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.

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.

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.

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.

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.

Comparison of two different digital occlusal analysis methods

OBJECTIVES

The aim of this study is to compare the sensitivity of T-Scan digital occlusal analysis system and the occlusal analysis mode of the CEREC Omnicam system, which is mainly used for design/production, using the data recorded at the maximum intercuspal position.

MATERIALS AND METHODS

Occlusal recordings were obtained from healthy 20 females and 20 males aged 18-25 at the maximum intercuspal position. Records were saved as.jpeg format and transferred to Adobe Photoshop CS6 program. Blue, green, and red colors (shown by the same color codes in both systems) representing light, intense, and tight contacts, respectively, were evaluated in terms of the pixel counts. For statistical comparison, the differences between the systems independent sample T test and, between the genders, one sample T test were used (α = 0.05).

RESULTS

The total numbers of pixels of all colors which are evaluated with T-Scan and CEREC Omnicam in females were 31,296.6 and 15,745, respectively, and in males 39,812.3 and 17,462, respectively. In both systems, the blue contact area is the most seen. For all colors tested, T-Scan recorded more contact than those of CEREC Omnicam in both genders and statistically significant difference was found between two systems for all colors. In both systems, recorded contacts are significantly higher in men than in women. Compared with women, 27% more contact area was recorded in men with T-Scan and 11% more with CEREC Omnicam was obtained.

CONCLUSIONS

While T-Scan was found sensitive even in the diagnosis of light contacts, the CEREC Omnicam was found sensitive only in the diagnosis of tight contacts.

CLINICAL RELEVANCE

Although both T-Scan and CEREC Omnicam are effective in occlusal analysis, T-Scan's sensitivity was found to be higher.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04798729.

Accuracy, Reliability and Clinical Implications of Static Compared to Quantifiable Occlusal Indicators

OBJECTIVE

This literature review summarizes the properties, advantages, limitations, and clinical implications of employing static occlusal indicators compared to quantifiable digital occlusal indicators during occlusal adjustments.

METHOD

An electronic database search of dental literature was carried out in PubMed/MEDLINE using the key words Occlusal Indicators, Occlusal Assessment, Static, Reliability, Dynamic, Repeatability, Validity and Clinical Accuracy. A total of 231 papers were isolated, with 129 papers considered for review.

RESULTS

The included papers were grouped by Static and Dynamic Occlusal indicators. The numbers of papers in the Static Group was extremely low (only 20 papers) compared to The Dynamic group (T-Scan: 89; Dental Prescale: 28; Intraoral Scanners:17).

CONCLUSION

Little evidence supports the use of static occlusal indicators due to their high degree of subjectivity required during implementation. However, much scientific evidence supports the use of T-Scan, as it measures relative occlusal forces and timing objectively, accurately, and repeatedly. For the improvement of Occlusal Practice, Subjective Interpretation using Static occlusal indicators should be replaced with digital ones for objective measurements.

CLINICAL RELEVANCE

The computerized occlusal analysis system is well studied and has the capacity to provide precise time and force sequencing information to objectively evaluate occlusal contacts for improved treatment outcome.

Clinical analysis of CAD-CAM milled and printed complete dentures using computerized occlusal force analyser

BACKGROUND

Digital complete dentures (CDs) by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques (milling and three-dimensional (3-D) printing) have been evaluated clinically and provided satisfactory results. But clinical studies assessing occlusal forces by digital dentures are lacking.

OBJECTIVES

To compare the occlusal force parameters in complete dentures (CDs) fabricated by milling, 3-D printing and conventional techniques having 3 commonly used occlusal schemes, using computerized occlusal force analysis system (Tech-Scan III- T-Scan III).

