Posterior Occlusal Support Research Articles

Three-Dimensional Analysis of Age and Eichner Index-Related Volumetric Changes in Mandibular Condyles

Objective: The impact of condyle volume is influenced by the presence of posterior occlusal support and age. This study aimed to retrospectively explore how age, Eichner index, and gender influence condyle volume in three dimensions, through the classification of occlusal support using the Eichner index. Material and Methods: Cone-beam computed tomography (CBCT) images of 232 patients (107 males and 125 females) aged 18-76 years were retrospectively analysed. ITK-SNAP open-source software was utilized to measure volume of condyles with semi-automated segmentation. CBCT images were analyzed based on age, gender, and the status of posterior occlusal support. Posterior occlusal support status was assessed by categorizing it into three groups according to the Eichner index: A) indicating no loss of posterior occlusal support; B) representing one to three units of occlusal support loss; and C) denoting four units of posterior occlusal support loss. For normality, Kolmogorov Smirnov test was performed and Pearson test was used to determine the correlations of continuous variables. Student's t test was used to investigate the difference between age and gender, and paired t test was used to evaluate the difference between left and right volume. P < 0.05 was considered significant. Results: There was no statistically significant difference between the mean right and left condyle volume (p > 0.05). The mean condyle volume was higher in males than females, but this difference was not statistically significant (p > 0.05). A statistically significant negative correlation was detected between age and condyle volume (p < 0.05). Age and Eichner index were statistically significantly positively correlated (p < 0.05). A statistically significant negative correlation was determined between condyle volume and Eichner index (p < 0.05). Conclusion: Volumetric measurement of the condyles using CBCT and comparison with Eichner index is crucial to assess abnormalities and bony changes affecting the TMJ in association with occlusal support and to examine and prevent complications. Although it was found that the condyle volume decreased significantly with increasing age and decreasing occlusal support, no significant difference was revealed between genders in the present study.

Association between posterior occlusal support and tooth loss in a population-based cohort: The OHSAKA study

ObjectivesThis study aimed to assess the association between posterior occlusal support (POS) and the risk of tooth loss in older adults aged ≥75 years. MethodsThis longitudinal study analyzed 94,422 participants who participated in multiple dental check-ups provided as part of the public healthcare services in Osaka, Japan, from 2018 to 2022. The participants were categorized into nine groups (A1–3, B1–4, and C1 and C2) according to their POS status using the Eichner index at baseline. The dental charts were compared between the initial and final assessments to assess tooth loss. Logistic regression analysis was used to examine the association between POS status and tooth loss, adjusted for several covariates, including age, sex, body mass index, periodontal status, oral hygiene, history of diabetes, history of hypertension, attendance at the annual dental check-up, and observational period. Furthermore, stratified logistic regression analyses were conducted using anterior or posterior tooth loss. ResultsAfter controlling for confounders, POS status was associated with tooth loss. The odds ratios (ORs) with A1 as the reference were 1.74 in A2, 2.55 in A3, 3.40 in B1, 4.74 in B2, 5.79 in B3, 6.00 in B4, 4.44 in C1, and 3.00 in C2, respectively. The ORs for anterior tooth loss were higher than those for posterior tooth loss, with the highest OR observed in B4 (21.4). ConclusionsThis large population-based cohort study showed that a decreased POS was a risk indicator for tooth loss; furthermore, the risk increased even further in the anterior teeth region.

Association of tooth location, occlusal support and chewing ability with cognitive decline and incident dementia.

Emerging evidence suggests association of tooth loss with impaired cognition. However, the differential effects of anterior versus posterior tooth loss, occlusal support loss and chewing ability are not considered comprehensively. We conducted cross-sectional (N = 4036) and longitudinal analyses (N = 2787) on data from Health 2000 and 2011 Surveys for associations of posterior occlusal support loss, anterior versus posterior tooth loss, and chewing ability with baseline cognition and 11-year cognitive decline. Additionally, 15-year incident dementia risk was investigated (N = 4073). After considering relevant confounders and potential reverse causality bias, posterior occlusal support loss significantly increased dementia risk across all categories indicative of posterior occlusal support loss (hazard ratios [HRs] between 1.99 and 2.89). Bilateral inadequate posterior occlusal support was associated with 11-year decline in overall cognition (odds ratio [OR] = 1.48:1.00-2.19), and unilateral inadequate posterior occlusal support with total immediate (OR = 1.62:1.14-2.30) and delayed recall decline (OR = 1.45:1.03-2.05). Moreover, posterior tooth loss was associated with dementia (HR = 2.23:1.27-3.91) and chewing ability with total immediate decline (OR = 1.80:1.04-3.13). Posterior tooth and occlusal support loss significantly increases dementia risk. The impact of posterior occlusal support loss appears to be dose-dependent, and this effect is distinct from that of dentures. Dental healthcare services should be particularly attentive to the state of posterior dentition. Further studies exploring possible mechanisms are warranted.

