Is dynamic occlusal design necessary for anterior guidance recovery in the computer-aided design process? An in vitro study.

OBJECTIVES: This study aimed to assess the effectiveness of patient-specific motion in restoring anterior guidance and to investigate the influence of occlusal plane position within a virtual articulator on the design of the anterior guide slope for incisors. METHODS: Twenty participants' intraoral scan, occlusal plane position, and jaw motion data were recorded. The maxillary anterior teeth were virtually prepared, and the crowns were designed based on average virtual articulator (AVR), personalized virtual articulator (ART), and patient-specific motion (PSM). The anterior guide slope of maxillary central incisors (S1, S2, Sc, Sp) and the mesio-distal angle (MDA) of the canine of prostheses were compared to that of natural teeth (NAT). One-Way ANOVA was utilized to evaluate the effectiveness of the three methods in restoring the anterior guidance of maxillary anterior teeth. RESULTS: The comparison of Sp and MDA showed no significant difference between the PSM and NAT groups (p > 0.05). However, Sp of the ART group was significantly smaller, while MDA was higher than that of the NAT group (p < 0.05). Sp did not differ significantly (p > 0.05) when the angle of the occlusal plane (AOP) was small. As the AOP increased, Sp of the ART and AVR groups were significantly smaller than that of the NAT group (p < 0.05). With a large AOP, Sp of the ART group was notably smaller than that of the NAT group (p < 0.05), while there was no significant difference between the AVR and NAT groups (p > 0.05). CONCLUSIONS: Occlusal design based on patient-specific motion proved more effective in restoring natural anterior guidance. The anterior guidance of prostheses designed using a virtual articulator was influenced by occlusal plane position. CLINICAL SIGNIFICANCE: The utilization of a jaw motion tracer facilitated the transfer of personalized occlusal plane positions and recorded jaw motion, which can be integrated into the digital prosthetic workflow for virtual occlusion adjustment. Occlusal design based on patient-specific motion more effectively restored lingual guidance of maxillary anterior crowns.

A Comparison of Occlusal Schemes with Condylar Inclination and Anterior Guidance in Dentate Individuals.

PURPOSE: A Comparison of Occlusal Schemes with Condylar Inclination and Anterior Guidance in Dentate Individuals Methods. Twenty-six dentate patients between the ages of 18 to 30 of Indian Origin with canine-guided occlusion and 26 patients with group function occlusion were included in the study. The School of Articulator Munich (SAM) Axioquick system was used to assess the condylar guidance and eccentric tracings of the patients. For analyses, Student's t-test was used. For quantitative data, the mean and standard deviation were calculated. For all the statistical analysis the probability of type-I error of 0.05 was considered statistically significant. RESULTS: The mean condylar guidance for canine guided and group function occlusion on the right side was 38.4 ±12.7 and 30.5 ±12.5 and on the left side was 36.5 ±13.0 and 27.5±12.0 degrees with statistically significant difference [P value: 0.01]. The condylar guidance, incisal guidance, Bennett angle, protrusion, left lateral, right lateral, and left and right lateral angles were analyzed statistically between the two types of occlusions. The results showed a statistically significant difference between the two groups for all parameters except right condylar guidance. Furthermore, all the parameters were higher in canine guided occlusion group over group function occlusion. CONCLUSIONS: Within the study limitations, it was concluded that the condylar guidance was steeper in canine guided occlusion than in group function occlusion. The eccentric parameters were steeper in canine guided occlusion than in group function occlusion. CLINICAL SIGNIFICANCE: This study showcases that the condylar guidance might not play a major role in determining the occlusal scheme but, the incisal guidance determines the occlusal scheme predominantly in class 1 occlusion patients.

A retrospective five-year survey on the treatment outcome of disclusion time reduction (DTR) therapy in treating temporomandibular dysfunction patients.

OBJECTIVE: To assess the five-year long-term quality of life of patients who were treated with Disclusion Time Reduction Therapy (DTR). METHODS: Thirty occluso-muscular disorder patients responded to two questionnaires about their symptom intensities, frequencies, and pain levels that were given to the patients before DTR therapy and five years after. Both surveys were subjected to the Wilcoxon signed-rank test to compare differences in the reported intensities, frequencies, and pain levels. RESULTS: A statistically significant reduction was found between the pre- and five-year post-DTR treatment intensities, frequencies, and pain scores (p < 0.05). CONCLUSION: The chronic pain intensity and frequency observed in patients with occluso-muscular disorders can be markedly reduced by Immediate Complete Anterior Guidance Development (ICAGD)/DTR therapy, while improving the patient's overall long-term quality of life. Many pre-ICAGD/DTR daily chronic and painful, occluso-muscular symptoms were no longer present years after undergoing ICAGD/DTR treatment.