METHODS

A total of 45 CDs were fabricated for 5 patients. Nine sets of CDs were made for each patient and were divided into 3 groups: Conventional CDs (CCD), Milled CDs (MCD), and 3-D printed CDs (3-DP CD). The CDs in each group were further divided into 3 sub-groups based on occlusion schemes - bilateral balanced (BBO), lingualized (LO) and mono plane (MP). Occlusal force analysis [percentage (%) of occlusal force applied on the right and left sides of the arch difference between them, centralization of forces and % of maximum occlusal/bite force] was done using computerized occlusal analysis system (T-Scan III) at the time of denture insertion. Univariate regression analysis and logistic regression analysis were performed (p< 0.05).

RESULTS

The intergroup comparison of force distribution on right and left side in CDs fabricated by various techniques showed insignificant differences (p> 0.05) but statistically significant differences (p< 0.01) were found in right-left side force difference, maximum bite force % and centralization of forces. The maximum force difference on right and left side was observed CCD with MO (37.48 ± 1.03 N) and maximum occlusal-bite force % was observed for 3-DPCD with LO (95.40 ± 1.30 N). In comparison to 3-DP CD, the chances of centre of force out of ellipse (centralization of forces) was 3.36 and 2.15 times more in CCD and MCD techniques made CDs respectively.

CONCLUSIONS

The occlusal parameters in CDs were affected by the fabrication techniques and occlusal schemes of CDs. The digital CDs retain adjusted occlusal schemes better and 3-DP CDs with BBO and LO occlusal schemes provided centralization of forces, better distribution and high maximum occlusal force % respectively.

Computerized occlusal forces analysis in complete dentures fabricated by additive and subtractive techniques

BACKGROUND

Fabrication of complete dentures by computer-aided designing and computer-aided manufacturing (CAD-CAM) techniques are now common. Subtractive and Additive are the two principal CAD-CAM techniques used for this purpose. However, studies that evaluated the occlusal forces by CDs manufactured by these techniques are lacking.

OBJECTIVES

To compare the occlusal forces in complete dentures fabricated by additive, subtractive and conventional techniques with different occlusal schemes, using computerized occlusal force analysis system [Tech-Scan III (T-Scan III)].

METHODS

Three groups (Gr) were made on the basis of techniques of fabrication of CDs: Conventional CDs (CCD), Subtractive CDs (SCD), and Additive CDs (ACD). Each group CDs were further divided into three sub groups based on occlusion schemes: bilateral balanced occlusion (BBO), lingualized occlusion (LO) and mono plane occlusion (MO). A total of 45 CDs were made: 15 in each group with 5 CDs of each occlusal scheme. For all samples, occlusal force analysis (percentage of occlusal force applied on the right and left sides of the arch, centralization of forces and percentage of maximum occlusal force) was done using computerized occlusal analysis system: T-Scan III. Univariate regression analysis and logistic regression analysis were used to find the effects of the technique of fabrication and occlusion scheme over the occlusal forces (p< 0.05).

RESULTS

The intergroup comparison revealed statistically significant differences (p< 0.01) in right-left side force difference, maximum bite force in CDs fabricated by various techniques and with different occlusion schemes. Though the effect of occlusion scheme was more than the technique of fabrication (according to effect size estimation). The maximum force difference between right-left side was observed in combination of CCD technique and MO scheme (36.88 ± 2.82 N). Furthermore, the maximum bite force was observed for SCD technique (89.14 ± 6.08 N) and LO scheme (92.17 ± 3.22 N). In comparison to ACD, the chances of centre of force out of ellipse was 2.53 time more in CCS and 0.75 times less in SCD techniques and in comparison to MO, the chances of out of ellipse was 0.298 times less in BBO and 0.396 times less in LO schemes, though these chances were not statistically significant (p> 0.05).

CONCLUSIONS

The digital CDs fabricated by subtractive technique were proved to be superior to additive technique in terms of occlusal force analysis on tested parameters. However, further research is needed on patients to determine the exact superiority of one technique over the other.