The relationship between changes in occlusal support and masticatory performance using 6-year longitudinal data from the SONIC study

ObjectivesReduced occlusal support is thought to be related to a decline in masticatory performance. However, previous research in this field was based on cross-sectional studies. In this study, we conducted a 6-year longitudinal observation of older adults living in the community and examined the associations of changes in occlusal support with masticatory performance. MethodsOf the 864 participants aged 72–74 years in the SONIC study, 488 who were followed up (median follow-up period 5.92 years) and had no missing data were included in this study. Participants were divided into three groups according to the number of occlusal support zones in the posterior area: Complete occlusion (four zones), Reduced occlusion (one to three zones), and Collapsed occlusion (no occlusal support zone). Longitudinal analysis of the relationship between occlusal support and masticatory performance was undertaken with linear mixed‐effects models. ResultsSex, occlusal force, number of unreplaced missing teeth, aging, and occlusal support change were significantly related to masticatory performance. Furthermore, the interaction term between change in occlusal support and aging was a significant explanatory variable for the decline in masticatory performance. The interaction was strongest in the group that changed from Complete or Reduced occlusion to Collapsed occlusion. This result indicates that the loss of occlusal support is a major factor contributing to declining masticatory performance. ConclusionsThe decline of occlusal support was greatly associated with the deterioration of masticatory performance. Our results suggest that older adults need to prevent the collapse of posterior occlusal support to maintain their masticatory performance. Clinical significanceOcclusal support is important for preserving masticatory performance in older adults. Preventing the loss of molars and retaining occlusal support may contribute to maintaining food intake diversity and nutritional status, thereby improving quality of life. Dental professionals need to carefully examine dental status to assess the risk of occlusal collapse.

Assessment of subjective and objective masticatory function among elderly individuals with mild cognitive impairment

BackgroundMasticatory function is known to be related to cognitive ability; therefore, factors for improving masticatory function should be identified.AimsThis study aimed to identify factors influencing masticatory function associated with mild cognitive impairment (MCI) in elderly individuals.MethodsA total of 123 elderly participants [mean age: 76.5 ± 6.5 years; 82 females (66.7%), 41 males (33.3%)] were included. Cognitive function was evaluated by the Korean version of the Mini-Mental State Examination (KMMSE). Questionnaires for subjective evaluation were administered, and dynamic objective masticatory function evaluations, including chewing tests and bite force measurements, were performed. Intergroup differences were evaluated by the Wilcoxon rank-sum and chi-square test, and correlations between cognitive ability and masticatory function were evaluated by multilinear logistic regression.ResultsThe number of teeth, number of posterior teeth, bite force, masticatory ability index (MAI) and posterior support status showed significant differences between the normal (KMMSE > 23) and MCI (KMMSE ≤ 23) groups. However, only the MAI, representing dynamic masticatory performance, was significantly associated with MCI regardless of age, sex and removable prostheses. The number of teeth and posterior teeth, bite force, subjective masticatory ability and posterior occlusal support showed no significant association with MCI.DiscussionThese results suggested the importance of chewing function for preventing the progression of cognitive impairment.ConclusionsConsidering that only the MAI was significantly associated with MCI, it is more important to improve chewing efficiency by harmonizing therapeutic prosthetics with the surrounding masticatory system than simply increasing the number of teeth to prevent or delay cognitive impairment in elderly individuals.

The Association of Dietary Intake, Oral Health, and Blood Pressure in Older Adults: A Cross-Sectional Observational Study.