A Multi-Center Disclusion Time Reduction (DTR) Randomized Controlled Occlusal Adjustment Study Using Occlusal Force and Timing Sensors Synchronized with Muscle Physiology Sensors.

Objective-To perform a Randomized Controlled Trial (RCT) Disclusion Time Reduction (DTR) study at five Dental Colleges, using intraoral sensors and muscular electrodes. Methods and Materials-One hundred students were randomly assigned to a treatment group to receive the ICAGD coronoplasty, or a control group that received tooth polishing. All subjects answered symptom questionnaires: Beck Depression Inventory-II, Functional Restrictions, and Chronic Pain Symptom and Frequency. Subjects self-reported after ICAGD or placebo at 1 week, 1 month, 3 months, and 6 months. The Student's t-Test analyzed the measured data. The Mann-Whitney U Test analyzed the subjective data (Alpha = 0.05). Results-The Disclusion Times, BDI-II scores, and Symptom Scales were similar between groups prior to treatment (p > 0.05). At 1 week, all three measures reduced in the treatment group, continuing to decline over 6 months (p < 0.05), but not for the controls (p > 0.05). Symptom Frequency, Functional Restrictions, and Pain Frequencies were higher in the treated group (p < 0.05), but declined after ICAGD compared to the control group (p < 0.05). Conclusions-ICAGD reduced Pain, Functional Restrictions, Symptom Frequency, and Emotional Depression within 1 week, which continued for 6 months. The tooth polishing did not initiate a placebo response.

A 3-year prospective cohort study on mandibular anterior cantilever restorations associated with screw-retained implant-supported prosthesis: An in vivo study.

Aim: The aim of this study is to evaluate the survival of single implant supported cantilever prosthesis (ISCP) replacing missing two adjacent natural teeth in the anterior mandible. Settings and Design: In vivo - Prospective cohort study. Materials and Methods: Thirty patients with missing both mandibular central incisors were selected. A single implant was used to replace the missing teeth and restored with cantilever screw-retained prosthesis. Twenty-two patients were followed for 3 years for the implant and prosthetic success. Statistical Analysis Used: Weibull test for survival probability. Results: Survival probability of the ISCP for the first 100 days was found to be 97.55%, for 200 days, it was 71.4%, for 250 days, it was 46%, and for 365 days, it was 3.9%, i.e., 20 prosthesis had screw loosening after prosthetic loading. However, it increased to 95.2% at the end of 3 years. Conclusion: Screw-retained ISCP developed early technical complications. After prosthetic loading, the survival probability of the screw-retained ISCP was very low (3.9%) at one year, which increased to 95.2% after retightening and retorquing of the abutment screw, porcelain repair and conformation of the tongue to the prosthesis. The most common prosthetic failure was screw loosening (81%), followed by porcelain fracture (14.3%), and implant survival of 95% at the end of three years.

Guía Anterior Completa Inmediata (GACI) / Inmediate Complete Anterior Guidance (ICAG)

Resumen La Guía Anterior es algo muy importante en el resultado final de nuestros pacientes, en la Ortodoncia y en todas las ramas de la Odontología. Tiene un efecto inmediato a nivel de los músculos elevadores en el movimiento de protusiva y lateralidad antes de llegar al contacto final, tienen una sobre carga de fricción a nivel de premolares y molares, se produce una liberación de ácido láctico excesiva en los temporales y maseteros (Fig. 1), que afecta a los músculos provocando dolores en los pacientes. (AU)

Abstract The Anterior Guide is something very important in the final result of our patients, in Orthodontics and Dentistry. It has an immediate effect at the level of lifting muscles when the movement of protrusive and laterality takes action before reaching the final contact they will have an overload of friction on premolars and molars, an excessive release of lactic acid occurs in the temporal and masseter. It affects the muscles causing pain in patients. (AU)

