeth and 55%-94% on the posterior teeth. The 90th percentile for multi-bite occlusion time was 0.17 s and for single-bite occlusion time was 0.27 s. The intraclass correlation coefficients for lateral occlusal force distribution, anteroposterior occlusal force distribution, multi-bite occlusion time, and single-bite occlusion time were 0.70, 0.68, 0.58, and 0.67, respectively. CONCLUSIONS: This study generated reference values for key occlusal characteristics (occlusal force distribution and occlusion time) when using the T-Scan system. These values showed moderate reliability.

Use of T-Scan III in analyzing occlusal changes in molar fixed denture placement.

BACKGROUND: This study aims to analyze the longitudinal variation of occlusal force distribution prior to and after fixed restoration for molar full-crowns with T-SCAN III which provide reference for occlusal adjustment and long-term maintenance. METHODS: We enrolled a total of 20 patients who received conventional restorative treatment for molars. The occlusion examination was conducted in 3 stages (before placement, immediately after placement, and 3 months after placement) using T-SCAN III (Tekscan South Boston, MA, USA, 10.0) to examine and measure the occlusal contact areas of the full dentition. RESULTS: The results indicated that the occlusal force distribution in the molar region of the patients changed before and after the fixed restoration, but the percentages of occlusal force in the dental arch of the molar did not differ significantly before and after the restoration (P > 0.05). Three months after the fixed restoration, the percentage of occlusal force in the restored dental arches of lateral teeth increased significantly (P < 0.05). CONCLUSION: The results of this study indicated that the occlusal forces of the patients changed with tooth movement and adaptation, which is mainly reflected in the increasing occlusal force. Quantitative occlusal force analysis using T-SCAN III occlusal analyzer can provide more objective and accurate data to effectively guide clinical occlusion adjustments.

Clinical applications of the T-Scan quantitative digital occlusal analysis technology: a systematic review.

STATEMENT OF THE PROBLEM: Occlusion is associated with all disciplines of dentistry and plays a major role in the longevity of both implant- and tooth-borne restorations. Achieving occlusal harmony ensures balance is established between the dental and myofascial structures, which can be measurably established to high numerical tolerances with the T-Scan digital occlusal analysis system. PURPOSE: To describe and evaluate the known and proven applications of T-Scan digital occlusal analysis in various dental practice disciplines through a systematic review of the literature. MATERIALS AND METHODS: An electronic, English-language PubMed/MEDLINE and Cochrane Central Registry of Controlled Trials database search using the keywords "T-Scan," "TMD," "Occlusion," "Implant Protected Occlusion," and "Orthodontics" was conducted without any date restrictions. The related journal findings were hand searched to determine studies that met the eligibility criteria for inclusion in the present systematic review. RESULTS: The PubMed/MEDLINE search identified 423 articles. After removing duplicates, the titles and abstracts of the remaining 421 studies were screened. 274 ineligible articles were excluded, leaving 147 articles. Of those, 33 articles were not in English, 27 full-text articles were not available, 4 were comments and letters to editors, 1 was a review, and 2 described techniques. A total of 86 articles met the eligibility criteria for inclusion. CONCLUSION: Much scientific evidence supports the use of T-Scan, as it measures relative occlusal contact forces and the time sequence durations of occlusal contacts objectively, accurately, and repeatedly for improved treatment outcomes. The system's hardware, sensor, and software evolution from T-Scan I to today's T-Scan 10 Novus system has overcome early sensor and system drawbacks to improve the clinical performance of T-Scan in many disciplines of dental medicine.

Evaluation of occlusal bite force distribution by T-Scan in orthodontic patients with different occlusal characteristics: a cross sectional-observational study.