Hypertension is related to impaired mastication that causes malnutrition, declining the general health of older adults. This study assessed the role of dietary intake in the relationship between oral health and blood pressure. Eight hundred ninety-four adults aged ≥65 years who independently lived in rural regions of Japan participated in this study. Hypertension was classified according to the guidelines of the Japanese Society of Hypertension. The oral condition was evaluated by analyzing the remaining teeth, occlusal force, posterior occlusal support, masticatory performance, oral moisture, and oral bacterial level. Dietary intake was assessed using a brief self-administered dietary history questionnaire. Mann-Whitney U, chi-square, Kruskal-Wallis tests, and logistic regression analyses were used to elucidate the factors related to hypertension. Normotensive, hypertensive, and history of hypertension were observed in 30.9%, 23.8%, and 45.3% of the participants, respectively. The factors significantly associated with the hypertension were age, body mass index, posterior occlusal support condition, and sodium-to-potassium ratio related to salt intake and/or vegetable intake. Participants without posterior occlusion significantly had higher risk of hypertension (odds ratio = 1.72). This study suggested that there was an association between oral health and hypertension, while the loss of occlusal support may influence nutritional intake conditions.

Full mouth rehabilitation through re-establishment of occlusal plane in partially edentulous patient with reduced vertical dimension accompanied by loss of posterior occlusal support

Full mouth rehabilitation through re-establishment of occlusal plane in partially edentulous patient with reduced vertical dimension accompanied by loss of posterior occlusal support

Dental Occlusion: Proposal for a Classification to Guide Occlusal Analysis and Optimize Research Protocols

Dental occlusion often rhymes with confusion, discrediting many research protocols. The profession seems to be in "major chaos about occlusion." This may be due to the lack of a precise classification of occlusal dysfunctions. We suggest using a classification based on the separation of three occlusal functions, with the identification of precise, objective clinical diagnostic criteria. This article aims to define a precise classification of occlusal functions, in order to be able to establish a positive diagnosis of occlusal disorders. This occlusal analysis method could then be used in the daily practice of dentists and orthodontists, with a view to align epidemiological studies that focus on occlusion, in order to obtain results capable of comparison in different studies. A analysis of the literature in PubMed database published between the early 1970s and the present day identified many confusing definitions of occlusal disorders. In this paper, we propose the separation of occlusal functions into three subcategories: Stabilizing, centering, and guiding functions, defining three different subcategories of occlusal disorder. Occlusal function allows the definition of three kinds of malocclusion: Stabilizing dysfunction, centering dysfunction, and guiding dysfunction. The individualization of clear subcategories could allow the study of the more pertinent impacts of pathogenic malocclusion. This classification of occlusal functions or dysfunctions allows lines to be drawn between different occlusal situations that are frequently confused, such as a loss of posterior occlusal support and loss of occlusal vertical dimension, infra-occlusion and loss of posterior support, short or reduced dental arch, reversed and scissor occlusion, sagittally and transversely deflected mandible, posterior occlusal interference and balancing contact, as well as natural and iatrogenic malocclusion. An occlusal analysis that makes use of the three occlusal functions, "stabilizing, centering, guiding," could offer diagnostic standardization. It may also allow the avoidance of incorrect interpretations. Therefore, this occlusal function classification may be relevant to many fields, for instance, for epidemiological studies of occlusion and the periodontium, TMD and occlusion, or TMD and orthodontic treatment.

Factors affecting the oral health of inpatients with advanced cancer in palliative care

PurposePatients with terminal cancer undergoing multidisciplinary palliative care often have oral health problems, but these details are still unclear. This cross-sectional study aimed to elucidate the oral health of patients with terminal-stage cancer who are inpatient recipients of acute-phase palliative care, and to unveil the factors affecting their oral health.MethodsParticipants were 121 patients with terminal-stage cancer (68 males, 53 females, mean age: 73.6 ± 11.1 years) and oral health complaints. They received palliative care at Tokyo Medical and Dental University Medical Hospital between April 2017 and August 2019. Their demographic and medical details were extracted, retrospectively, from their medical records, and their oral health status, such as the number of natural teeth, removable denture usage, Oral Health Assessment Tool (OHAT), and Dysphagia Severity Scale, were evaluated. All outcomes were assessed by a dentist from the palliative care team.ResultsThe problems with soft tissue, saliva, and oral cleanliness were observed. The absence of posterior occlusal support was common, and the use of removable dentures was often inadequate. In contrast, swallowing function was relatively well-conserved and 46.3% of the participants were capable of nutrition intake solely by mouth. Multiple regression analysis revealed a significant association between total OHAT score and age, consciousness level, prognostic level, and method of nutritional intake.ConclusionThe results revealed that the oral health of terminal cancer patients under palliative care declined despite receiving routine oral care from nurses, and suggest the importance of including dental professionals in multidisciplinary palliative care.