Functional and esthetic improvement through reconstruction of anterior guidance using the modified Dahl principle and copy-milled technique of CAD/CAM system: A case report / 대한치과보철학회지

The anterior guidance is one of the important factors in prosthodontic treatment of anterior teeth. The lingual surface shape of anterior restorations is so critical that small errors of treatment procedure can cause discomfort of the patient and disharmony of the dentition. If the anterior restorations are achieved harmonious anterior guidance through the fabrication and adjustment of provisional restorations, it is important to accurately reproduce the lingual surface shape of provisional restorations as the final prosthesis. In this case report, it was used the modified Dahl principle and copy-milled technique of computer-aided design/computer-aided manufacturing (CAD/CAM) system for systematic diagnosis and treatment. Therefore, we tried to reconstruct the restoration shape more precisely by setting the appropriate anterior guidance and superimposing the digital image of the abutment teeth and the provisional restorations. Thus, by promoting functional and esthetic recovery, this case report demonstrates satisfying results to both the patients and dentist.

Maxillary anterior prosthetic treatment concerning anterior guidance of a patient who lost stable holding contact / 대한치과보철학회지

Recently, many patients undergo anterior prosthetic treatment for esthetic reasons. In some patients complain about functional reasons such as inaccurate pronunciation and occlusal discomfort after the treatment. Anterior teeth are important esthetically but in the occlusal point of view, anterior guidance is the second most important factor in occlusion, next to centric relation. Failure to determine an appropriate anterior guidance might lead to posterior occlusal interference, which can highly affect the stability of the posterior teeth. Also, discomfort might occur if the customized interior guidance is not in harmony with the patient's envelope of function. The patient in this case complained of overall discomfort in the maxillary anterior area after prosthetic treatment. The expressed difficulty in pronunciation, unstable occlusion due to lack of stable holding contact and discomfort of the facial muscles. Maxillary anterior prostheses were refabricated through systematic diagnosis and treatment and thus, this case presents esthetical and functional satisfaction to both the patient and the dentist.

Re-establishment of occlusal plane in a patient with a failed implant prosthesis / 대한치과보철학회지

A non-physiological occlusal plane caused by continuous tooth loss, occlusal wear, and failure of a prosthesis may result in an unattractive appearance and functional problems, such as reduced masticatory efficiency and occlusal interference. Therefore, when undertaking prosthetic treatment for edentulous patients or patients with a collapsed occlusal plane, it is important to establish an occlusal plane that is compatible with masticatory function. The patient in this case report had undergone restoration of a completely edentulous maxilla using an implant-supported fixed prosthesis. On follow-up examination in the following 6 years, mechanical complications were observed in the existing implant prosthesis, including porcelain chipping, occlusal wear, and screw loosening. Moreover, due to occlusal wear and supraeruption of the opposing anterior teeth, as well as loss of some posterior teeth, the occlusal plane had collapsed. Following diagnosis, the patient underwent full mouth rehabilitation, involving additional implant installation in edentulous sites, recreation of the existing prosthesis, and prosthetic restoration of all remaining teeth.

A case of full mouth rehabilitation with orthodontic treatment in patient with extensive tooth erosion and wear using monolithic zirconia prostheses / 대한치과보철학회지

Extensive dental erosion and wear will cause serious loss of function and aesthetics in the mouth. In order to recover this condition, careful analysis of the patient's bite relationship is required. In particular, a treatment plan should be established considering the possibility of reproduction of the vertical dimension and centric relation, and appropriateness of the occlusal plane and anterior guidance. Also, the choice of prosthetic materials is an important consideration in patients with severe wear. In this case, patients with overall wear and erosion on tooth was established anterior guidance by orthodontic treatment and fully restored with monolithic zirconia, without increasing vertical dimension.

Functional and esthetic improvement through systematic diagnosis and treatment procedures in patient with unaesthetic anterior teeth proportion because of tooth wear: A case report / 대한치과보철학회지

It is reported that the causes of unaesthetic proportion of anterior teeth vary widely. Especially, when the unaesthetic tooth proportion of the mandibular incisors arises due to the wear of the anterior teeth accompanied by the compensation of the alveolar bone, it may cause serious functional and aesthetic problems. In such case, it should be considered that the evaluation of vertical dimension and tooth proportion as well as smile line, soft tissue and hard tissue morphology. And, increase of vertical dimension or clinical crown lengthening followed by prosthodontic restorations is needed to improve the interdental mesial/distal, width/length ratio considering the anterior guidance. This case report demonstrates functional and aesthetic improvements through systematic diagnosis and treatment procedures in a 48-year-old male patient with unaesthetic anterior teeth proportion because of tooth wear accompanied by the compensation of alveolar bone and defect of several central incisors due to chronic periodontitis.