BACKGROUND: The aim of orthodontic treatment, apart from esthetic and functional corrections, is uniform force distribution. Hence Occlusal analysis using a T scan gives scope for a precisely targeted treatment plan. The T-scan evaluation of occlusal force, time, and location of contacts from initial occlusal contact to maximum intercuspation enables the orthodontist to sequentially balance the occlusal forces on the right and left sides through specific treatment plan options. OBJECTIVE: The current study aimed to determine the force distribution in the different individuals by using a T-Scan as well as the net discrepancies of forces generated at a maximum intercuspation position in the first molar region between the left and right sides of the mouth. METHODS: This is a descriptive-correlational study that was carried out in Ras Al Khaimah College of Dental Sciences clinics and Ajman University clinics from January 2020 to September 2022 by using the convenience sampling technique. The T-scan III Novus was employed in this investigation to record multi-bite scans for several patients. T-scan was utilised to examine various malocclusions. RESULTS: The present study consisted of 158 participants. Analysis of Variance (ANOVA) showed that there is a statistically significant difference in the percentage of force between the three types of malocclusions (I, II, and III) on the right molar side (B-16 and B-46) (p < 0.05). Moreover, the overall discrepancy showed a statistically significant difference in the three types of malocclusion classifications (p < 0.05). On the other hand, there was no statistically significant difference in the percentage of force between B-26 and B-36 (p > 0.05). Post hoc analysis showed a statistically significant difference in the percentage of force between malocclusion classes I and III on the right molar, with a mean difference of 4.11190 (p < 0.05). Similarly, there was a statistically significant difference in B-46 between Malocclusion Classes I and II, 4.01806 (p < 0.05). Additionally, post hoc analysis showed a statistically significant difference between malocclusion classes I and III, with a mean difference of -4.79841 (p < 0.05) on the right molar. CONCLUSION: The T-Scan is a useful tool for assessing occlusal discrepancies and can be helpful during treatment planning and follow-up, especially for orthognathic surgery patients. A T-scan could be used in orthodontic therapy in a simple and efficient way. Also, it turned out to be a useful tool for diagnosing problems and gave us new information about how therapies work. In this study, T-Scan showed that it can measure occlusal forces in timing in an objective, accurate, and repeated manner. The current study found that T-Scan was better able to report the difference in the percentage of force on the right molar side than on the left side.

An In Vivo Study Using T-scan III Occlusal Analysis System: Does the Extraction Pattern Affect the Final Occlusion in Orthodontics?

BACKGROUND: The assessment of an orthodontic patient's occlusion throughout the treatment and after debonding permits the orthodontist to improve functional occlusion through interventional tooth movements, thus rendering the overall treatment more efficient in terms of stability and masticatory efficiency. This study aimed to evaluate the effect of four first premolar extractions during orthodontic treatment on the distribution of bite force using the T-scan III system (Tekscan Inc., Boston, MA). OBJECTIVE: We aim to evaluate the effect of four first premolar extractions during orthodontic treatment on bite force distribution. METHODS: Ten patients (mean age: 16 ± 2.72 years), who would be treated orthodontically with four first premolar extractions to treat their teeth crowding, were selected for this study. The T-scan III system was utilized to measure the occlusal bite force of the patients before and after treatment, and the findings were compared. RESULTS: There was a non-statistically significant decrease in the occlusal bite force's mean in the arch's anterior segment from 24.45% (± 8.50%) to 14.25% (± 12.93%) after the orthodontic treatment. A non-statistically significant increase in the occlusal bite force in the posterior right segment of the arch from 37.64% (± 18.13%) to 41.65% (± 11.52%) was found after the treatment. The occlusal bite force in the posterior left segment of the arch increased insignificantly from 30.53% (± 20.00%) to 43.95% (± 13.22%). There was an even distribution of bite force on both sides of the arch by the end of the treatment. CONCLUSIONS: Orthodontic treatment helps to achieve a functional occlusal balance by assisting in the uniform distribution of biting force on both sides of the arch. There was no statistically significant change in the distribution of bite force recordings collected before and after orthodontic treatment, indicating that the removal of the four first premolar teeth does not impact the functional aspect of occlusion. The T-scan III system serves as an essential guide during orthodontic treatment to monitor occlusal changes.

T-scans in implant procedures.