The impact of occlusal support on temporomandibular disorders: a literature review

Temporomandibular disorders are a multifactorial disease. Occlusal support and the number of teeth in dentition have significant effects on the masticatory system. The current study aims to review the role of occlusal support in association with findings of temporomandibular disorders. Data sources were PubMed, Web of Science and Google Scholar, with 1411 citations published over the period 1992–2019. The selection criteria stipulated that articles must have reported the association between the number of teeth, occlusal unit, occlusal support and temporomandibular disorders. A total of 15 full-text articles was finally accessed for eligibility in the current review. The studies on temporomandibular disorders were collected from various sources, including articles reporting temporomandibular disorder symptoms ( n=1), temporomandibular disorder signs ( n=5), temporomandibular joint osseous changes ( n=1), temporomandibular joint dysfunction using the Helkimo index ( n=2), and temporomandibular disorder classification ( n=6). Of these articles, significant associations were found between: the number of missing teeth and temporomandibular disorders ( n=5); the number of occlusal units and occlusal supports and temporomandibular disorders ( n=3); the position of the lost occlusal units and temporomandibular disorders ( n=1). Loss of the occlusal unit has more impact on temporomandibular disorders than the loss of posterior teeth. The total loss of unilateral occlusal support seems to be an aetiological factor for temporomandibular disorders, and maintenance of balanced posterior occlusal support has a role in the prevention and management of temporomandibular disorders.

Oral health status and its association with nutritional support in malnourished patients hospitalised in acute care

This cross-sectional study aimed to examine the oral health of malnourished acute-care hospital inpatients, who were the subjects of a nutritional support team (NST). We also aimed to elucidate the systemic and nutritional factors associated with the oral health of those patients. Interventions by NST are essential for inpatient nutrition management and require the active participation of dental professionals. However, information is limited regarding the state of oral health among acute-stage malnourished inpatients. We enrolled 255 hospitalised patients (101 women, mean age: 69.7±14.4years) who were referred to an NST for nutrition management between April 2016 and July 2019. The main outcome was the Oral Health Assessment Tool (OHAT) scores. Moreover, we assessed participants' demographic characteristics, nutritional status, number of natural and functional teeth, posterior occlusal support, denture use, Dysphagia Severity Scale, whether oral health management was needed, and the methods of nutrition intake. Several participants presented with a deteriorated oral health. Consequently, oral health management was often regarded necessary in these patients. Approximately half were fed by parenteral or tube feeding. Multiple regression analysis revealed the OHAT score has a positive association with age (P=.008), and a negative association with body mass index (P=.009) and the method of nutrition intake (P=.028). Malnourished inpatients at an acute care hospital who were subject to an NST had a deteriorated oral health status. Additionally, poor oral health was associated with poor nutritional status and nutrition intake methods.

The Significance of Posterior Occlusal Support of Teeth and Removable Prostheses in Oral Functions and Standing Motion.

The purpose of this study was to evaluate the effect of posterior occlusal support of natural teeth and artificial teeth on oral functions and standing motion. Patients who had been treated with removable prostheses were enrolled as the subjects. Their systemic conditions (body mass index (BMI) and skeletal muscle mass index (SMI)) were recorded. The subjects were classified into two groups according to a modified Eichner index: B1–3 (with posterior occlusal support) and B4C (without posterior occlusal support). Maximum occlusal force (MOF), masticatory performance (MP), and standing motion (sway and strength) were evaluated for cases with and without removable prostheses. There were no significant differences in BMI and SMI between the B1–3 group and the B4C group. The subjects with removable prostheses demonstrated significantly higher values in MOF, MP, and sway and strength than the subjects without removable prostheses. The comparison of oral functions between the B1–3 group and the B4C group revealed that the positive effect of posterior occlusal support of natural teeth and removable prostheses and the significant positive effects of posterior occlusal support on standing motion were partly observed in these comparisons. Posterior occlusal support of natural teeth and even of removable prostheses may contribute to the enhancement of oral functions and standing motion.

