Computerized occlusal analysis as an alternative occlusal indicator

Background: All disciplines of dentistry require that clinicians assess the articulation of the teeth/prosthesis with respect to simultaneous contacts, bite force and timing.

Aims: This article intends to describe the advantages and limitations of the data acquired when using a computerized occlusal analysis as a dynamic occlusal indicator.

Methodology: A search of the literature was completed (Medline, PubMed) using the keywords occlusion, occlusal registration, computerized occlusal analysis and T-Scan for dental.

Results: According to the evidence available, the computerized occlusal analysis system is the only occlusal indicator that demonstrates the ability to provide quantifiable force and time variance in a real-time window from the initial tooth contact into maximum intercuspation.

Conclusion: The reported advantages to accurately indicate occlusal contacts make the computerized occlusal analysis system a better occlusal indicator when compared with other non-digital convention indicator materials available.     

Status of occlusal contact during sleep bruxism in patients who visited dental clinics – A study using a Bruxchecker®

Objective: Bruxism-induced mechanical load causes various dental problems, and its treatment is challenging. The present study analyzed upper and lower tooth contacts to determine actual occlusal contact during sleep bruxism.

Methods: Tooth contact patterns were analyzed in 49 patients attending dental clinics, using a Bruxchecker®, cephalograms, and condylographs.

Results: Approximately 80% of individuals demonstrated contact from the anterior teeth to the molar region (ICPM); about 96% had mediotrusive grinding and contact. The tooth contact area increased with the flatness of the anterior occlusal plane. The ratio of the contact area of the anterior teeth to the overall tooth contact area increased with overbite. Bilateral ICPM and mediotrusive contact patterns were associated with a high frequency of temporomandibular disorder symptoms, clicking, and/or pain.

Discussion: The tooth contact area, anterior occlusal plane, and overbite are closely related, suggesting that tooth contact with the anterior teeth should be controlled with occlusal therapy.     

Relationship between craniocervical orientation and center of force of occlusion in adults

Objective: Clinical observation and anecdotal reports suggest changes can occur to dental occlusion following intervention with the National Upper Cervical Chiropractic Association (NUCCA) procedure. This case controlled study discerned if occlusion changes are measurable using a dental force plate (T-Scan®) following an adjustment to the craniocervical junction (CCJ).

Methods: A degree of case control was established by active patients being assessed twice prior to and following intervention. Before–after intervention assessment included posture evaluation and dental occlusion (T-Scan®).

Results: Findings suggest that changes in posture and occlusion can be observed after the NUCCA chiropractic procedure. Not all patients demonstrated a more balanced contact pattern following the adjustment, indicating a need for further investigation.

Discussion: These findings may suggest interconnectivity between the CCJ and an individual’s occlusal contacts and support the need for further integration between chiropractors and dentists seeking to co-manage temporomandibular joint disorders.     

Clinician accuracy when subjectively interpreting articulating paper markings

Aims:

The aim of this study was to determine whether Subjective Interpretation of paper markings is a reliable method for identifying the relative occlusal force content of tooth contacts.

Methodology:

295 clinicians selected the “Most Forceful” and “Least Forceful” occlusal contacts in six occlusal-view photographs of articulating paper marks that were later compared against computerized occlusal analysis relative occlusal force measurements of the same tooth contacts. Means and standard deviations were calculated by years in clinical practice and by number of occlusion courses taken. A Chi-square analysis was also performed.

Results:

The mean correct for 295 participant dentists was 1·53 (±1·234). There were no significant differences found for years in practice (P>0·16) or number of occlusion courses taken (P>0·75). The Chi-square analysis showed a sensitivity of 12·6%, a specificity of 12·4%, a positive predictive value of 12·58%, and a negative predictive value of 12·42%. Chance was calculated at 12·5% correct.

Conclusions:

Subjective Interpretation is an ineffective clinical method for determining the relative occlusal force content of tooth contacts. The reported low scores obtained from a large group of participant dentists suggest clinicians are unable to reliably differentiate high and low occlusal force from looking at articulating paper marks. This longstanding method of visually observing articulating paper marks for occlusal contact force content should be replaced with a measurement-based, objective method.     

Phantom bite: a case report and literature review

Objective:

Phantom bite is a rare and challenging condition that dentists may encounter in their daily clinical practice. Patients with phantom bite typically present with many failed repeated occlusal treatments, such as full-mouth prosthetic reconstructions and orthodontic treatments, to overcome their distressing symptoms.