T scans are a breakthrough in technology which allows the user to accurately analyze the occlusion of a patient with minimal to zero errors. They are used during prosthodontic rehabilitation to map out the patient's occlusion to plan for replacements. Such a high advancement in technology has a backdraw. The cost of the equipment is a concern for simple dental practitioners. There are no large scale studies using T scans in determining the occlusion. Therefore, it is of interest to analyze the use of T scans in determining the percentage of contact in patients with dental implants. This retrospective analysis was done at the Saveetha University hospital set up where patients undergoing prosthesis fabrication for implants were included. Details like their age, gender and the percentage of contact of the implant and percentage of contact on the adjacent tooth were recorded. These details were tabulated and imported to IBM SPSS version 23 for statistical analysis. Chi square test was used to analyze comparable variables. 22 patients were analyzed, the mean percentage of contact of implants was found to be 7.45±;9.01 and the mean percentage of contact of adjacent teeth was found to be 10.14±6.7. Thus, T scan is an efficient method in recording the dynamic occlusal contacts of a patient. The use of T scan reveals data pertaining to individual tooth but in the present study there is no statistical significance in terms of exact values comparing implant contact to adjacent tooth contact. Further studies are needed with relation to timing and contact surface of implant prosthesis.

Changes in the distribution of occlusal forces in the course of the orthodontic retention phase : A prospective cohort study.

PURPOSE: Aim of the present study was to assess the relative distribution of occlusal forces after orthodontic treatment and during the first 3 months of the retention phase using a computerized occlusal analysis system (T-Scan, Tekscan Inc., Norwood, MA, USA). MATERIALS AND METHODS: A total of 52 patients were included in this prospective cohort study and underwent analysis of occlusal forces on the level of tooth, jaw-half, and -quadrant during a 3-month period. Furthermore, differences between three retention protocols (group I: removable appliances in both jaws; group II: fixed 3-3 lingual retainers in both jaws; group III: removable appliance in the maxilla and fixed 3-3 lingual retainer in mandible) were assessed with Wilcoxon signed-rank tests at 5%. RESULTS: Directly after debonding, measured forces distribution were similar to published references for untreated samples. In the following, no significant difference was found between retention protocols II and III with regard to the asymmetry of the anterior occlusal forces. Both groups maintained an asymmetric force distribution in the anterior segment during the study period. There was also no difference between groups II and III in the distribution of occlusal forces for the posterior segments. Both retention concepts kept the symmetrical distribution of occlusal forces stable over the observation period. The retention concept of group I demonstrated a symmetrical distribution of occlusal forces in the anterior segment after debonding and this remained stable during the 3­month period. In the posterior segment, no improvement of the initially asymmetric masticatory force distribution could be observed. CONCLUSIONS: All three studied retention protocols showed stability in retaining their original symmetrical or asymmetrical occlusal force distribution posteriorly/anteriorly during the 3­month observation period. Therefore, an even distribution of occlusal forces should be the aim of the finishing phase, as no relative benefit of any single retention scheme in terms of post-debond improvement during the retention phase was seen.

Evaluation of occlusal forces using T scan analysis following mandibular fracture fixation.

Introduction: Mandible receives maximum impact following maxillofacial trauma. The dentate segment in particular is of importance as it has a direct bearing on the occlusive forces. The studies that have been carried out are either based on crude clinical evaluations or make use of elaborate and labor-intensive techniques. This study made use of T-scan analysis for objective identification of occlusive forces following mandibular fracture fixation. Materials and Methods: Eighty clinic-radiologically diagnosed cases of dentate segments of the mandible were considered, after random sampling method. The occlusion analysis was done by use of a T scan to obtain Relatively Occlusal Force. The procedure was repeated at 04-, 24-, 36-, and 48-weeks intervals. The data was recorded on Excel Spreadsheet (Microsoft Inc) and analysis was done using SPSS software. Results: The cases were predominantly males with a homogenous distribution of cases of age. The age versus gender distribution was more skewed in the female subgroup with a higher kurtosis value. Both evaluative (Pearson's) and inferential (paired t) tests were applied to reason the study. It was observed that the ROF values decreased in values as compared to pre-operative/post-treatment (Difference of Mean = 2.19, SE = 2.13) compared to 4 (Difference of Mean = -0.40 SE = 0.188),24 (Difference of Mean = -1.22, SE = 0.24) and 36 (Difference of Mean = -3.24, SE = 0.30) weeks, which however surpassed the pre-operative levels at 48 weeks post-operative period. This is suggestive of impending muscular imbalance in the initial periods. The surpass of 48 weeks may be due to optimal forces that were their pre-trauma. Conclusion: Mandibular fracture fixation is the most widely used and also a time-tested modality in the management of mandibular trauma. The evaluation of occlusive forces needs an understanding of their behavior following such fixation. The present study used T-scan analysis to objectify such forces and added extra insight apart from clinical evaluations of tooth contact and parafunctional movements.