Immediate Rehabilitation of the Severely Atrophic Maxilla Using Trans-Sinus Nasal Protocol and Extended Length Subcrestal Angulated Implants. Case Series With 1-Year Follow-Up.

Immediate fixed full-arch rehabilitation of the severely atrophic maxilla eliminates use of a tissue-supported prosthesis during the healing phase and maximizes patient comfort and quality of life. The surgical treatment options available for immediate rehabilitation of the severely atrophic maxilla are dependent on the location and availability of the residual alveolar ridge. When bone is only available in the intercanine region, a graftless approach using tilted distal implants may not provide adequate distance between implants for favorable biomechanics. Subsequently, zygomatic implants are the alternative to provide adequate posterior occlusal support. Use of extended length subcrestal angulated implants offers an additional implant option for the clinician to restore the severely atrophic maxilla immediately. The treatment protocol involves anchorage of the implant fixture to the lateral wall of the nasal bone. The distally tilted implant transverses an augmented sinus cavity and extends to the site of the first permanent molar. The novel implant subcrestal angulation and use of a multi-unit abutment promotes passivity of fit of a full-arch fixed immediate prosthesis. Five clinical case reports from private practice are presented that outline the clinical value of the novel implant design in the rehabilitation of the severely atrophic maxilla. In each case, the use of zygomatic implants would be the only alternative to provide an immediate fixed prosthesis due to the absence of residual alveolar bone in the maxilla premolar and molar regions. The use of extended-length subcrestal angulated (ELSA) implants with straight or angulated multiunit abutments have successfully restored the maxillary arch immediately.

Association between the dental occlusion and perceived ability to eat foods of Taiwanese older adults.

Tooth loss is a common problem among older adults that affects masticatory function (MF) and food selection. Financial burden is a reason that some older adults in Taiwan with this condition forgo dental restoration. To identify the number of posterior occlusal support areas (POSAs) associated with MF. Large-scale cross-sectional study included 1100 community-dwelling participants of Taiwan aged ≥65years. Participants completed dental examination and questionnaires through personal interviews. Masticatory performance was evaluated using a colour-changeable chewing gum. Masticatory ability was evaluated on the basis of how many of 14 common foods the participants were able to eat. Participants were grouped into 10 categories (A1-A3, B1-B4 and C1-C3) according to the Eichner index (EI) of posterior occlusal contacts. Multivariable regression models were used to analyse the association between the EI groups and MF. More than 80% of the participants with two or more POSAs (those in groups A1-B2) could easily eat various foods. Compared with those in groups A1-B2, those in groups in B3, B4, C1, C2 and C3 exhibited a significantly different masticatory performance (all P<.001) and significantly higher difficulty in eating fruits and vegetables. A dose-response effect between POSAs and perceived masticatory ability to eat fruits and vegetables was observed (P<.05 for both trends). Preservation of at least two POSAs is essential for MF. Older adults with tooth loss can undergo the restoration of two POSAs to improve MF and increase food intake.

Relationship Between Oral Health and Fractures in Community-Dwelling Older Japanese Adults