Method and result:

A 55-year-old female with no history of medical problems presented with bite discomfort. She complained of discomfort from a “bite” and pressure-like feeling in her right upper three maxillary posterior teeth. Examination revealed no temporomandibular disorder (TMD) abnormalities. A thorough evaluation of her oral structures revealed no dental, periodontal, or mucosal pathologies.

Conclusion:

Owing to the great potential of conditions for financial loss and litigation problems, dentists, particularly those who perform bite-changing procedures, should be aware of this condition. This case is presented to highlight many of the clinical characteristics of phantom bite.     

The craniofacial morphology and maximum bite force in sleep bruxism patients with signs and symptoms of temporomandibular disorders

Objectives:

The purpose of the present study was to compare craniofacial morphology and bite force of bruxist patients with signs and symptoms of temporomandibular disorders.

Method:

Fourteen subjects with sleep bruxism and 14 healthy subjects participated. The signs and symptoms of the temporomandibular disorders were identified according to the Craniomandibular Index (CMI). Maximum bite force was measured using strain-gage transducers. Lateral cephalometric films were taken, and linear and angular measurements were performed.

Results:

Bite force between bruxist and non-bruxist females was not significant, whereas males with bruxism revealed higher bite forces. None of the linear and angular measurements differed significantly between bruxist and non-bruxist males. However, higher mandibular corpus length and anterior cranial base length, and lower gonial angle were observed in bruxist females compared to non-bruxist females. Negative correlation between bite force and CMI values was found in both genders.

Discussion:

Bruxist females had higher CMI values than bruxist males, which could lead to relatively lower bite forces.     

The role of occlusal factors on the occurrence of temporomandibular disorders

Aims:

The aim of this study was to investigate the relationship between occlusal factors and temporomandibular disorders (TMD).

Methodology:

One hundred patients were selected among those who sought medical or dental care in public practice in Recife, Brazil. The presence of malocclusions and absence of five or more posterior teeth were evaluated by the clinical exam. TMD diagnosis was given using Research Diagnostic Criteria (RDC/TMD). Statistics were carried out using Fisher and Mann–Whitney methods with 5% significance level, as well as multiple logistic regression analysis.

Results:

The sample was mainly comprised of women (83%), individuals over 30 years old (57%) and singles (53%). The percentage of TMD and malocclusion in total sample was 42% and 50%, respectively, while in TMD subjects, malocclusion was present in 38·1%. There was no association between TMD and the occlusal factors studied.

Conclusion:

It can be concluded that malocclusion and loss of five or more posterior teeth does not contribute to TMD.     

Comparison of closure occlusal force parameters in post-orthodontic and non-orthodontic subjects using T-Scan® III DMD occlusal analysis

Objective: Balanced occlusal force distribution is a critical factor for restorative, prosthetic or orthodontic treatment. It has been postulated that orthodontic treatment may lead to occlusal discrepancies in the arch due to changing the occlusal relationships. This study was conducted to compare the occlusal force parameters between natural dentition patients and a post-orthodontic treatment group.

Method and Materials: Fifty Thai subjects were divided into non-orthodontic and post-orthodontic groups comprised of 25 subjects each (mean age 24.8 years). The T-Scan® III computerized occlusal analysis system was used to record a multi-bite closure for each subject. The initial occlusal contact location, the bilateral percentage force distribution, the percentage force in the anterior and posterior quadrants, and the individual tooth force percentages were calculated for both groups. The Student’s Paired t-Test compared the in-group differences, while a one-way ANOVA analyzed the differences between the two groups.

Results: The initial tooth contacts in both groups were found on the second molars and central incisors. Maximum force was most frequently observed on the left second molar tooth (15.9% non-orthodontic; 25.4% post-orthodontic). The bilateral right-to-left side force distribution (51.36% right–48.96% left) was not statistically different for all subjects, nor was it statistically different between the non-orthodontic (48.67% right–51.36% left) and the post-orthodontic groups (48.96% right–51.05% left). Statistically significant differences were found between the quadrants in both the groups (22.46% anterior–77.57% posterior in non-orthodontic subjects; 10.58% anterior–89.42% posterior in post-orthodontic subjects) (p < 0.01).

Conclusion: A significant occlusal force discrepancy was found in the post-orthodontic subjects, with higher force percentages observed posteriorly and much less percentage force anteriorly, when compared to the natural dentition subjects. T-Scan® III digital occlusal analysis may be recommended for orthodontic case finishing, to make visible to the clinician the severity of the orthodontically created occlusal force imbalance, such that it can be minimized during orthodontic case finishing.     

Computerized analysis of the distribution of occlusal contacts in individuals with Parkinson's disease and temporomandibular disorder

The aims of the present study were to determine the prevalence of temporomandibular disorder (TMD) in a sample of patients with Parkinson's disease (PD) and to analyze the distribution of occlusal contacts.

