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Aim: Assessment of occlusion changes during laboratory phase of relining is essential to evaluate the occlusal discrepancies that could get incorporated in the denture with the use of different relining materials. Since the long term stability and functional success of the denture is heavily influenced by occlusion, an In-vitro study to assess these changes after relining is warranted. The aim of the study is to evaluate the changes in occlusion during laboratory phase of relining procedure. Settings and Design: This is an in vitro study with a total of 30 specimen. Materials and Methodology: A total of 30 maxillary standardized dentures were fabricated after mounting on a semi adjustable articulator. These samples will be divided into three groups based on the relining material used (Autopolymerizing resin, Heat-cure resin, Tissue conditioner). The vertical dimension, Centric contact points and eccentric contact points were measured before and after relining. Statistical Analysis Used: The variables were tested to see if they had a normal distribution using the Shapiro-Wilk test. Parametric distribution was seen for ECP leading to further comparison using one way analysis of variance (ANOVA). Non-parametric distribution was found while testing the VD, CCP leading to adoption of Kruskal-wallis test for comparison of groups. Dunn Bonferroni test was done for VD since results were significant. Results: The results of this in-vitro study showed statistically significant difference with respect to change in vertical dimension in all groups pre and post relining (P = 0.005). The centric contact points showed lesser variation in position when comparing the pre to the post relining phase with the use of autopolymerising resins, whereas heat cure resins and tissue conditioners showed statistically significant difference in the centric point contacts post relining. No statistically significant changes were seen in eccentric occlusion post relining in all groups. Tissue conditioners showed minimum mean changes in eccentric contacts. Conclusion: Within the limitations of this study, the use of autopolymerising resins depicted the most stable results with respect to occlusion, for relining of dentures.

Aim: Assessment of occlusion changes during laboratory phase of relining is essential to evaluate the occlusal discrepancies that could get incorporated in the denture with the use of different relining materials. Since the long term stability and functional success of the denture is heavily influenced by occlusion, an In-vitro study to assess these changes after relining is warranted. The aim of the study is to evaluate the changes in occlusion during laboratory phase of relining procedure. Settings and Design: This is an in vitro study with a total of 30 specimen. Materials and Methodology: A total of 30 maxillary standardized dentures were fabricated after mounting on a semi adjustable articulator. These samples will be divided into three groups based on the relining material used (Autopolymerizing resin, Heat-cure resin,Tissue conditioner).The vertical dimension, Centric contact points and eccentric contact points were measured before and after relining. Statistical Analysis Used: The variables were tested to see if they had a normal distribution using the Shapiro- Wilk test. Parametric distribution was seen for ECP leading to further comparison using one way analysis of variance (ANOVA). Non-parametric distribution was found while testing the VD, CCP leading to adoption of Kruskal-wallis test for comparison of groups. Dunn Bonferroni test was done for VD since results were significant. Results: The results of this in-vitro study showed statistically significant difference with respect to change in vertical dimension in all groups pre and post relining (P = 0.005). The centric contact points showed lesser variation in position when comparing the pre to the post relining phase with the use of autopolymerising resins, whereas heat cure resins and tissue conditioners showed statistically significant difference in the centric point contacts post relining. No statistically significant changes were seen in eccentric occlusion post relining in all groups. Tissue conditioners showed minimum mean changes in eccentric contacts. Conclusion: Within the limitations of this study,the use of autopolymerising resins depicted the most stable results with respect to occlusion,for relining of dentures. [ABSTRACT FROM AUTHOR]

Introduction: The lack of academic agreement in the practical or clinical use of declarative knowledge can generate unnecessary confusion and miscommunication. The concept Centric Occlusion (CO) is part of the body of declarative knowledge in dentistry, but its definition remains unclear. Objective: To ascertain the CO concept in articles published in dental journals as a study case for the dentistry "corpus" of declarative knowledge. Methodology: The alternative definitions of CO used by the GPT (Glossary of Prosthodontic Terms) from 1956–1977, 'CO as a synonym for maximum intercuspal contact (MIC)', or by the GPT from 1987–2017, 'CO may or may not coincide with MIC', were searched in the articles. The association between the CO definition used and variables such as article aims, journal scope and authors specialty was assessed. Results: Eight hundred and twelve articles were analysed. The widespread use of CO as synonym of MIC was the main finding and was significantly associated to the Orthodontics field. The CO definition according to the GPT 1987–2017 was less frequently observed but appeared in all dentistry fields, showing a significant association with the Oral Rehabilitation field. The difficulty of incorporating the current definition of CO (by GPT) into the main clinical discussions was evidenced all the long of the review process. Conclusion: The lack of consensus in the concept use was confirmed by the present study case, showing the influence of specific fields in Oral Health declarative knowledge. This methodology can provide a tool to the academy to assess controversial terms or concepts in Oral Health education, thus facilitating the critical and reflexive learning by students. [ABSTRACT FROM AUTHOR]