Variation in dental occlusal schemes two years after placement of single-implant posterior crowns. A preliminary study

Some authors have recommended that implant-supported single crowns should only contact during heavy clenching. However, a lack of occlusal contact with moderate clenching may cause supra-eruption of antagonist natural teeth. The main objective of this study was to assess changes in the occlusal contacts of posterior implant-supported single crowns with natural antagonist teeth two years after placement. The occlusal schemes of 14 patients who received 16 implant-supported single crowns in molar and premolar regions were assessed in this prospective study. Just after crown placement, at 6 months and after 2 years a silicone maxillomandibular relationship and T-scan records were obtained during the intercuspal position with light and heavy clenching, determined using near half of the maximum force and maximum force respectively. Occlusal contacts were assessed quantitatively and qualitatively in the implant-supported single crowns, contralateral tooth and adjacent tooth; the latter two were used as controls. After six months and two years, no significant variations were observed in any region of the occlusal scheme in any assessments, including silicone record or T-Scan, using light or heavy clenching, and qualitative or quantitative occlusal contact assessment. In this preliminary study, the occlusal scheme did not vary at the intercuspal position two years after placing posterior implant-supported single crowns.

Unbiased Screens Show CD8+ T Cells of COVID-19 Patients Recognize Shared Epitopes in SARS-CoV-2 that Largely Reside outside the Spike Protein

Developing effective strategies to prevent or treat coronavirus disease 2019 (COVID-19) requires understanding the natural immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We used an unbiased, genome-wide screening technology to determine the precise peptide sequences in SARS-CoV-2 that are recognized by the memory CD8+ T cells of COVID-19 patients. In total, we identified 3-8 epitopes for each of the 6 most prevalent human leukocyte antigen (HLA) types. These epitopes were broadly shared across patients and located in regions of the virus that are not subject to mutational variation. Notably, only 3 of the 29 shared epitopes were located in the spike protein, whereas most epitopes were located in ORF1ab or the nucleocapsid protein. We also found that CD8+ T cells generally do not cross-react with epitopes in the four seasonal coronaviruses that cause the common cold. Overall, these findings can inform development of next-generation vaccines that better recapitulate natural CD8+ T cell immunity to SARS-CoV-2.

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.

Effect of condylar osteochondroma resection through an intraoral approach on the masticatory functions: a preliminary evaluation based on occlusion and temporomandibular joint functions

With this research, we aimed to evaluate the effect of condylar osteochondroma (OC) resection through an intraoral approach on the masticatory functions. Resection of condylar OC was carried out via an intraoral approach with the help of three-dimensional (3D) design, endoscope, and navigation system. The T-Scan III computerised occlusal analysis system was used to evaluate the occlusal force distribution, recorded at pre-treatment (T1) and post-treatment (T2) intervals. Records of the clinical examination of the temporomandibular joint (TMJ), including maximal interincisal opening, mandibular lateral and forward movements, were also collected. Ten patients with condylar OC were enrolled in this study. The difference of force distribution between bilateral occlusion was reduced in T2 compared with T1 (11.92% ± 4.41% vs 48.52 % ± 28.37%, p<0.05), indicating better occlusal force distribution obtained after surgery. There was no significant difference in functions of the TMJ, such as maximal interincisal opening, and mandibular lateral and forward movements between T2 and T1 (p>0.05). Accordingly, condylar OC resection through an intraoral approach would obtain a satisfactory occlusal balance with no impairment of the temporomandibular joint functions.

Bite Force and Occlusal Patterns in the Mixed Dentition of Children with Down Syndrome

PURPOSE

Oral function in Down Syndrome (DS) patients has been of interest to clinicians and researchers. This study aimed to evaluate the parameters of occlusal force and pattern of children with Down syndrome (DS) during mixed dentition when compared to age and gender-matched controls.

MATERIALS AND METHODS

Thirty DS and 30 healthy children, aged 7 to 12 years, participated in the evaluation of the parameters of the occlusal pattern and occlusal force distribution analysis. Both groups underwent clinical examination, occlusal force and pattern measurements using a computerized occlusal analysis system (T-Scan 8 occlusal analysis, Tekscan, Inc., S. Boston, MA). Occlusion time, percentage of force distribution, force outliers, center of force target area, center of force trajectory and evaluation of closure arc were compared between the two groups using the Pearson's Chi Square test.