Computerized dynamic occlusal analysis and its correlation with static characters in post-orthodontic patients using the T-Scan system and the ABO objective grading system.

OBJECTIVES: This study was conducted to detect the overall performance of both static and dynamic occlusion in post-orthodontic patients using quantified methods, and to ascertain the correlation between the two states of occlusion. MATERIALS AND METHODS: A total of 112 consecutive patients evaluated by ABO-OGS were included in this study. Based on the pre-treatment Angle's classification of the malocclusion, samples were divided into four groups. After removing orthodontic appliances, each patients underwent the American Board of Orthodontic objective grading system (ABO-OGS) and T-Scan evaluations. All the scores were compared within these groups. Statistical evaluation included reliability tests, multivariate ANOVA, and correlation analyses (p < 0.05 was considered significant). RESULTS: The mean ABO-OGS score was satisfactory and did not differ by Angle classifications. The indices making substantial contributions to ABO-OGS were occlusal contacts, occlusal relationships, overjet, and alignment. Disocclusion time in post-orthodontic patients was longer than normal. Occlusion time, disocclusion time, and force distribution during dynamic motions were considerably influenced by static ABO-OGS measurements, especially occlusal contacts, buccolingual inclination, and alignment. CONCLUSION: Post-orthodontic cases that passed the static evaluation of clinicians and ABO-OGS may nevertheless be left with dental casts interference in dynamic motions. Both static and dynamic occlusion should be extensively evaluated before ending orthodontic treatment. Further research is needed on dynamic occlusal guidelines and standards.

Comparison of Occlusal Digital Analysis Using T-Scan in Orthognathic Surgery with Only Conventional Orthodontic Patients.

Aim and Objectives: The aims of this study were to compare the changes in occlusal parameters, TMJ status clinically in patients after the completion of orthognathic surgery, and patients undergoing only orthodontic treatment and with patients having normal occlusion, using T-Scan. Methodology: This prospective controlled clinical trial, consisting of three groups with a sample size of twelve. Group 1 consisted of patients who underwent orthognathic surgery and orthodontic treatment. Group 2 consists of patients who underwent only orthodontic treatment (camouflage). Clinical examination of the patient (TMJ and Occlusal status) and T-Scan was performed at the time of debonding of the orthodontic brackets, 6 months and 1-year after first evaluation for group 1 and 2 patients. Results: The collected data between groups are compared and interpreted. The statistical analysis was performed using STATA/IC version 16.1 statistical software. Intragroup comparison for the study variables occlusion time, disocclusion time and maximum bite force between different time periods (T1, T2, T3) for all the three intervention groups using repeated measures. Hypothesis testing for maximum bite force, occlusion time and disocclusion time in orthognathic group (Group 1) as compared to orthodontic group (Group 2) for three different time periods using repeated measures ANOVA and Bonferroni test showed P value < 0.05 which is statistically significant. Conclusion: In conclusion, evaluation of occlusion using T-Scan give us an insight of the discrepancies in occlusion which is useful during pre-operative planning and especially in the post-operative follow-up period during the retention phase. Examination of TMJ in these patients at various intervals is necessary as any minor occlusal disturbances may lead to TMJ disorders.