Background: Evaluating occlusal contacts during maximum intercuspation is one of the requirements for guiding clinicians during occlusal corrections and has been a topic of considerable importance for researchers over many decades. Objective: This systematised review intends to evaluate the average number of occlusal contacts present in dentate adults, as documented within the dental literature over the past four decades (1980s–2022). Methodology: Electronic searches were conducted in three databases (PubMed, Livivo and Ovid) using a combination of search words. Results: A total of 651 records were identified through PubMed and another 37 records through Livivo and Ovid databases. After eliminating duplicates and irrelevant records, 168 records were screened. Full texts of 61 articles remained, out of which 18 relevant papers that presented occlusal contacts in quantifiable value were considered. Various occlusal indicators, such as articulating paper, wax sheets, shimstock foil, impression material, gnathodynamometers and digital occlusal analysis systems, were used to evaluate occlusal contacts. The number of occlusal contacts widely ranged from 11 to 70. These variations likely depends upon the type and technique of occlusal indicator used, diversity among sampled populations and differing data collection procedures. Conclusion: Different methods of identifying occlusal contacts in the intercuspal position yield different numbers and patterns of contacts, depending on the nature and physical properties of the indicators used. [ABSTRACT FROM AUTHOR]

AIM AND OBJECTIVE: To evaluate and compare the position of the tongue from rest to centric occlusion in subjects with skeletal class Ⅱ division 1 and skeletal class Ⅱ division 2 malocclusions with subjects of skeletal class Ⅱ normal occlusion. MATERIAL AND METHODS: The study was conducted on 30 individuals equally divided into three groups of skeletal class Ⅱ division (div) 1, skeletal class Ⅱ div 2, and skeletal class Ⅰ normal occlusion. The study was conducted on two lateral cephalograms for each subject: one taken at rest and one in centric occlusion. RESULTS: On evaluation of tongue posture, a statistically significant difference was observed at the middle portion of the tongue in class Ⅱ div 1 malocclusion, and at the posteromedial portion of the dorsum of the tongue in class Ⅱ div 2 skeletal malocclusions as the tongue moved from rest to centric occlusion. While statistically significant differences were found between class Ⅱ div 2 malocclusion and class Ⅰ normal occlusion, no statistically significant differences were observed between class Ⅱ div 1 and class Ⅱ div 2 malocclusions. CONCLUSION: Tongue position was observed to be the same in both class Ⅱ div 1 and class Ⅱ div 2 malocclusions, with no statistically significant differences. However, a great change was seen in the tongue position from rest to centric occlusion. [ABSTRACT FROM AUTHOR]

Background: Any irregularity of the teeth or a mal-relationship of the dental arches is known as malocclusion. Among all the oro-facial problems, tooth decay is considered the most prevalent one followed by periodontal disease and dental malocclusion. Dental malocclusion is not a life-threatening condition. However, it is closely related to an individual's self-esteem and psychosocial wellbeing. The prevalence of malocclusion varies among different ethnic groups, age-groups, and gender. Objectives: This study was conducted with the objective to find out the prevalence of normal occlusal traits and to identify the proportion of different types of malocclusions among dental and nursing students of Seven North-Eastern states studying at a tertiary care Medical Institute. Methods and materials: This cross-sectional study included 432 students with a mean age of 21.42 years, who satisfied the inclusion criteria. Inclusion criteria consisted of the presence of all permanent teeth with or without third molars. The oral cavity was examined using a sterile mouth mirror and flashlight followed by evaluation of all the occlusal relationships in centric occlusion position (COP). COP was achieved by asking the participant to swallow, and then to bite on his or her teeth together. The occlusion traits were assessed as normal occlusion or malocclusion using the first permanent molars as described by E.H. Angle and deviation from line of occlusion. Descriptive statistics like mean and proportions were calculated. Results: The prevalence of normal occlusal traits was 48.4%, and that of malocclusion was 51.6%. Class I malocclusion was most prevalent occlusal trait followed by Class II malocclusion and Class III malocclusion showed the least prevalence. Conclusions: Class I malocclusion was most prevalent followed by Class II malocclusion and Class III malocclusion showed the least prevalence.