RESULTS

Children with DS had more occlusal and vertical malocclusion compared to the control group (p < 0.001). The occlusion time for DS group (0.75 ± 0.7s) was significantly longer than the control group (0.015 ± 0.05s) (p < 0.001). The closure arc for DS group was mostly irregular (53%), while the control group showed ideal closure arc. In control group, the age had a significant influence on the occlusion time, while height, weight, and BMI had a significant influence on the mouth opening. None of these variables had such effect on children with DS.

CONCLUSIONS

The results of this study showed high prevalence of orofacial dysfunction among DS population. The occlusal analysis showed that children with DS had longer occlusion time and a lack of ideal occlusion pattern compared to age matched controls.

Computerised occlusal analysis of mini-dental implant-retained mandibular overdentures: A 1-year prospective clinical study

Occlusal analysis is a substantial tool for the functional improvement evaluation after using implant-retained overdenture comparing to complete denture without dental implant retaining. To evaluate occlusal pattern, chewing force distribution in mini-dental implant-retained mandibular overdentures by computerised occlusal analysis system and to compare patient satisfaction after 1-year function. Thirty-one patients wearing complete dentures were included in the study. Prior to mini-dental implant-retained treatment, all patients were assessed for occlusion and force distribution using computerised occlusal analysis system (T-Scan^® ), and then, all patients received two mini-dental implant-retained mandibular overdentures. Mini-dental implants were immediately loaded using low vertical profile attachments (Equator^® ). T-Scan^® was used to evaluate chewing force and force distribution at 1 day, 3 months, 6 months and 12 months. The patient satisfactions before implant placement and after 1 year were evaluated using questionnaires which included satisfaction of denture quality, psychosocial behaviour and chewing efficiency modified from the validated questionnaires. Clinical evaluation of two mini-dental implant-retained mandibular overdentures showed 100% success rate after 1 year. T-Scan^® demonstrated that maximum occlusal contact force increased continuously. The force distribution; the tooth contact number increased over the period. At 1-year follow-up, overall patient satisfaction was significantly greater than before receiving mini-dental implant treatment (P < .001). Using computerised occlusal analysis, mini-dental implants improve complete denture function significantly in terms of maximum occlusal contact force, tooth contact number without the impairment of force distribution. The oral function of the patients has been enhanced.

Occlusion in the digital era: a report on 3 cases

In the following case studies we wish to discuss the necessity of making use of digital technology in the occlusion-oriented dental practice. In the three presented cases, patients underwent complex orthodontic, implant and prosthetic treatment, the aim being to re-establish the functionality of the dento-maxillary apparatus. The patients were evaluated clinically at the completion of the treatment. Subsequently, during the follow-ups (which varied between 2 and 4 years), clinical analysis using articulating paper was carried out and possible signs of relapse were specifically searched for. Occlusal clinical analysis was later on compared with the occlusion recorded using the TRIOS® 3 intraoral scanner (3Shape) and the T-Scan™ Novus™ device (TekScan). Clinical and digitally obtained scanner results were similar. The results yielded by the T-Scan™ Novus™ device were different and they were also relevant for elucidating the cause of the symptomatology.

Clinical investigations of the comparability of different methods used to display occlusal contact points

AIM

The aim of the present study was to evaluate the number, strength, and position of occlusal contacts shown using an intraoral scanner (IOS) and a digital occlusal analysis system (T-Scan) compared with the current gold standard using occlusal foil (OF).

MATERIALS AND METHODS

Occlusal contacts were analyzed for 70 volunteers using OF in maximum intercuspation (MI). The contact points obtained using the IOS were evaluated using a screenshot from Zirkonzahn.Modellier CAD software. Finally, the volunteers were asked to bite on the sensor sheet of the T-Scan system. For the evaluation of these data, the contact points of the OF and the IOS were graded as light, medium, and strong. Furthermore, the positions of the contact points were analyzed for the anterior region (premolars and molars). Parametric statistical tests were applied to analyze the differences among the three methods.