Method: The sample was composed of patients with PD aged 50–75 years. Temporomandibular disorder was evaluated using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The distribution of occlusal contacts was determined using the portable T-Scan III^® occlusal analysis system during maximum voluntary clenching. Fisher's exact test was used to test the association between TMD and occlusal contact symmetry.

Results: Forty-two individuals with PD were analyzed. The prevalence of TMD was 23.8%. No statistically significant association was found between TMD and occlusal contact symmetry. Moreover, no significant difference in the distribution of occlusal contacts was found between the groups with and without TMD.

Discussion: The present data suggest no association between TMD and occlusal contact asymmetry in individuals with PD.

Conclusion: The results of this study identified a prevalence of 23.8% of TMD signs in subjects with PD and a high frequency of occlusal asymmetry in this sample.     

Three-dimensional morphological characterization of malocclusions with mandibular lateral displacement using cone-beam computed tomography

Objective: The purpose of this study was to evaluate the morphologic characteristics of MLD malocclusions using 3D imaging.

Materials and methods: MLD characteristics were examined using CBCT data in 40 subjects. A 3D Cephalometric analysis was developed to describe the spatial position of the mandible and temporal bones.

Results: Vertical dental heights were shorter and the posterior occlusal plane (POP) presented a steeper sagittal inclination on the shifted side (the side of the laterally displaced bony chin) than on the contralateral side. (p < 0.01). The MLD was related to a superiorly inclined POP Cant in the same direction (r = 0.82; p < 0.01). The shifted side condyle was dislocated medially and was smaller. Temporal bone sagittal inclination showed a more forward and medial inclination on the contralateral side (p < 0.01).

Conclusions: A unilateral decrease in the vertical height of the dentition and the subsequent steeper occlusal plane inclinations correlated with (1) mandibular rotational displacement and condylar lateral displacement, (2) mandibular and condylar morphologic changes (3) changes in temporal bone position.     

Thirty-year follow-up of a TMD case treated based on the neuromuscular concept

Aim:

Occlusal therapy is employed to alleviate the symptoms of a temporomandibular disorder (TMD) at times. However, the long-term effect of occlusal therapy in the masticatory system is not well understood. This case study aims to present a 30-year follow-up of a TMD case.

Methodology:

The patient developed TMD with intermittent closed lock of the left temporomandibular joint (TMJ). Chief complaints included trismus, pain, and noise of the left TMJ during function. The patient’s occlusal disharmony was assessed with use of electronic instruments and corrected based on the neuromuscular concept. A minimum-invasive and reversible approach using adhesive occlusal restorations was used.

Results:

The jaw movement and masticatory muscle activity assessed at the 7- and 23-year follow-ups revealed that the established occlusion was well adapted, and re-established the patient’s functional occlusion system. The patient has been free from TMD symptoms with the corrected occlusion for 30 years.

Conclusions:

Occlusal reconstruction based on the neuromuscular concept can be stably integrated into the patient’s functional occlusion system.     

The effect of dental occlusal disturbances on the curvature of the vertebral spine in rats

Objective:

To determine whether a unilateral increase or decrease in the bite affects the curvatures of the vertebral spine in rats.

Methods:

25 male Sprague Dawley rats were included. Five animals received no alteration on their bite. Bite was increased on 10 animals and molar teeth were extracted on 10 other animals. Frontal and lateral radiographs were taken on days 0, 7, 14 and 21. Distances from landmarks to a true vertical line were measured on both radiographs.

Results:

Repeated measures analysis showed statistically significant differences between the amount of the curvature at the cervical and thoracic spines on frontal and lateral radiographs over time (P<0·05 and P<0·0001). One-way ANOVA computed significant differences (P<0·05) at D14 at the cervical and thoracic spines on both, increased and decreased vertical dimension.

Conclusion:

Alterations in the dental occlusion affects the normal curvatures of the vertebral spine in rats.     

The Scottish Orthodontic Peer Review project: the outcome of treatment and standard of record keeping by orthodontic specialist practitioners in Scotland

Objectives: Assess occlusal outcomes of treatment and clinical record keeping in specialist practice in Scotland.

Design: A retrospective cohort study.

Setting: Specialist practices in Scotland.

Participants: Specialist orthodontists in Scotland.

Methods: Every specialist practitioner in Scotland (51) was invited to take part in the peer review project with 38 (76%) enrolled. Scotland was split into four geographical areas, and each practitioner matched with a colleague from the same area. Practitioners took one day to visit their colleague and score 30 consecutively treated NHS cases using the Peer Assessment Rating (PAR) index. They also assessed the quality of the records taken. Practitioners then swapped roles and assessed their partner’s occlusal outcomes and records.