Introduction: Centric Relation (CR) is the only physiological position which is repeatable, recordable and reproducible for prosthodontic rehabilitation. A missed CR can give rise to faulty occlusal relationships leading to a life time of trauma to the temporomandibular joints. Literature has various methods outlined to locate and record the CR but it’s confusing as to which method is best suited to take the condyles into CR position. Hence, this systematic review was conducted to find an answer to this very question. Aim: To find a reliable clinical technique to guide the mandible to a recordable, repeatable and reproducible CR position. Materials and Methods: The present systematic review was conducted from July 2019 to October 2019 at School of Dental Sciences, KIMSDU, Maharashtra. A 20-year comprehensive literature review was undertaken aiming to arrive at a reliable and repeatable method to guide the mandible to CR following the Preferred Reporting Items for Systematic Reviews and Meta Analyses (PRISMA) and Patient Intervention Comparison Outcome (PICO) guidelines to the highest possible extent. The research material was sifted through MEDLINE (PubMed) –{(“CR technique”) (MeSH terms) AND/OR (Retruded mandibular position”) (MeSH terms)}, Cochrane library “CR techniques” and Google Scholar “CR techniques OR Retruded mandibular position” search engines. Cochrane collaboration tool was used to assess the risk of bias for the Randomised Controlled Trial, Methodological I index for non RCTs (MINOR). Quality and strength of the existing evidence was appraised by both the authors through Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Results: Online database search was conducted from January 1998 to September 2019 resulting in a total of 950 articles being shortlisted. Post-screenings, using the exclusion criteria, nine articles of the total articles were reviewed. These were reviewed individually by both the authors and discussed for various techniques to guide the mandible to CR. The ultimate outcome of the review was that the clinicians are required to fall back on time tested models, scientifically sound and technically correct and uncomplicated to execute methods which have proven to yield the most excellent outcomes at zero or minimal cost. One such method is undoubtedly Dawson’s Bimanual Technique. Bimanual technique in supine position coupled with a simple anterior deprogrammer has consistently resulted in a physiological CR position that is recordable, repeatable and reproducible. Conclusion: The primary outcome of this systematic review is that Dawson’s bimanual manipulation technique is superior to other techniques; primarily when carried out in supine position.

Any irregularity of the teeth or a mal-relationship of the dental arches is known as malocclusion. Among all the oro-facial problems, tooth decay is considered the most prevalent one followed by periodontal disease and dental malocclusion. Dental malocclusion is not a life-threatening condition. However, it is closely related to an individual's self-esteem and psychosocial wellbeing. The prevalence of malocclusion varies among different ethnic groups, age-groups, and gender. This study was conducted with the objective to find out the prevalence of normal occlusal traits and to identify the proportion of different types of malocclusions among dental and nursing students of Seven North-Eastern states studying at a tertiary care Medical Institute. This cross-sectional study included 432 students with a mean age of 21.42 years, who satisfied the inclusion criteria. Inclusion criteria consisted of the presence of all permanent teeth with or without third molars. The oral cavity was examined using a sterile mouth mirror and flashlight followed by evaluation of all the occlusal relationships in centric occlusion position (COP). COP was achieved by asking the participant to swallow, and then to bite on his or her teeth together. The occlusion traits were assessed as normal occlusion or malocclusion using the first permanent molars as described by E.H. Angle and deviation from line of occlusion. Descriptive statistics like mean and proportions were calculated. The prevalence of normal occlusal traits was 48.4%, and that of malocclusion was 51.6%. Class I malocclusion was most prevalent occlusal trait followed by Class II malocclusion and Class III malocclusion showed the least prevalence. Class I malocclusion was most prevalent followed by Class II malocclusion and Class III malocclusion showed the least prevalence. [ABSTRACT FROM AUTHOR]

Objective: To assess the masticatory muscle activities in patients with temporomandibular disorders (TMD) with centric relation (CR)-maximum intercuspation (MI) discrepancy and absence of anterior/lateral guidance by electromyography (EMG).Methods: Forty-six patients with TMD and 34 controls underwent clinical evaluations and EMG recordings at baseline. Twenty-three patients and 17 controls wore a stabilization splint. The remaining subjects were followed up without any intervention. After 3 months, the EMG recordings and clinical evaluations were repeated.Results: At baseline, the EMG values at rest and EMG value variations after movements in patients were higher than those in controls. After treatment, no difference was observed between EMG values of patients and controls.Conclusion: In the present study, patients with TMD had abnormal muscular activities. The stabilization splint is effective for functional recovery of the masticatory muscles, possibly by eliminating the CR-MI discrepancy and establishing anterior/lateral guidance. [ABSTRACT FROM AUTHOR]