Application in the analysis of the occlusal force of free-end missing tooth implant restoration with T-SCAN III.

Introduction: The occlusal force of the teeth in the dental arch and the remaining adjacent natural teeth will change after implant restoration with a free-end missing tooth. This study intends to use the T-SCAN III scanner to collect dynamic quantitative data before and after the restoration of free-end implants and to explore the application of the T-SCAN III in redistributing the occlusal force of free-end implants. Methods: In this study, 24 patients with free-end implant restoration were selected, and their occlusion was tested before, immediately after, and 3 months after implant restoration. Results: In all 24 cases, the bite force of the first natural tooth adjacent to the implanted tooth after restoration changed from 19.12% ± 9.48%-12.93% ± 11.47% (p < 0.01). For additional data analysis, all cases were further subdivided by single implant and fixed bridge restorations. In 17 cases, there was a successful follow-up after 3 months. The percentage of the total bite force of dental arch with implant increased from 41.92% ± 10.78%-53.06% ± 10.71% (p < 0.01). Discussion: This study shows that the free-end implant restoration protects the remaining natural teeth, and the patient's missing dental arch bite force improves within 3 months of implant restoration.

Aspects of Dental Occlusion Assessed with the T-Scan System among a Group of Romanian Dental Students in a Cross-Sectional Study.

This study evaluated the occlusal relationships in students with bruxism, using the T-Scan III system, and their correlation with the activity of the masticatory muscles assessed through surface electromyography (sEMG). The study group was divided into two subgroups (based on self-reporting): 20 participants with possible bruxism and 20 participants without possible bruxism; all participants underwent the following evaluations: sEMG recordings using the dia-BRUXO device for masticatory muscles assessment, as well as static and dynamic occlusion using the T-SCAN III system. The analysis of the maximum intercuspidal (MI) position revealed a positive moderate association between the values of the occlusal forces in MI distributed along the two hemiarches, and the number of grinding events during daytime, which was statistically significant (p < 0.05). The analysis of protrusion movements reflected statistically significant differences between the non-working interferences and sEMG parameters specific to bruxism (p < 0.05). The analysis of laterotrusion movements indicated that participants with anterolateral guidance presented higher values of awake bruxism indexes and higher values of clenching events during nighttime. For all three mandibular movements, their duration was higher for the study group compared to the control group. Therefore, this study confirmed the utility of sEMG recordings in the bruxism diagnosis process, as well as the association between dental occlusion and bruxism.

Evaluation of the accuracy of T-scan system and Cerec Omnicam system used in occlusal contact assessment.

Purpose: The objective of the present study was to determine the accuracy of T-scan system and Cerec Omnicam system with respect to the evaluation of occlusal contact by quantitatively comparing the occlusal contact areas and the overlapping ratios of occlusal contact areas obtained from these systems. Material and methods: The occlusal contact of 20 adolescents with normal occlusion was measured with the T-scan system and the Cerec Omnicam system, respectively. The occlusal contact areas in the intercuspal position were then quantified with Adobe Photoshop CS6 Software. The same procedure was repeated for each subject using with 8 µm articulating paper as the control group. The overlapping ratio of T-scan system and Cerec Omnicam system was calculated respectively, which is defined as the ratio of overlapping areas comparing with those obtained from articulating paper. To examine the accuracy of T-scan system and Cerec Omnicam system, the Paired t-test was applied. The reproducibility of T-scan system was evaluated with Wilcoxon matched-pairs signed-ranks test by comparing the occlusal contact areas between two repeated measurements. In all statistical analysis, the level of significance was set to α = 0.05. Results: Results demonstrated measured occlusal contact areas were significantly different between those obtained between T-scan system and Cerec Omnicam system (P < 0.05). The tooth position of two-dimensional virtual dental arch established by T-scan system based on the width of the central incisor was in disagreement with the actual tooth position. The overlapping ratios obtained from Cerec Omnicam system were higher than those obtained from the T-Scan system (P < 0.05). The sensitivity of T-Scan system in anterior teeth area decreased when sensors are used more than once (P < 0.05). Conclusions: In the intercuspal position, the accuracy of Cerec Omnicam system for occlusal contact assessment is higher than that of T-scan system. The T-scan system demonstrates good reproducibility in the premolar region and the molar region, but poor reproducibility in the anterior teeth region. Clinical implications: In the intercuspal position, Cerec Omnicam system is more accurate than T-scan system, which can quantitatively analyze occlusal relationship in terms of number, position, size and distribution of occlusal contact points. When evaluating occlusal contacts, the accuracy of T-scan system in anterior teeth region is significantly lower than that of premolar and molar regions.