RESULTS

The mean number of all contact points was similar: 29 ± 8 with the OF, 30 ± 12 with the IOS, and 24 ± 10 with the T-Scan. However, results were different in terms of the grading of the strength of contact points: mean number of light contacts: 8 ± 4 OF vs 17 ± 8 IOS and 17 ± 6 T-Scan; medium contacts: 12 ± 5 OF vs 8 ± 4 IOS and 5 ± 4 T-Scan; and strong contacts: 9 ± 5 OF vs 6 ± 6 IOS and 4 ± 2 T-Scan. The positions of the occlusal contact points were also different.

CONCLUSION

The data sets showed that there were differences in the distribution of occlusal contact points evaluated using the OF, the IOS, and the T-Scan system. Although the number of detected occlusal contacts was similar, different occlusal contact protocols were determined by the three different methods.

Modifications in Class I and Class II Div. 1 malocclusion during orthodontic treatment and their association with TMD problems

Objective: To observe changes in tooth movements of patients with Class I and Class II malocclusion during the first 6 months of orthodontic treatment and to investigate the relation between TMJ problems and these changes. Methods: The sample was comprised of 63 individuals (20 control, 25 Class I malocclusion, 18 Class II Div. 1 malocclusion). Occlusion analysis was performed through T-Scan® record and chewing pattern examination before and after the 6-month period. The existence of TMD was evaluated using joint vibration analysis (JVA). Patients with malocclusion had active fixed orthodontic treatment. Results: Disclusion time reduced in the patients group during the treatment period. No association was observed between the first 6-month period of the orthodontic treatment and TMD. Discussion: It is suggested that occlusion analyses should be done before any orthodontic treatment, and disclusion time should be minimized as much as possible.

The combined effects of salivas and occlusal indicators on occlusal contact forces

BACKGROUND

Some occlusal detection products are designed for use on dry teeth, but this is not always achieved. Others are suited for dry and wet applications.

OBJECTIVE

The objective of this study is to assess the combined effects, on occlusal contact forces, of two previously studied affecting variables-occlusal detection products and saliva.

METHODS

We used a full-arch dentiform with three occlusal detection products (an articulating film, an articulation paper and T-Scan) in combination with human (HS) and an artificial saliva. The maxillary arch assembly, weighing ~54 N (the maximum bite force), was lowered onto (occlusion) and lifted off (disclusion) of the mandibular arch through 10 cycles by a mechanical testing machine. The forces and moments acting on the mandibular arch were continuously recorded by a load cell that supported it.

RESULTS

The maximum values of F_lateral (the in-occlusal plane component of the occlusal contact force) were analysed by occlusion/disclusion separately using one-way ANOVA, with factor for group type to identify the significant effect of salivas on products, effect of products, effect of salivas with products, effect of human saliva. A difference in occlusion and/or in disclusion was considered different. Statistical differences (P < 0.0001) in F_lateral were found in: dry product vs product + HS, dry product vs product + artificial saliva (with articulating film and T-Scan) and HS vs product + HS (with articulation paper and T-Scan).

CONCLUSION

All products were affected by the salivas, except articulation paper by artificial saliva.

A digital poll of dentists testing the accuracy of paper mark subjective interpretation

AIMS

The aim of this study was to test subjective interpretation accuracy via digital polling of a large group of dentists to determine whether dentists can reliably interpret occlusal forces by visually assessing articulating paper markings.

METHODS

One hundred fifty-two dentists selected the most forceful occlusal contact in five occlusal-view photographs of articulating paper marks that were compared against T-Scan® relative occlusal levels of the same tooth contacts.