Introduction: Centric Relation (CR) is the only physiological position which is repeatable, recordable and reproducible for prosthodontic rehabilitation. A missed CR can give rise to faulty occlusal relationships leading to a life time of trauma to the temporo-mandibular joints. Literature has various methods outlined to locate and record the CR but it's confusing as to which method is best suited to take the condyles into CR position. Hence, this systematic review was conducted to find an answer to this very question. Aim: To find a reliable clinical technique to guide the mandible to a recordable, repeatable and reproducible CR position. Materials and Methods: The present systematic review was conducted from July 2019 to October 2019 at School of Dental Sciences, KIMSDU, Maharashtra. A 20-year comprehensive literature review was undertaken aiming to arrive at a reliable and repeatable method to guide the mandible to CR following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA) and Patient Intervention Comparison Outcome(PICO) guidelines to the highest possible extent. The research material was sifted through MEDLINE (PubMed) -{("CR technique") (MeSH terms) AND/OR (Retruded mandibular position") (MeSH terms)}, Cochrane library "CR techniques" & Google Scholar "CR techniques OR Retruded mandibular position" search engines. Cochrane collaboration tool was used to assess the risk of bias for the Randomised Controlled Trial, MINOR index for non-RCTs. Quality and strength of the existing evidence was appraised by both the authors through Grading of Recommendations Assessment, Development and Evaluation (GRADE) system. Results: Online database search was conducted from January 1998 to September 2019 resulting in a total of 950 articles being shortlisted. Post-screenings, using the exclusion criteria, nine articles of the total articles were reviewed. These were reviewed individually by both the authors and discussed for various techniques to guide the mandible to CR. The ultimate outcome of the review was that the clinicians are required to fall back on time tested models, scientifically sound and technically correct and uncomplicated to execute methods which have proven to yield the most excellent outcomes at zero or minimal cost. One such method is undoubtedly Dawson's Bimanual Technique. Bimanual technique in supine position coupled with a simple anterior deprogrammer has consistently resulted in a physiological CR position that is recordable, repeatable and reproducible. Conclusion: The primary outcome of this systematic review is that Dawson's bimanual manipulation technique is superior to other techniques; primarily when carried out in supine position. [ABSTRACT FROM AUTHOR]

Occlusal interference causes instability in temporomandibular joint and hyperactivity of mastication muscles which eventually leads to temporomandibular joint dysfunction. Therefore, achieving stable occlusion is important in young patients. It is key factor in optimizing functional occlusion in adulthood. Application of «The ABO Model Grading System» and Mandibular Position Indicator as an additional diagnostic method in children undergoing orthodontic treatment using braces. Thirty-two patients aged 14 to 18 diagnosed with teeth crowding on the upper and lower jaws were examined, then separated in two groups of 16 people each. All patients underwent orthodontic treatment using braces. In group 2, due to application the anthropometrical system of quantitative evaluation ABO with re-fixing the incorrectly arranged braces by indirect bonding method, occlusal interferences were eliminated. MPI analysis showed discrepancy between the central occlusion and the central relation which was not as relevant as in the group 1 (p > 0.05). Using the anthropometric system of quantitative assessment of ABO with subsequent re-fixation of incorrectly placed braces by indirect bonding, effectively improves the MPI. This determines the unity of position between articular condyles on the lower jaw in the centric occlusion and in the centric relation, which allows to get a stable result of orthodontic treatment. [ABSTRACT FROM AUTHOR]

Brief Background The number and distribution of occlusal contacts have been studied by several authors but all of them define the greatest number of occlusal contacts. The phenomenon of dominant occlusal contacts was given but there is a difference in opinion about the strongest contacts. This study was designed to evaluate the strongest occlusal contacts in young adults between the age group (18-26 years) in centric occlusion. Materials and Methods A total of 50 subjects (18-26 years), meeting every exclusion/inclusion criterion were randomly selected. A TScan system with a sensor of suitable size was placed in a sensor holder and held between the two dental arches. A total number of 3 recordings were made for each patient in centric occlusion. Only those records were assumed successful in which the marker of the center of force was projected in the center. Each sensor was used for 5-10 readings. Results The results of this study showed that the strongest contact areas were present on the most posterior teeth in the dentition. This position is also influenced by the total number of teeth present in the dentition as well as while doing any occlusal corrections, the mandibular closure patterns should be evaluated. While registering occlusal contacts, initial as well as final contact positions also should be considered. Conclusion The strongest occlusal contact points are present in the most posterior teeth in 67.33% of the total readings. [ABSTRACT FROM AUTHOR]

Objective: The number and distribution of occlusal contacts in centric occlusion and centric relation have been studied by a number of authors. All these studies have one thing in common-they define the greatest number of occlusal contacts between the molars. The purpose of the present study was to register the maximum clenching forces in centric occlusion, as well as to analyze the anatomic and functional factors that determine their localization on teeth. Method and Materials: The study included 42 subjects, aged 19 to 26 years, with intact dentition and Class I Angle occlusion; 38 persons had 1 to 4 restorations on the premolars and molars. The occlusal contacts were investigated in centric occlusion by the T-Scan system (Sentek) on wax and silicone impressions. The force loads in different sections of the dentition were differentiated by an additionally developed computer program. Results: The T-Scan analysis and the developed computer program revealed that the maximum values of the clenching forces were recorded on the third molars. The strongest contacts found by the T-Scan system were successfully visualized in wax and silicone impressions. Conclusion: The maximum clenching forces of the masticatory muscles recorded by the T-Scan system were located in centic occlusion at the third molars in a dentition of 32 teeth and at the second molars in a dentition of 28 teeth. If the above-mentioned phenomenon is not taken into consideration in clinical practice, occlusal contacts may be created that will unfavorably transfer the specific clenching forces to a more medially located molar in cases of occlusal restoration of the same molar by a restoration or a single crown. [ABSTRACT FROM AUTHOR]

