The International Journal of Prosthodontics, 04/2005

Purpose: Obstructive sleep apnea syndrome (OSAS) is a sleep disorder characterized by repetitive episodes of upper airway obstruction. Recently, it has been suggested that edentulism worsens sleep apnea; sleeping without dentures is associated with a significant increase in the apnea-hypopnea index. OSAS is also related to depression. The aim of this study was to assess, in a group of elderly occupants in residential homes in the Turin district of Italy, (1) the prevalence of key symptoms and indicators of OSAS and the prevalence of depressive feelings; (2) how the reduction of vertical dimension of occlusion (VDO) influenced the onset of OSAS; and (3) whether a relationship between OSAS and depression was present. Materials and Methods: The sample population consisted of 403 people (77% men, 23% women; age range, 65 to 90 years). The subjects underwent the Italian version of the Mini Mental State Examination (MMSE) to assess their mental condition. The remaining collaborating subjects completed 2 questionnaires to assess the risk of OSAS (Berlin Questionnaire) and depressive feelings (Beck Depression Inventory). Results: Of the 403 elderly residents initially evaluated with the MMSE, 97 were excluded from the study, reducing the sample size to 306 subjects (75% women, 25% men; mean age ± standard deviation, 83.12 ± 11.10 years).The analysis of these data revealed a statistically significant association between the risk for sleep apnea and the VDO (P .0001), and between sleep apnea and depressive feelings (P .05). Conclusion: This study revealed that inadequate VDO is closely associated with the risk of OSAS, and that depressive feelings are more present if there is a high risk for OSAS.

Purpose: The aim of this study was to compare the clearance of an acidic drink in patients with tooth wear caused by regurgitation erosion to that in patients without tooth wear. Materials and Methods: Oral clearance was measured using antimony electrodes at 4 soft tissue sites around the mouth in the patients with erosion caused by regurgitation and compared to a matched control group. The data were analyzed for pH at the resting state, the time below 5.5, and the lowest recorded pH. In addition, the resting hydration levels and viscosity of fluid from the minor salivary glands, the pH of resting saliva, and the flow rate and buffering capacity of stimulated saliva were compared between the 2 groups of patients. Results: The pH recorded at the tip of the tongue reached a lower level in the controls than in those in the erosive tooth wear group (P .05) and the time that the pH remained below 5.5 was longer in the controls than those with tooth wear (P .05). The flow rate from the minor salivary glands (P .05) and the viscosity of resting saliva appeared to differ between the two groups (P .001). Conclusion: Oral clearance at the tip of the tongue, measured as a function of the lowest pH reached and the time below 5.5, was quicker in those with erosive tooth wear than the controls. It is suggested that this may be a result of a feedback mechanism from constant exposure of the oral environment to low pH.

Purpose: Bruxism may increase the activity and volume of the masticatory muscles, yet its resulting effect on bite force is controversial. This study evaluated the relationship between voluntary maximal bite force (MBF) and presence of bruxism in 80 dentate young adults (40 men, 40 women, 20 to 38 years old), controlling for sex, body mass index (BMI), and presence of orofacial muscular pain during the MBF measurement. Materials and Methods: MBF was measured with a compressive load transducer at the first molar region. Information about the presence of bruxism was collected by means of self-report of centric or eccentric bruxism during the day or night and/or presence of tooth wear. Data on MBF were analyzed by analysis of covariance, with bruxism and sex as fixed factors, and BMI and orofacial muscular pain as covariates (.05 level of significance). Results: The mean ± standard deviation values of MBF were 859 ± 304 N for nonbruxers (n = 49) and 806 ± 282 N for bruxers (n = 31), with no significant difference between groups (P = .842). BMI was not a significant covariate for MBF (P = .237), and neither was the presence of orofacial muscular pain (P = .560). Sex was statistically significant for MBF (P .001), and men (1,009 ± 290 N) had higher MBF than women (668 ± 179), but there was no interaction between sex and bruxism in relation to the MBF (P = .861). Conclusion: These results suggest that bruxers and nonbruxers did not have different voluntary MBF in this sample of young dentate adults.