[Establishment of rat models with altered anterior guidance and observation of histological changes in temporomandibular joint synovium].

OBJECTIVE: This study aims to establish a stable animal model with altered anterior guidance and investigate histological changes on temporomandibular joint (TMJ) synovium in rats. METHODS: Thirty-two rats were divided into four groups, namely, control group, anterior-guidance-deficient group (T1), and anterior guidance inclined up to 15 degree (T2) and 30 degree (T3) groups. Metal crowns that add 15 and 30 degrees to the palatal side were cemented to the incisors of maxilla to increase the inclination of anterior guidance. The low-speed diamond wheel shorts for both upper and lower incisors of rats were applied to avoid contact between anterior teeth in all direction, thus establishing an anterior guidance deletion model. TMJ joints on one side of two animals in each group were harvested after 3, 7, 14, and 28 days. Pathological changes were investigated in the TMJ synovium using hematoxylin-eosin (HE) staining. RESULTS: The weight of T1 decreased briefly at first, and then increased slightly (P<0.05). The weight of T3 obviously reduced and then slowly increased, but remained below the initial weight (P<0.05). T3 manifested obvious synovial lining proliferation and vascular dilation (P<0.05). CONCLUSIONS: The rat model of anterior guidance inclined up to 30 degree could imitate the pathological features of TMJ synovium with excessive increase in anterior guidance. A higher inclination of anterior guidance might cause more damage of TMJ synovium. The effect of anterior guidance deletion on TMJ synovium is yet to be determined.
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Disclusion time reduction therapy in treating occluso-muscular pains.

Disclusion time reduction (DTR) is an objective treatment protocol using T-Scan III (digital analysis of occlusion) and electromyography for treating occlusally activated orofacial pains. Chronic occluso-muscle disorder is a myogenous subset of temporomandibular disorder symptoms. These muscular symptoms are induced within hyperactive masticatory muscles due to prolonged disclusion time, occlusal interferences, and occlusal surface friction that occur during mandibular excursive movements. This case report describes a patient treated by DTR therapy, whereby measured pretreatment prolonged disclusion time was reduced to short disclusion time using the immediate complete anterior guidance development enameloplasty, guided by T-Scan occlusal contact time and force analysis synchronized with electromyographic recordings of four masticatory muscles.

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.

Maxillary anterior implant restoration with appropriate anterior guidance using T-Scan in a patient with full fixed prostheses / 대한치과보철학회지

In implant restorations, it is difficult for the patient to percept any symptoms. In addition, they are absent of shock absorbers, which can lead to mechanical failure if stress distribution is not considered. Since maxillary anterior multiple-implant restorations play a significant role in guiding the functional movement of the mandible by distributing lateral force, it is crucial to form appropriate occlusion. The use of the T-scan system is more advantageous in assessing ‘dynamic occlusion’, such as the change of occlusion over time, the amount of tooth contact during functional movement, and assessing the occlusion in the less-visible posterior teeth. The case is reported as it has satisfactory results in harmonious anterior guidance of a maxillary anterior multiple-implant restoration using T-scan analysis.

Establishment of rat models with altered anterior guidance and observation of histological changes in temporomandibular joint synovium / 华西口腔医学杂志