Objective To investigate whether the RW⁃splint could be used to guide or determine the CR position of the lower jaw so as to provide help for the later diagnostic design. Methods 20 class ⅡⅠ malocclusion patients were recruited in orthodontic department of Foshan Stomatological Hospital. They were treated by RW⁃splint for half a year before orthodontic treatment. The overjet of anterior teeth were recorded before and after treatment. Results The over⁃ jet of anterior teeth was (6.792 ± 0.795) mm before treatment and (7.720 ± 0.930) mm after half a year􀆳s treatment. The overjet of anterior teeth had significant difference (t＝6.319, P < 0.01). The overjet change of anterior teeth between be⁃ fore treatment and half year after treatment was (0.928 ± 0.657) mm. Conclusion The RW⁃splint wearing before treat⁃ ment can be used to guide or determine the mandible in the CR position.

Temporomandibular joint (TMJ) forms an integral functional part of stomatognathic system. Position, shape, structure and function of teeth have an influence on the proper functioning and health of TMJ. But a problem associated with TMJ is often neglected, and treatment for it is mostly restricted to palliative therapy. A proper understanding of the underlying cause of temporomandibular joint disorder (TMD) is necessary to device a proper treatment plan. Etiology of TMDs varies from idiopathic reasons to systemic disorders. The option of Gnathological splint is a conservative, safe and an effective mode of therapy for TMDs caused by occlusal discrepancies (fulcrum/interferences). This article presents a case report of a patient with TMD caused by occlusal discrepancy

Background. The aetiology of temporomandibular joint disorders (TMD) is multifactorial, whereas occlusal disharmony is one of the predisposing factors. Researchers still discuss the relation between occlusion and TMD. Objective. The study aims to investigate the relation between static occlusal parameters and TMD clinical symptoms using T-Scan II analysis system. Material and methods. The sample consisted of 44 persons divided into the treatment group of 20 TMD patients and the control group of 24 subjects without TMD. The main task of T-Scan II computerized occlusal analysis system was to record every patient’s occlusion and estimate static occlusal parameters: centre of occlusal force, asymmetry index of maximum occlusal force and occlusion time. These results were compared between groups, data related to patients’ complaints and clinical symptoms. The analysis was carried out using Mann-Whitney U, Kruskal-Wallis and Chi-square tests. Results. Averages of the centre of occlusal force in TMD subjects were 6.55 ± 0.99 mm, in the control group – 5.88 ± 0.69 mm; the asymmetry index of maximum occlusal force averages: 15.90 ± 2.71 and 12.93 ± 1.88; occlusion time: 0.281 ± 0.036 s and 0.236 ± 0.022 s, respectively. There were no statistically significant differences between two groups but they were found in the centre of occlusal force and the asymmetry index in the two groups (p < 0.05). Conclusions. There exists a relation between complaints of patients with TMD and static occlusion parameters. Values of the centre of the occlusal force distance and the asymmetry index of occlusal force in TMD patients with pain in the temporomandibular joint (TMJ) were significantly higher than in the control group.

Background. The aetiology of temporomandibular joint disorders (TMD) is multifactorial, whereas occlusal disharmony is one of the predisposing factors. Researchers still discuss the relation between occlusion and TMD. Objective. The study aims to investigate the relation between static occlusal parameters and TMD clinical symptoms using T-Scan II analysis system. Material and methods. The sample consisted of 44 persons divided into the treatment group of 20 TMD patients and the control group of 24 subjects without TMD. The main task of T-Scan II computerized occlusal analysis system was to record every patient's occlusion and estimate static occlusal parameters: centre of occlusal force, asymmetry index of maximum occlusal force and occlusion time. These results were compared between groups, data related to patients' complaints and clinical symptoms. The analysis was carried out using Mann-Whitney U, Kruskal-Wallis and Chi-square tests. Results. Averages of the centre of occlusal force in TMD subjects were 6.55 ± 0.99 mm, in the control group - 5.88 ± 0.69 mm; the asymmetry index of maximum occlusal force averages: 15.90 ± 2.71 and 12.93 ± 1.88; occlusion time: 0.281 ± 0.036 s and 0.236 ± 0.022 s, respectively. There were no statistically significant differences between two groups but they were found in the centre of occlusal force and the asymmetry index in the two groups (p < 0.05). Conclusions. There exists a relation between complaints of patients with TMD and static occlusion parameters. Values of the centre of the occlusal force distance and the asymmetry index of occlusal force in TMD patients with pain in the temporomandibular joint (TMJ) were significantly higher than in the control group. [ABSTRACT FROM AUTHOR]