Results: The mean pretreatment PAR score was 28.6 (SD 3.5). Mean posttreatment PAR score was 3.5 (SD 1.2). Mean reduction in PAR score was 25.1 (SD 3.8). Mean percentage PAR score reduction was 87.7% (SD 3.7%). Overall record keeping scores were written records 100%, study models 99.5%, Orthopantomogram radiograph 99.2%, photographs 86.3%, medical history 75% and consent 40.8%.

Conclusions: Occlusal outcomes achieved by specialist practitioners in Scotland were of a high standard. They maintained a good standard of clinical record collection in most areas examined.     

One-leg standing time with eyes open: comparison between the mouth-opened and mouth-closed conditions

Objective:

Many studies report a significant relationship between the one-leg standing time with the eyes open and the occlusal relationship. To determine the association between proprioception (the periodontal membrane vs muscle spindle) to the one-leg standing time, the authors compared the one-leg standing time with eyes open between mouth-opened and mouth-closed conditions.

Methods:

The study participants were 107 healthy, elderly patients. The authors measured the one-leg standing time with eyes open between mouth-opened and mouth-closed conditions.

Results:

The one-leg standing time was significantly shorter with the mouth opened (21·1±19·1 seconds) than with the mouth closed (25·1±21·4 seconds). Patients whose one-leg standing time was equal or shorter with the mouth opened than with the mouth closed were not different from the other patients with regard to age, handgrip strength, BMI, and the number of remaining teeth.

Discussion:

The vertical mandibular position may affect body balance.     

Effect of orthognathic surgery on masticatory performance and muscle activity in skeletal Class III patients

Objective: To evaluate the effect of double jaw orthognathic surgery (OGS) on masticatory performance and electromyographic activity of the masseter and anterior temporal muscles in skeletal Class III patients.

Methods: Individuals were instructed to chew standardized round tablets of silicone impression material. The cumulative weight percentage was calculated using sieve analysis. The bilateral surface electromyographic activity of the muscles was evaluated. Following the orthodontic treatment, a stabilization splint was fabricated. Patients were instructed to wear it full-time until the surgical procedure occurred. Recordings were performed before the splint application (T0), after the splint application (T1), 1 month after the OGS (T2), and 6–8 months after the OGS (T3).

Results: Median particle size of the chewed silicone material did not differ from T0 to T1 with the use of an occlusal splint (p > 0.05). However, it decreased from 9.46 to 6.92 cm from T2 to T3. From T0 to T3, a statistically significant decrease was found, following the surgical intervention (p < 0.01). A significant decrease in masticatory muscle activity was also observed during the relaxation test from T0 to T3, at which time it reached the control group value.

Discussion: OGS enhanced masticatory function by improving occlusion in individuals with a dentofacial deformity.     

Temporomandibular disorder treatment in a patient wearing removable prostheses: A case report

Aim: The purpose of this intervention was to treat the patient, a 51-year-old woman, who was wearing a maxillary denture and a mandibular bilateral distal-extension partial denture (both unfit) and was suffering from temporomandibular disorder (TMD).

Methodology: The treatment suggested was to construct a superior repositioning splint (SRS), and after remission of the symptomatology, fabricate new dentures.

Results: The occlusal splint was effective and the symptomatology ceased after about five months of treatment. The new dental prostheses were made and followed up for 10 years with no return of the pain.

Conclusions: SRS and subsequent construction of new dentures after remission of the symptomatology was an effective treatment for TMD in the case described.     

Interrelations between orthostatic postural deviations and subjects’ age,sex, malocclusion,and specific signs and symptoms of functional pathologies of the temporomandibular system: a preliminary correlation and regression study

Aims:

Studies on the relationships between postural deviations and the temporomandibular system (TS) functional health are controversial and inconclusive. This study stems from the hypothesis that such inconclusiveness is due to authors considering functional pathologies of the TS (FPTS) as a whole, without taking into account subjects’ specific FPTS signs and symptoms.

Methodology:

Based on the author and collaborators’ previous studies, the present study analyzed data on body posture from a sample of 50 subjects with (30) and without (20) FPTS. Correlation analyses were applied, taking as independent variables age, sex, Helkimo anamnestic, occlusal, and dysfunction indices, as well as FPTS specific signs and symptoms. Postural assessments of the head, cervical spine, shoulders, lumbar spine, and hips were the dependent variables. Linear regression equations were built that proved to partially predict the presence and magnitude of body posture deviations by drawing on subjects’ characteristics and specific FPTS symptoms.