ObjectiveTo investigate the relationship between poor oral health and the incidence of fall-related fractures in older Japanese individuals. DesignA 9-year prospective cohort study. Setting and ParticipantsParticipants comprised 937 community-dwelling older Japanese adults aged 70 years or older. They all lived in the Tsurugaya district, a suburban area of Sendai city, and underwent comprehensive geriatric assessment, including an oral examination, in a public facility. MeasurementsThe exposure variables were related to oral health status (posterior occlusal support, number of remaining teeth, and occlusal force). The outcome measure was the incidence of fall-related fractures, which was determined by National Health Insurance data. Analyzed covariates included age, sex, medical history, smoking, alcohol drinking, educational level, depressive symptoms, cognitive impairment, physical function, body mass index, and history of falls. Statistical relationships were examined by calculating hazard ratios (HRs) at 95% confidence intervals (CIs) using the Cox proportional hazard model. ResultsIn the multivariate analysis, the HRs of fall-related fractures were significantly higher in those with unilateral posterior occlusal support (HR, 2.72; 95% CI, 1.13-6.55) and no posterior occlusal support (HR, 2.58; 95% CI, 1.29-5.15) than in those with bilateral posterior occlusal support. The HRs (95% CIs) of fall-related fractures in individuals with 10-19 and 1-9 teeth and edentulous individuals were 1.77 (0.81-3.89), 2.67 (1.24-5.75), and 2.31 (1.01-5.28), respectively, compared to those with ≥20 teeth. Conclusions and ImplicationsPoor oral health status is a risk factor for the incidence of fall-related fractures in community-dwelling older Japanese individuals. The findings suggest that attention should be focused on oral health status to further understand the risk of fall-related fractures among community-dwelling older adults.

Efecto de la pérdida prematura de molares primarios sobre la relación horizontal incisiva

La pérdida prematura de molares primarios predispone a maloclusiones incluyendo apiñamiento, impactación de dientes permanentes y alteración de la relación molar y canina. El objetivo del presente estudio es determinar el efecto de las pérdidas prematuras de molares primarios sobre la relación incisiva horizontal. El estudio es documental, retrospectivo y observacional. Se evaluaron los registros ortodóncicos (historias clínicas, fotografías y radiografías) de 209 pacientes con edades entre 4 a 15 años. La relación incisiva horizontal se consideró normal (grupo 1) cuando hubo contacto entre en borde incisal del incisivo inferior con la cara palatina del superior, aumentada (grupo 2) cuando había distancia positiva entre ellos y negativa (grupo 3) cuando los bordes incisales se encontraban a tope o en mordida cruzada. Los datos se analizaron utilizando coeficiente Pearson (p?0,001). El 22% (45 pacientes) presentó pérdidas prematuras. La prevalencia de pérdidas prematuras no tuvo diferencia significativa entre géneros y fue mayor en el grupo de 7 a 9 años. De los pacientes con pérdidas prematuras, 6 (13,3%) se clasificó en el grupo 1; 12 (26,7%) en el grupo 2 y 27 (60%) en el grupo 3. Hubo asociación positiva entre el número de molares perdidos y la presencia de mordida cruzada anterior, siendo la media de molares perdidos mayor (4, 7) en el grupo 3. Se demostró que las pérdidas prematuras de molares primarios tienen una relación estadísticamente significativa con la mordida cruzada anterior, siendo posible que la falta de soporte oclusal posterior favorezca el desplazamiento protrusivo de la mandíbula.

Masticatory performance and other oral functions in community-dwelling elderly patients without posterior occlusal support by natural teeth.

To evaluate masticatory performance (MP), maximum occlusal force (MOF), maximum tongue pressure (MTP) and oral diadochokinesis (ODK) among community-dwelling elderly patients without posterior occlusal support. This study enrolled community-dwelling elderly patients (≥65 years old) who belonged to Eichner A, B4, C1, C2, and C3. Each oral function was statistically compared among groups. Correlations between MP and other variables were examined in Eichner B4 and C patients. MP and MOF values in Eichner B4 and C patients were significantly lower than in Eichner A patients. There were significant differences in MTP values between Eichner "A and C2, C3", and "B4 and C2, C3". ODK in Eichner C patients showed significantly lower values compared to Eichner A patients in general. Although there were statistically significant correlations of MP with age, the number of remaining teeth and all oral functions were identified, and multiple regression analysis indicated that MOF and MTP were independently related to MP. Oral functions in Eichner B4 and C patients were lower compared to Eichner A patients. MP was significantly correlated with MOF and MTP in elderly patients without posterior occlusal support, suggesting the importance of rehabilitation of MOF and MTP in MP.