Introduction: Angle and internal position of lateral pterygoid muscle leads to contraction over two half of the mandible in maximum opening and protrusion position so it can affects impression prosthetic procedures. The aim of this study was to evaluate the mandibular flexure in two transverse and antro-posterior dimensions. Methods: Seventy edentulous patients at Mashhad Faculty of Dentistry as the main group and 50 dentulous patients as the control group were selected. In these patients, transverse dimensions between second molar areas and also canine eminence from one side to another side, and longitudinal dimensions based on the distance between canine to second molar area at centric occlusion and maximum mouth opening were measured. Dimensional differences as the mandibular flexure were measured. Results: The mandibular dimensions in maximum opening and closed mouth were different. Average reduction in transverse dimension on second molar region at maximum mouth opening and closing position were almost equal to -0.0787 mm for target group and 0.7512 mm for control group. On anterior side, averages of these changes were equal to 0.3069 mm for target group and were 0.2254 mm for control group. Conclusion: Transverse dimensions in anterior region at maximum opening position are smaller than the same dimension at closed mouth in edentulous and dentulous patients.

Introduction: Angle and internal position of lateral pterygoid muscle leads to contraction over two half of the mandible in maximum opening and protrusion position so it can affects impression prosthetic procedures. The aim of this study was to evaluate the mandibular flexure in two transverse and antro-posterior dimensions. Methods: Seventy edentulous patients at Mashhad Faculty of Dentistry as the main group and 50 dentulous patients as the control group were selected. In these patients, transverse dimensions between second molar areas and also canine eminence from one side to another side, and longitudinal dimensions based on the distance between canine to second molar area at centric occlusion and maximum mouth opening were measured. Dimensional differences as the mandibular flexure were measured. Results: The mandibular dimensions in maximum opening and closed mouth were different. Average reduction in transverse dimension on second molar region at maximum mouth opening and closing position were almost equal to -0.0787 mm for target group and 0.7512 mm for control group. On anterior side, averages of these changes were equal to 0.3069 mm for target group and were 0.2254 mm for control group. Conclusion: Transverse dimensions in anterior region at maximum opening position are smaller than the same dimension at closed mouth in edentulous and dentulous patients.

PURPOSE. This study aims to investigate the effects of four different lateral occlusion schemes and different excursions on peri-implant strains of a maxillary canine implant. MATERIALS AND METHODS. Four metal crowns with different occlusion schemes were attached to an implant in the maxillary canine region of a resin model. The included schemes were canine-guided (CG) occlusion, group function (GF) occlusion, long centric (LC) occlusion, and implant-protected (IP) occlusion. Each crown was loaded in three sites that correspond to maximal intercuspation (MI), 1 mm excursion, and 2 mm excursion. A load of 140 N was applied on each site and was repeated 10 times. The peri-implant strain was recorded by a rosette strain gauge that was attached on the resin model buccal to the implant. For each loading condition, the maximum shear strain value was calculated. RESULTS. The different schemes and excursive positions had impact on the peri-implant strains. At MI and 1 mm positions, the GF had the least strains, followed by IP, CG, and LC. At 2 mm, the least strains were associated with GF, followed by CG, LC, and IP. However, regardless of the occlusion scheme, as the excursion increases, a linear increase of peri-implant strains was detected. CONCLUSION. The peri-implant strain is susceptible to occlusal factors. The eccentric location appears to be more influential on peri-implant strains than the occlusion scheme. Therefore, adopting an occlusion scheme that can reduce the occurrence of occlusal contacts laterally may be beneficial in reducing peri-implant strains. [ABSTRACT FROM AUTHOR]

The aim of this study was to generate normative data about condylar positions and condyle-disc relationship in healthy individuals, and to compare condylar po -sitions on Magnetic Resonance Images (MRI) to articulator generated condylar positions measured with the SAM® Mandibular Position Indicator (MP!) regarding the difference between condylar positions in centric relation (CR) and maximum intercuspation (MI). The study group consisted of 30 subjects with normal occlusion and clinically healthy temporomandibular joints. Centric occlusion-maximum intercuspation differences were recorded using the SAM® MPI. Subsequent MR images were taken with the mandible in CR and MI, and the difference in condylar position compared to the MPI findings of the same subjects. MRI and MPI data of the same individuals did not coincide (antero-posterior: p=0.000; vertical: p=0.007), and condyles were concentric in 73% and 87% for right and left sides respectively.

Aim and Objective: To evaluate and compare the position of the tongue from rest to centric occlusion in subjects with skeletal class II division 1 and skeletal class II division 2 malocclusions with subjects of skeletal class II normal occlusion., Material and Methods: The study was conducted on 30 individuals equally divided into three groups of skeletal class II division (div) 1, skeletal class II div 2, and skeletal class I normal occlusion. The study was conducted on two lateral cephalograms for each subject: one taken at rest and one in centric occlusion., Results: On evaluation of tongue posture, a statistically significant difference was observed at the middle portion of the tongue in class II div 1 malocclusion, and at the posteromedial portion of the dorsum of the tongue in class II div 2 skeletal malocclusions as the tongue moved from rest to centric occlusion. While statistically significant differences were found between class II div 2 malocclusion and class I normal occlusion, no statistically significant differences were observed between class II div 1 and class II div 2 malocclusions., Conclusion: Tongue position was observed to be the same in both class II div 1 and class II div 2 malocclusions, with no statistically significant differences. However, a great change was seen in the tongue position from rest to centric occlusion., Competing Interests: There are no conflicts of interest., (Copyright: © 2023 Journal of Orthodontic Science.)