RESULTS

The mean correct response was a mere 13.13% correct (86.87% incorrect). Random chance was calculated at 16.7% correct. The cuspid contacts were the least often chosen as the most forceful contact. The Mann-Whitney U test found a significant difference between choosing the anterior teeth vs. posterior teeth. onclusions: Subjective interpretation is an inaccurate method for determining high force occlusal contacts. The reported low correct percentage fell below random chance, suggesting that dentists are unable to detect high occlusal force from looking at articulating paper marks.

Does the presence of an occlusal indicator product affect the contact forces between full dentitions?

Studies have explored occlusal marking interpretation, repeatability and accuracy. But, when an occlusion detection product is interposed between teeth, direct tooth-tooth occlusal contact relationships are replaced by tooth-material-tooth structures. Thus, the marks cannot reflect the original contacts. This has been shown for single tooth pair contacts. The purpose of this laboratory study was to similarly examine full dentitions. A dentiform was set into Class I centric occlusion with the mandible supported by a load cell. The maxillary arch was guided by precision slides. As the weighted (~52 N) upper assembly was lowered onto and raised off the mandibular arch, the loads on the mandible were measured. With and without (control) occlusal marking material, the steps were as follows: (cleaning - control 1 - material 1) … (cleaning - control 6 - material 6). The six materials were as follows: Accufilm I and II, Rudischhauser Thick and Thin, Hanel Articulating Silk and T-Scan. Then, the six sets of (cleaning - control - material) measurements were repeated with the mandibular assembly shifted, in turn, by 0·1 mm in the Anterior, Posterior, Right and Left directions. The five (Centric and four 0·1 mm shifted) occlusal relationships produced grossly different tooth-tooth (control) load profiles. And, in general, these controls were affected, in different ways, by the marking products. Among the five conventional products, the Rudischhausers fared the worst and the electronic T-Scan was an extreme outlier. Thus, in general, popular occlusal detection products alter the occlusal contact forces, and therefore, their markings cannot characterise the actual occlusion.

Average chewing pattern improvements following Disclusion Time reduction

OBJECTIVES

Studies involving electrognathographic (EGN) recordings of chewing improvements obtained following occlusal adjustment therapy are rare, as most studies lack 'chewing' within the research. The objectives of this study were to determine if reducing long Disclusion Time to short Disclusion Time with the immediate complete anterior guidance development (ICAGD) coronoplasty in symptomatic subjects altered their average chewing pattern (ACP) and their muscle function.

METHODS

Twenty-nine muscularly symptomatic subjects underwent simultaneous EMG and EGN recordings of right and left gum chewing, before and after the ICAGD coronoplasty. Statistical differences in the mean Disclusion Time, the mean muscle contraction cycle, and the mean ACP resultant from ICAGD underwent the Student's paired t-test (α = 0.05).

RESULTS

Disclusion Time reductions from ICAGD were significant (2.11-0.45 s. p = 0.0000). Post-ICAGD muscle changes were significant in the mean area (p = 0.000001), the peak amplitude (p = 0.00005), the time to peak contraction (p < 0.000004), the time to 50% peak contraction (p < 0.00001), and in the decreased number of silent periods per side (right p < 0.0000002; left p < 0.0000006). Post-ICAGD ACP changes were also significant; the terminal chewing position became closer to centric occlusion (p < 0.002), the maximum and average chewing velocities increased (p < 0.002; p < 0.00005), the opening and closing times, the cycle time, and the occlusal contact time all decreased (p < 0.004-0.0001).

CONCLUSION

The average chewing pattern (ACP) shape, speed, consistency, muscular coordination, and vertical opening improvements can be significantly improved in muscularly dysfunctional TMD patients within one week's time of undergoing the ICAGD enameloplasty. Computer-measured and guided occlusal adjustments quickly and physiologically improved chewing, without requiring the patients to wear pre- or post-treatment appliances.

The effect of various occlusal reduction levels on postoperative pain in teeth with symptomatic apical periodontitis using computerized analysis: a prospective, randomized, double-blind study

OBJECTIVE

The objective of this study was to evaluate the effect of various occlusal reduction levels on the postoperative pain in teeth diagnosed as symptomatic apical periodontitis by using a computerized analysis system.