Comparison of occlusal bite force distribution in subjects with different occlusal characteristics.

OBJECTIVE: To analyze bite force distribution in subjects with different occlusal characteristics. METHODS: This prospective study included 132 candidates (50 males, 82 females) seeking orthodontic treatment, who were divided into four groups based on Angle's classification of malocclusion. T-Scan® III Version 7.0 was used to record their relative distribution of bite forces, which were compared using gender, Angle's occlusal classification, overjet, overbite, space analysis, sagittal, and transverse skeletal relations variables. RESULTS: ANOVA revealed significant differences in posterior/anterior bite force ratios between sagittal dental and skeletal relationships, overjet, and overbite groups (p < 0.05). No significant difference was found between different space analysis and transverse relationship groups (p > 0.05) or between genders (p > 0.05). CONCLUSION: Subjects with Class III, decreased overjet and decreased overbite displayed higher bite force in posterior teeth compared to other groups. This feature must be considered when evaluating patients with dental and periodontal pathologies that might be affected by excessive tooth stress, especially in subjects with oral parafunctions and bruxism.

Clinical Study on the Occlusal Change of Skeletal Class Ⅰ Malocclusion Treated with Invisible Appliance and Fixed Appliance / 昆明医科大学学报

Objective To compare the clinical efficacy of invisible appliance and fixed appliance in the treatment of skeletal class I malocclusion.Methods A prospective cohort study with a minimum sample size of no less than 19 subjects in each group was used,and 46 adult patients with bone type I were eventually enrolled.According to the type of appliance,they were divided into the invisible appliance group(group A)with 25 patients and the fixed appliance group(group B)with 21 patients.Data were analyzed before orthodontic treatment(T0)after(T1)between invisible and traditional fixed orthodontics.Results The static occlusion index and PAR score were improved after treatment,and the differences were statistically significant(P<0.01).The occlusal dynamic parameters including OT,OFAT,OFPT,AOF and DT were significantly improved after treatment(P<0.01).There were significant differences in AOF,forward and lateral DT between the two groups(P<0.01),the invisible group was better than the fixed group.Conclusion Both the dynamic and static occlusal changes can be greatly improved with invisible and fixed appliance in the treatment of patients with class I malocclusion.Invisible appliance is better than fixed appliance in balancing occlusion,eliminating and reducing occlusal interference.

A comparative study of conventional and Hall techniques of crown placement using finite element stress analysis.

Background: Hall technique of crown placement causes the changes in vertical occlusal dimension; the mode of settlement of which needs to be explored. Aim: To assess and compare the changing patterns of stress distribution following placement of stainless steel crowns on primary teeth by Hall and conventional techniques using a finite element model analysis. Materials and Methods: The clinical crown heights of primary molars restored with Hall and conventional techniques and opposing teeth in contact, vertical dimension changes in the primary canine area were measured using intraoral digital scan. T-scan was used to measure the changes in bite force while the finite element analysis was used to assess deformative changes on the 2nd, 5th, 10th, and 15th days. Results: The Hall technique of crown placement caused more stress distribution in the tooth supporting tissues that settled in 2 weeks as compared with conventional technique of crown placement in which settlement occurred in 2 days. Conclusion: The settling of vertical occlusal dimension as well as stress distribution in Hall technique probably takes place by intrusion of crowned tooth and opposing teeth in contact.