Temporomandibular joint (TMJ) forms an integral functional part of stomatognathic system. Position, shape, structure and function of teeth have an influence on the proper functioning and health of TMJ. But a problem associated with TMJ is often neglected, and treatment for it is mostly restricted to palliative therapy. A proper understanding of the underlying cause of temporomandibular joint disorder (TMD) is necessary to device a proper treatment plan. Etiology of TMDs varies from idiopathic reasons to systemic disorders. The option of Gnathological splint is a conservative, safe and an effective mode of therapy for TMDs caused by occlusal discrepancies (fulcrum/interferences). This article presents a case report of a patient with TMD caused by occlusal discrepancy. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this in vivo study was to investigate how reproducible individuals find their habitual intercuspation. Methods: A new type of highly accurate measuring procedure was involved using an intraoral optical scanning device (Cerec Bluecam). First, a pilot test investigated the accuracy of the procedure within a standardized setting. With regard to the in vivo study, fifteen participants with full dentition were selected. For each of these individuals, eight scans were taken both in the morning and in the afternoon. Furthermore, during each session, scans were taken both in horizontal and upright position. In order to compare this to ubiquitous used processes, plaster replicas of five individuals were investigated as well. The scans were analysed, and the differences in the position of the lower jaw were calculated by a specialized superimposition program (n = 570 comparisons/OraCheck). Results: The results showed that there was no significant difference between the time of day and the position of the patient. The overall mean ± SD value for locating the habitual intercuspation was 42 ± 34 μm, however ranging from 22 ± 9 μm to 77 ± 58 μm for single individuals. On the other hand, the differences in positioning plaster replicas reached a mean of 135 ± 77 μm. Conclusions: The reproducibility of the habitual intercuspation can be obtained under in vivo conditions by a newly developed and highly accurate measuring procedure. Individuals with full dentition show values in average of 42 μm. Clinical significance: Determining the occlusal jaw relation is an important precondition in restorative dentistry and many methods are proposed for a proper occlusal registration. Although much is known about in vitro accuracy of these techniques, little is known how reproducible the habitual occlusal position itself is found between individuals. [ABSTRACT FROM AUTHOR]

Abstract: Dental arch reconstructions present as much of a challenge in paleoanthropology as in orthodontics and maxillo-facial surgery. Dentists and dental technicians know that it is very difficult to find the precise physiological crown positions that will yield individually correct occlusal kinematics in living individuals, and this difficulty is compounded by damage and deformation in fossil specimens. Typically, dental arch reconstructions of fossils are not validated, although a functionally correct reconstruction is of undoubted importance for accurate morphological descriptions and comparative studies of fossil dentitions. Here we describe a new method for functional dental arch reconstruction derived from detailed wear facet mapping (Occlusal Fingerprint Analysis, OFA) and dental-technical approaches. OFA was used to restore the entire dental arches of the most complete late Miocene fossil great ape dentition, that of Rudapithecus hungaricus, from Rudabánya in Hungary. Dental stone casts of the maxillary and mandibular dentition were repositioned in a dental articulator. The correct alignment of the tooth crowns was monitored by physically and virtually testing the tooth contacts during occlusal movements. The characteristic distribution pattern of the individual macrowear facets strongly constrains the antagonistic crown relationships in the Rudabánya specimen. We propose that the method used to reconstruct the functional dental arches of R. hungaricus, derived from kinematic evidence encoded in macrowear patterns, can be used as a reliable foundation for dental and facial restorations in fossils, and for individual occlusal crown morphology and dental arch reconstructions in modern dentistry and prosthetics. [Copyright &y& Elsevier]

In the field of craniomaxillofacial (CMF) surgery, surgical planning can be performed on composite 3-D models that are generated by merging a computerized tomography scan with digital dental models. Digital dental models can be generated by scanning the surfaces of plaster dental models or dental impressions with a high-resolution laser scanner. During the planning process, one of the essential steps is to reestablish the dental occlusion. Unfortunately, this task is time-consuming and often inaccurate. This paper presents a new approach to automatically and efficiently reestablish dental occlusion. It includes two steps. The first step is to initially position the models based on dental curves and a point matching technique. The second step is to reposition the models to the final desired occlusion based on iterative surface- based minimum distance mapping with collision constraints. With linearization of rotation matrix, the alignment is modeled by solving quadratic programming. The simulation was completed on 12 sets of digital dental models. Two sets of dental models were partially edentulous, and another two sets have first premolar extractions for orthodontic treatment. Two validation methods were applied to the articulated models. The results show that using our method, the dental models can be successfully articulated with a small degree of deviations from the occlusion achieved with the gold-standard method. [ABSTRACT FROM AUTHOR]