<p><b>OBJECTIVE</b>This study aims to establish a stable animal model with altered anterior guidance and investigate histological changes on temporomandibular joint (TMJ) synovium in rats.</p><p><b>METHODS</b>Thirty-two rats were divided into four groups, namely, control group, anterior-guidance-deficient group (T1), and anterior guidance inclined up to 15 degree (T2) and 30 degree (T3) groups. Metal crowns that add 15 and 30 degrees to the palatal side were cemented to the incisors of maxilla to increase the inclination of anterior guidance. The low-speed diamond wheel shorts for both upper and lower incisors of rats were applied to avoid contact between anterior teeth in all direction, thus establishing an anterior guidance deletion model. TMJ joints on one side of two animals in each group were harvested after 3, 7, 14, and 28 days. Pathological changes were investigated in the TMJ synovium using hematoxylin-eosin (HE) staining.</p><p><b>RESULTS</b>The weight of T1 decreased briefly at first, and then increased slightly (P<0.05). The weight of T3 obviously reduced and then slowly increased, but remained below the initial weight (P<0.05). T3 manifested obvious synovial lining proliferation and vascular dilation (P<0.05).</p><p><b>CONCLUSIONS</b>The rat model of anterior guidance inclined up to 30 degree could imitate the pathological features of TMJ synovium with excessive increase in anterior guidance. A higher inclination of anterior guidance might cause more damage of TMJ synovium. The effect of anterior guidance deletion on TMJ synovium is yet to be determined.
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The effect of disocclusion time-reduction therapy to treat chronic myofascial pain: A single group interventional study with 3 year follow-up of 100 cases.

PURPOSE: The purpose of this study is to evaluate the longevity of reduced disclusion time in treating and removing myofascial pain dysfunction symptoms following the T-Scan-based, immediate complete anterior guidance development (ICAGD) coronoplasty. This measured occlusal adjustment has been shown to reduce the muscle hyperactivity of myofascial pain. METHODS: Myofascial pain symptomatic patients were recruited as per the diagnostic criteria for temporomandibular disorders (TMDs), including the clinical protocol and assessment instruments outlined by the international RDC/TMD consortium network (version: January 20, 2014) to assess the efficacy of reduced disclusion time in left and right lateral excursions to resolve the myofascial pain symptoms. As per the inclusion and exclusion criteria, 100 cases were treated with ICAGD in three visits, each 1 week apart. Recall disclusion time measurements were recorded every 3 months over 3 years. The RDC/TMD questionnaire was used for symptom assessment at every recall visit. ICAGD brought pretreatment prolonged disclusion time down to <0.4 s, as quantified from T-Scan force and time data records, while the subjects were assessed for symptom relief. The Wilcoxon signed-rank test was used for statistical analysis (P < 0.05). RESULTS: Changes in the intensity of many symptoms from reducing the disclusion time to <0.4 s were statistically significant from treatment day 1, and onward through the 3-year period of observation (P < 0.05). CONCLUSION: The results indicate that ICAGD reduces the musculoskeletal symptoms of myofascial pain, such that this methodology increases clinical therapeutic success.

Rehabilitation of a patient with non-syndromic partial oligodontia.

Oligodontia is defined as a congenital tooth agenesis with the absence of six or more permanent teeth. This clinical report describes a patient with non-syndromic partial oligodontia, with retained deciduous teeth and the absence of 16 permanent teeth. Anterior esthetic problems were caused by interarch tooth size discrepancy, interdental space, aberrant tooth dimensions, and the absence of centric contacts of the anterior teeth. Prosthetic restoration after orthodontic and implant treatment was performed with a multi-disciplinary team approach. Favorable functional and esthetic results were obtained using a definitive prosthesis.

Application of ARCUS digma I, II systems for full mouth reconstruction: a case report

Transferring condylar and anterior guidance on an articulator is essential to the diagnosis of a patient for full mouth reconstruction. In this clinical report, ARCUS digma I system was used to measure inherent condylar guidance of a patient requiring full mouth reconstruction in preoperate treatment, and the patients was given provisional restoration based on a functional anterior guidance. Then, ARCUS digma II system was used to mount the final casting model on an articulator, and the definitive prosthesis was placed in the patient. An esthetic and functionally proper clinical result regarding inherent condylar path of the patient was observed, and results from comparison of the two systems are given in this case.

Rehabilitation of a patient with non-syndromic partial oligodontia

Oligodontia is defined as a congenital tooth agenesis with the absence of six or more permanent teeth. This clinical report describes a patient with non-syndromic partial oligodontia, with retained deciduous teeth and the absence of 16 permanent teeth. Anterior esthetic problems were caused by interarch tooth size discrepancy, interdental space, aberrant tooth dimensions, and the absence of centric contacts of the anterior teeth. Prosthetic restoration after orthodontic and implant treatment was performed with a multi-disciplinary team approach. Favorable functional and esthetic results were obtained using a definitive prosthesis.