Influence of Simulated Loss of Posterior Occlusal Support on Three-dimensional Condylar Displacement

The objective of this study was to verify whether loss of posterior occlusal support induced displacement of the mandibular condyles from a physiological point of view. Stabilization-type splints were fabricated for 12 healthy dentulous individuals. Each splint was designed to cover the bilateral maxillary teeth up to the second molars. To reproduce loss of posterior occlusal support, the extent of the splint was reduced one tooth at a time, bilaterally, starting from the back and moving forward sequentially. Tapping movement and lateral excursions were performed with each splint and a jaw movement tracking device with 6-degrees of freedom used to observe condylar displacement. Evaluation of 3-dimensional (3-D) displacement of the kinematic axis of the condyle during experimental jaw movement was performed under each occlusal condition with occlusal contact on all teeth, including the maxillary second molars. The habitual closing position was used as the reference. An increase was observed in 3-D displacement of the kinematic axis at the terminal point of the tapping movement with loss of occlusal support, and significant differences were observed in both condyles. An increase was also observed in 3-D displacement of the kinematic axis on the working side during lateral excursion with loss of occlusal support, and a statistically significant difference was observed in the left condyle. A small increase was observed in 3-D displacement of the kinematic axis on the non-working side during lateral excursion with loss of occlusal support. The results of this study suggest that loss of posterior occlusal support induces displacement of the mandibular condyles, suggesting that occlusal support in the molar region is an important factor in stabilization of the condylar position.

The impact of occluding pairs on the chewing patterns among the elderly

ObjectivesThis study aims to investigate the impact of occluding pairs (OPs) on chewing strokes, chewing time, mealtime duration, and bite force in an aging population. MethodsThe 100 participants included 52 women and 48 men with average age of 71.2 years. The subjects were restricted to those who can eat what they wanted and had no temporomandibular joint disorder (TMD) and dysphagia history; their OPs were counted in the posterior occlusal support zone in accordance with the Eichner classification. Free habitual mastication of a cornstarch cookie was analyzed by recording the number of chewing strokes and the amount of time needed for complete mastication. Strokes were counted by considering the opening and closing mandibular movements. Mealtime was defined as the time spent to finish a lunchbox and accomplish swallowing. Bite force was estimated with a T-Scan III®. A linear regression analysis was used to evaluate the impact of the OPs on the chewing strokes, chewing time, mealtime duration, and bite force. ResultsIn this study, 76% of the participants had 4 OPs and 12% participants had 3 OPs. Increasing the OPs significantly shortened the chewing time and mealtime duration (P = 0.02). The mealtime duration did not notably affect the chewing time (P = 0.237). There was significant association between OPs and bite force (P < 0.0001). ConclusionsIn elderly, increasing OPs significantly raised the bite force and shortened the chewing time and strokes. More OPs might be the key to maintain good chewing function. Clinical significanceAmong the elderly, increasing OPs significantly raised the bite force and shortened the chewing time and mealtime duration. To provide better chewing function, good oral hygiene is important to maintain as many OPs as possible; how to gain more OPs is essential concern in the prosthodontic treatment plan making.

Decrease in posterior occlusal support area can accelerate tooth loss: The Suita study.

Purpose A decrease in posterior occlusal support is considered to increase the load on remaining teeth and thus accelerate tooth loss. Therefore, a follow-up study was carried out to perform a longitudinal analysis of the association between the posterior occlusal support region and tooth loss.Methods The participants of the study were 806 Suita Study participants who underwent physical health checkups both at baseline and at follow-up. The participants were classified into three groups by posterior occlusal support area (POSA) using the Eichner Index at baseline: Perfect POSA group, Eichner A; Decreased POSA group, Eichner B1-3; and Lost POSA group, Eichner B4 and Eichner C1-2. Participants were also classified into two groups according to whether they had tooth loss during the follow-up period. Tooth loss risk factors were investigated through the construction of logistic regression models with tooth loss as the dependent variable and posterior occlusal support, sex, age, periodontal disease, stimulated salivary flow rate, smoking habit, drinking habit, denture wearing, utilization of dental services, brushing habits, diabetes mellitus, osteoporosis and number of years of follow-up as independent variables.Results In the results of the logistic regression model, the adjusted odds ratio (95%CI) for tooth loss with the Perfect POSA group as the reference was 3.19 (1.98-5.14) for the Decreased POSA group and 4.57 (1.97-10.62) for the Lost POSA group.Conclusions This study showed that decreased POSA accelerated tooth loss in the general urban population.