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For nearly a century, the diversity of concepts about ‘normal’ and ‘ideal’ dental occlusal relationships has led to confusion in trying to describe the occlusion of any individual patient. In addition, a similar controversy arises when trying to formulate treatment plans for patients who need extensive dental restorations or orthodontic treatment. And finally, the application of occlusal concepts to patients with temporomandibular pain and dysfunction has created a third area of debate. Over the past few decades, however, an appreciable part of the tenacious dogmatic heritage of this topic has been challenged. As a result, the acceptance of morphological and functional variability of the stomatognathic system has gained increasing support, and this change has important consequences for modern dental practice. In this article, the past, present and future of the subject of occlusion will be considered. [ABSTRACT FROM AUTHOR]

The aim was to compare normal overjet versus large overjet cases with clinically healthy temporomandibular joints (TMJ); to establish normative data regarding the difference between condylar positions in centric occlusion (CO) and maximum intercuspation (MI) and deflective CO contacts. Two study groups of normal overjet and large overjet cases consisted each of 33 subjects with no detectable clinical signs of temporomandibular disorder (TMD). CO-MI differences were recorded using the SAM® Mandibular Position Indicator. Deflective contacts were examined on models mounted in CO. There was a significant difference between groups in the vertical ( P = 0·030) and transverse ( P = 0·008) range of movement from CO to MI, but not in the antero-posterior direction. There were no differences in the location of deflective contacts. Results of this study showed that patients with increased overjet show some differences compared with normal overjet patients, even in the non-patients. Further research on TMD patients is needed to find out about the role these features play in the aetiology and treatment of temporomandibular disorder (TMD). This study indicates that the clinician should be paying special attention to the TMJ status of patients with a large overjet. [ABSTRACT FROM AUTHOR]

Purpose To develop an easy-to-use, dentition planning method which is based on three-dimensional (3D) computer planning technology to replace conventional plaster-cast occlusion planning techniques. Methods The optimal dental occlusion is defined according to the condition of centric occlusion, i.e. after bringing occlusal surfaces of mandibular and opposing maxillary arches into identical 3D position. This identical position of occlusal surfaces represents the common reference frame for the 3D manipulation of all graphical elements. The planning procedure involves the following steps: (1) the optimal occlusal surface is approximated as triangle and localized both on the maxilla and mandible; (2) the original volumetric model is resampled according to the occlusal orientations; (3) the program reads in the models of ideal upper and lower dental arches from files, reshapes those to the patient anatomy and visualizes the local alignment on separate panels for mesiodistal and faciolingual inclinations. The final goal of the proposed method is to combine the requirements of functional and aesthetic designs and create an input for orthodontics, implantology and maxillofacial surgery. Results In the present study the optimal dental occlusion is created by image resampling after bringing the occlusal surfaces of mandibular and opposing maxillary arches into identical 3D position. This identical position of occlusal surfaces represents the common reference frame for manipulation of all graphical elements. Conclusions The proposed graphical environment was able to fit the elements of the ideal dentition curve to patient computed tomography under predefined centric occlusion. Rotation and scaling transformations of teeth were possible in the reformatted volumetric views about any of the axes of the teeth’s own reference space. [ABSTRACT FROM AUTHOR]

An interactive software module has been developed which can be used for 3D alignment of a graphical model of upper and lower dental arches. Using this module, special tools have been implemented for functional planning of dentition which can be compared to the CT image sequence of patients to create personalized results. The alignment procedure is made under the condition of centric occlusion, i.e., after bringing occlusal surfaces of mandibular and opposing maxillary arches into identical 3D position. The occlusal surfaces are approximated by triangles and used to build up the dentition curves around them. The presented procedure for dentition planning together with the implant positioning may serve as a flexible tool for image-guided prosthesis design. The involvement of function-related principles in dentition planning adds new optimization strategies in computer-assisted insertion of implants. [Copyright &y& Elsevier]

The literature directly and indirectly related to centric relation (CR) has been reviewed chronologically. More than 300 papers and quoted sections of books have been divided into three sections. The first two parts are related to CR. Studies in this group mainly compared, either the position of the mandibular condyle or the mandible itself in different CR recordings. Various tools were discussed for this purpose. The third part of the paper is about CR–centric occlusion (CO) discrepancy. CR still remains one of the controversial issues in prosthodontics and orthodontics. Debates such as mounting casts on the articulator by reproducible records for orthodontic treatment planning and end results, and whether or not orthodontic treatment based on CO causes TMJ dysfunction, remain unsolved. The references are listed at the end of Part III. [ABSTRACT FROM AUTHOR]