Results:

Determination coefficients for these equations ranged from 0·082 to 0·199 in the univariate, and from 0·121 to 0·502 in the multivariate regression analyses.

Conclusions:

Results show that factors intrinsic to the subjects or the TS may potentially interfere in results of studies that analyze relationships between FPTS and body posture. Furthermore, a trend to specificity was found, e.g. the degree of cervical lordosis was found to correlate to age and FPTS degree of severity, suggesting that some TS pathological features, or malocclusion, age or sex, may be more strongly correlated than others with specific posture patterns.     

The efficacy of a specific stabilization splint

Background:

The use of a Tanner type stabilization splint, fabricated on a leaf gauge articulation for the treatment of patients with disc displacement without reduction, is lacking in the literature.

Objectives:

The purpose of the study is to collect non-controlled, therapy-related observations; in other words, to demonstrate the efficacy of this appliance for the treatment of patients with disc displacement without reduction.

Methods:

The study enrolled 55 patients, 5 men, and 50 women, with the clinical diagnosis disc displacement without reduction, 42 with and 13 without limited mouth opening. All patients received a splint in the musculoskeletally stable centric relation (CR) position. Mouth opening, clinical performance, and the timeframe of splint treatment were assessed.

Results:

For 37 patients with a disc displacement without reduction with limited opening, the largest increase in mouth opening (9·5±5·6 mm) occurred in the first week (7·9±2·5 days). No occlusal adjustment of the splint was needed during the treatment sequence. For three patients, treatment took up to 3 months (8·1%), for 13 patients, between 3 and 6 months (35·1%), and for 17 patients, within a year (45·9%), making a total of 89·1% successfully treated patients. Out of 50 patients, 29 had a total resolution of signs and symptoms, whereas 21 patients still suffered from solitary temporomandibular disorder (TMD) signs.

Conclusion:

A Tanner type stabilization splint, fabricated in the musculoskeletally stable CR position, appears to be an effective and efficient means for the treatment of patients with disc displacement without reduction. Its efficacy makes it eligible to be tested in a randomized controlled trial.

Clinical implications:

The efficacy of this specific splint, fabricated in the musculoskeletally stable CR position, makes it a promising tool to treat TMD patients with disc displacement without reduction.     

Treatment of frictional dental hypersensitivity (FDH) with computer-guided occlusal adjustments

Objective: To verify the efficacy of treating dentin/dental hypersensitivity (DH) to Cold Ice Water Swish testing before and after subjects undergo the Immediate Complete Anterior Guidance Development (ICAGD) computer-guided occlusal adjustment.

Methods: One hundred chronically dysfunctional patients with known cold sensitivity swished ice water intraorally to elicit a DH response scored on a Visual Analog Scale (VAS). The subjects then underwent the ICAGD coronoplasty, which was followed by a second ice water swish scored with a second VAS. The pre to post ICAGD Disclusion Time values and VAS scores were statistically evaluated by the Wilcoxon Signed Rank for Paired Difference test. The subjects were divided into subgroups with DH sensitivities <4 and ≥4, and analyzed. Limitations were as follows: abfractions were not quantified, dysfunctional symptom resolution was not determined, each subject was their own control, one clinician administered all ice water tests, and protrusive excursions were not included.

Results: Disclusion Time reductions from ICAGD were significant (2.11–0.55 s. p = 0.0000). The DH score changes showed highly significant decreases from pre to post ICAGD (p < 0.0001).

Conclusions: A partial etiology for cold tooth sensitivity exists, resultant from prolonged occlusal surface excursive movement frictional contacts. This cold sensitivity can be lessened with measured, computer-guided occlusal adjustments.     

Inter-arch digital model vs. manual cast measurements: Accuracy and reliability

Objectives: The purpose of this study was to evaluate the accuracy and reliability of inter-arch measurements using digital dental models and conventional dental casts.

Methods: Thirty sets of dental casts with permanent dentition were examined. Manual measurements were done with a digital caliper directly on the dental casts, and digital measurements were made on 3D models by two independent examiners. Intra-class correlation coefficients (ICC), a paired sample t-test or Wilcoxon signed-rank test, and Bland–Altman plots were used to evaluate intra- and inter-examiner error and to determine the accuracy and reliability of the measurements.

Results: The ICC values were generally good for manual and excellent for digital measurements. The Bland–Altman plots of all the measurements showed good agreement between the manual and digital methods and excellent inter-examiner agreement using the digital method.

Conclusion: Inter-arch occlusal measurements on digital models are accurate and reliable and are superior to manual measurements.