MATERIALS AND METHODS

Thirty-nine molar teeth with symptomatic apical periodontitis were included. After the root canal preparation and filling was performed, the subjects were divided into three groups according to the level of occlusal reduction determined by using T-Scan (T-Scan III for Windows, Tekscan Inc., South Boston, MA) as follows: (1) no reduction (control), (2) semi-reduction, and (3) full-reduction groups. Preoperative and postoperative pain levels using visual analogue scale, percussion pain, and analgesic intake were recorded for each subject. The data were evaluated statistically using two-way analysis of variance and Holm-Sidak post hoc tests at a 95 % confidence level (P = 0.05).

RESULTS

There was no significant difference between the groups in terms of occlusal reduction (P > 0.005).

CONCLUSION

Within the limitation of the present study, there were no significant differences among the no reduction, semi-reduction, and full-reduction groups at 1, 3, 5, and 7 days in terms of postoperative pain levels.

CLINICAL RELEVANCE

Occlusal reduction, determined using a computerized analysis system, did not influence the postoperative pain in teeth diagnosed as symptomatic apical periodontitis.

Computerized occlusal analysis: correlation with occlusal indexes to assess the outcome of orthodontic treatment or the severity of malocculusion

Objective

The aims of our study were to verify the validity of the T-Scan III system (Tekscan) as an objective occlusal evaluation tool, and to assess the differences between two occlusal indexes-the peer assessment rating (PAR) index and the American Board of Orthodontics objective grading system (OGS)-by comparing the scores derived from the T-Scan III system with the two occlusal indexes and analyzing the correlations between them.

Methods

The final study sample included 48 adult volunteers (39 men and 9 women, mean age 24.14 ± 3.16 years), after excluding 29 volunteers whose occlusion could not be evaluated by the T-Scan III system due to severe skeletal or occlusal problems. PAR index and OGS scores were assessed using dental study models, and measurements of centric occlusion, protrusive movement, and lateral excursion movement were obtained via the T-Scan III system. The results were analyzed to determine correlations.

Results

Occlusal analysis by the T-Scan III system was clinically reliable (p < 0.05), and the PAR index and OGS scores were significantly correlated with several measurements obtained with the T-Scan III system (p < 0.05).

Conclusions

The T-Scan III system is a quantitative and reliable method for occlusal evaluation, and represents a potential substitute for occlusal indexes. Compared to the PAR index, the OGS scores of more variables were significantly correlated with the T-Scan measurements.

Computerized analysis of occlusal contacts in bruxism patients treated with occlusal splint therapy

PURPOSE

Occlusal splints are commonly used to prevent tooth wear caused by bruxism. However, the effects of splints on occlusion are still unclear. Although it is rarely alluded in literature, splints can provoke severe occlusal alterations and other complications. This study was aimed to identify differences in the responses of individuals with bruxism and healthy individuals to a full-arch maxillary stabilization splint in terms of occlusal changes.

MATERIALS AND METHODS

Occlusal contacts in 20 (5 male, 15 female) bruxism patients and 20 (5 male, 15 female) controls with normal occlusion were evaluated before and after occlusal splint therapy. T-Scan III, a computerized occlusal analysis system, was used to simultaneously measure occlusion and disclusion times as well as left-right and anterior-posterior contact distributions before splint therapy and 3 months after therapy. Wilcoxon and Mann-Whitney U tests were used for statistical analyses (α=.05).

RESULTS

No differences were found in the posterior contact of bruxism patients before and after stabilization splint treatment. However, differences in posterior contact were observed between bruxists and normal individuals prior to treatment, and this difference disappeared following treatment.

CONCLUSION

The results of this study showed the use of a stabilization splint may not have an effect on occlusion. However, the area of posterior occlusal contact among bruxists was found to be greater than that of normal individuals. According to this study, the clinical use of splints may be harmless.