Purpose: The objective of this study was to determine whether elevator and depressor muscle activity during 5 minutes of mastication is affected by the presence of a prosthetic appliance in elderly patients. Materials and Methods: Thirty edentulous subjects (EG) and 30 age-matched dentate subjects (DG) were studied. Surface electromyographic (EMG) recordings were obtained from the anterior temporal muscle, masseter muscle, and the submandibular group in the region of the anterior belly of the digastric muscle on the left and right sides. Muscle activity was recorded during maximal voluntary contraction (MVC) in the intercuspal position, maximal opening (Omax), and during 5 minutes of mastication. Elevator muscle activity during mastication was expressed as a percentage of maximal muscle activity in the intercuspal position (%MVC), and depressor muscle activity was expressed as a percentage of maximal opening (%Omax). The effect of 3 factors was investigated using a mixed analysis of variance design: the factor of muscle, with 6 muscles involved; the factor of time (5 minutes of mastication); and the factor of dental status, where some participants had their own natural dentition and others had complete dentures. Results: The results revealed significant effects for the factors "muscle" and "time" (P .001 for the factor "muscle"; P .001 for the factor "time"). The time by group interaction was significant (P = .046). In the EG, muscle activity gradually decreased during the 5-minute interval of mastication, while in the DG it decreased more rapidly from the first to the third minute and then increased until the fifth minute. There was also a significant effect regarding the presence of natural teeth or complete dentures (P .034). Complete denture wearers had higher muscle activity relative to %MVC or %Omax than dentate subjects. Conclusions: Muscle activity during 5 minutes of mastication depended greatly on the presence of the prosthetic appliance, since edentulous subjects had to use higher potentials of muscle activity (%MVC or %Omax) than age-matched dentate subjects, and were unable to increase activity at the end of mastication. The difference in chewing patterns and activity between complete denture wearers and dentate subjects should be explained to patients prior to prosthetic treatment to help them adjust their expectations.

Purpose: This study assessed the duration of different phases of the chewing cycle and the height of the masticatory cycle in relation to the type of lateral guidance. Materials and Methods: Fifty-three subjects with the same type of lateral guidance on both sides were categorized into 3 groups: anterior protected articulation, canine protection, and group function. Overbite was measured clinically. Border jaw movements were recorded using a Sirognathograph, and the lateral guidance angle in the frontal plane was measured. Jaw movements during unilateral chewing of peanuts were recorded on the frontal plane using the Sirognathograph connected to an electrocardiograph used for transcription. A single masticatory cycle was divided into opening, closing, and occlusal-level phases. Masticatory parameters were analyzed by one-way analysis of variance, correlations, the paired Student t test, and multiple linear regression. Results: Women showed significantly longer total cycle duration than men. Subjects with canine protection showed the highest lateral guidance angle and the highest chewing cycle duration. Subjects with anterior protected articulation exhibited significantly longer occlusal-level phases. Fifty-nine percent of the variation in duration of the occlusal-level phase can be explained by the type of lateral dental guidance, gender, and lateral guidance angle. Only overbite was a predictor of height of mastication. Conclusion: The type of lateral guidance, gender, and frontal guidance angle are correlated with the duration of the occlusal-level phase during unilateral chewing of peanuts. The height of mastication cannot be explained by the type of lateral guidance.

Purpose: Several clinical studies suggest that psychologic factors may play an important role in the etiology and maintenance of temporomandibular disorder (TMD) signs and symptoms. The goal of this study was to verify the prevalence of anxiety and depression in adolescents, and their relationship with signs and symptoms of TMD. Materials and Methods: The sample comprised 217 nonpatient adolescents between 12 and 18 years of age. The subjective symptoms and clinical signs of TMD were evaluated, respectively, using a self-report questionnaire and the Craniomandibular Index (CMI, which has 2 subscales), the Dysfunction Index, and the Palpation Index. The Hospital Anxiety and Depression Scale (HADS), a 14-item self-administered rating scale that was developed specifically to identify anxiety and depression in nonpsychiatric medical outpatients, assessed levels of anxiety and depression. Results: In the total sample, anxiety and depression were present in 16.58% and 26.71% of subjects, respectively, including all levels of HADS. The results showed that there were positive correlations between CMI and Palpation Index and anxiety (HADSa) (P .01) but not with depression (HADSd). An association between the number of TMD subjective symptoms and HADSa/HADSd was found (P .01). Conclusion: Anxiety and depression, although of mild intensity, are common in adolescents. In this study both HADSa and HADSd were associated with an increasing number of TMD subjective symptoms. However, only anxiety was correlated with clinical signs of TMD (CMI), primarily muscle tenderness (Palpation Index).