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PubMedDate not supplied

Changes in the masticatory function of complete denture wearers after relining the mandibular denture with a soft denture liner.

PURPOSE: The purpose of this study was to examine changes in the masticatory function of complete denture wearers after relining the mandibular denture with a soft liner. MATERIALS AND METHODS: Conventional complete dentures were fabricated for 6 completely edentulous patients. One month after completing adjustments of the dentures, maximum biting force, masticatory performance, and electromyography of the masseter muscle during mastication were recorded. Chewing strokes, chewing time, muscular activity, and masticatory rhythm were calculated using the recorded electromyography. The mandibular dentures were then relined with a soft liner. One month after finishing adjustments of the relined dentures, the same tests were performed. These values were compared using a paired t test (alpha = 0.05). RESULTS: When using the soft liner, masticatory performance and maximum biting force were significantly greater (P = 0.019 and P = 0.023, respectively). In addition, the number of chewing strokes was significantly lower (P = 0.020), and chewing time was reduced (P = 0.010). A more stable masticatory rhythm was also found in the initial chewing stage. The muscular activity tended to decrease after the insertion of the lined denture, but no significant difference was found between before and after relining. CONCLUSION: It was shown that applying a soft lining material to the mandibular dentures of 6 edentulous patients improved masticatory function with no adverse effect on the muscular task.

Acrylic Resins↗
PubMedDate not supplied

Retention of a posterior resin-bonded fixed partial denture with a modified design: an in vitro study.

PURPOSE: The aim of this study was to test in vitro the resistance of a modified resin-bonded fixed partial denture (RBFPD) to detachment using a laboratory setup simulating load fatigue of mastication forces. The effect of varying the cement type was also investigated. MATERIALS AND METHODS: Extracted teeth were used to prepare specimens each consisting of a premolar and a molar with a space equivalent to a molar in between. Five test groups were prepared (n = 7). Specimens in group 1 were prepared to receive conventional RBFPDs with proximal grooves, occlusal rests, and lingual wings. Specimens in groups 2 and 3 were prepared to receive modified RBFPDs with retentive-slot restorations. Specimens in group 4 were prepared to receive RBFPDs with retentive-slot restorations only, whereas specimens in group 5 were prepared similarly to the ones in groups 2 and 3 but with inlay preparations instead of the retentive slots. Castings were made and their fit surfaces microetched. In groups 1, 2, 4, and 5 castings were cemented with Cement-It, whereas castings of group 3 were cemented with Panavia 21. Slot cavities of groups 2, 3, and 4 were restored with a resin composite. Specimens were subjected to compressive load cycling for 230,000 cycles at 4 Hz under water. Castings were then separated from the abutments under tensile loading. RESULTS: Mean separation forces were: group 1 = 361 N, group 2 = 525 N, group 3 = 562 N, group 4 = 449 N, and group 5 = 417 N. Groups 2 and 3 had significantly higher mean separation forces than groups 1 and 5. Separation of castings in groups 2 and 3 was associated with a higher frequency of cohesive fracture of the abutments than in group 1. Adhesive failure was uncommon among specimens of groups 2, 3, and 4. CONCLUSION: The modified RBFPDs of groups 2 and 3 had better potential for retention. Increased resistance to dislodgment of the modified RBFPDs was not directly related to the surface area of the castings, nor was it related to the type of resin cement, but rather to mechanical interlocking of the castings with the retentive-slot resin composite restorations.

Analysis of Variance↗
PubMed2000

Tooth wear and loss: symptomatological and rehabilitating treatments.

The authors report a clinical case that presented tooth wear and absence, with painful muscular and articular symptomatology, and also alteration in deglutition, mastication and speech. The clinical procedures used were re-establishment of vertical dimension of occlusion, mandibular centric relations, and occlusal contacts through therapeutic removable partial dentures. The condyle position was analyzed in habitual occlusion and in occlusion with dentures, through transcranial radiographs of the temporomandibular joints. Oral rehabilitation was achieved with dental restoration and removable partial dentures.

Adult↗
PubMed2000

The development of normal feeding and swallowing: Showa University study of the feeding function.

Since the 1980s the Department of Hygiene and Oral Health at the Showa University School of Dentistry has focused its research efforts on the development of feeding function and disorders. In addition, we have treated dysphagic children and dysphagic elderly using our feeding training program approach. The developmental course of the feeding function includes the following steps: 1) Suckle feeding and prefeeding period; 2) Acquiring the ability to swallow with lips closed; 3) Acquiring the ability to take food with lips closed; 4) Acquiring the ability to push mashed food with the tongue and anterior hard palate; 5) Acquiring the ability to perform mastication; 6) Beginning self-feeding; 7) Beginning finger feeding; 8) Beginning using table ware.

Child Development↗
PubMed1997

[Fabrication and use of two kinds of overdenture attachments].

The authors introduced the fabrication of stud attachment and bar attachment used to increase the stability and retention of overdenture. During two years' periods, the results of the clinical practice indicated: the retention of overdenture was increased and patients' masticator function was improved when attachments were used, and then the fabrications of two kinds of attachments were simple and value of attachments is cheap. The technique was popularized and used easily.

Denture Precision Attachment↗
PubMed2001

Strategies for complete denture success: beyond technical excellence.

Many patients are quite satisfied with dentures that are extremely poor, while other patients are dissatisfied with dentures that are technically excellent. Overall, some 25% of patients are likely to be dissatisfied with their artificial teeth. This article addresses the aspects of denture success not covered by technical considerations. The strategies are based on the principles of good communication and involve an understanding and respect for patients' motivations in wearing dentures. The strategies include help in the development of neuromuscular control and in training regarding mastication. Most importantly, they emphasize patient involvement in the development of the denture. Patients must be made aware of their responsibilities in achieving a satisfactory outcome in the complex patient/denture relationship.

Dentist-Patient Relations↗
PubMedDate not supplied

Oral health impact on daily performance in patients with implant-stabilized overdentures and patients with conventional complete dentures.

This cohort study (n = 83) investigated whether patients with implant-stabilized overdentures would demonstrate less impact on daily life, would have less difficulty in the mastication of different types of food, and would generally be more satisfied than patients with conventional complete dentures. The groups were comparable for gender, age of dentures, and duration of edentulism. The patients were interviewed using a questionnaire, which included the Oral Impacts on Daily Performances (OIDP) sociodental indicator. Patients with implant-stabilized overdentures were more satisfied with the comfort of their dentures, could eat a wide range of food items with less difficulty, and experienced less impact on daily life than patients with conventional complete dentures. The findings of this study support the need to consider implant-stabilized overdentures in the treatment of edentulous patients.

Activities of Daily Living↗
PubMed2001

Fibroma (myxoma) molle in a hamster (Mesocricetus auratus).

An adult female Syrian hamster (Mesocricetus auratus) presented with a large, ulcerated lesion in its right cheek pouch; this wound interfered with the animal's ability to masticate. As a result, the hamster became inappetant and lethargic and lost about 25% of its original body weight within 6 to 9 weeks of presentation. The mass was surgically excised and submitted for histopathological evaluation. Microscopically, the mass was characterized as a neoplastic process partially encapsulated with fibrous connective tissue in the submucosa. Loosely arranged bundles of spindle to stellate cells with round to oval hyperchromatic nuclei and amphophilic cytoplasm were abundant. Some cells had multiple nucleoli, and some mitotic figures were observed. Special stains were used to definitively diagnose fibroma (myxoma) molle, a rare spontaneous neoplastic lesion in the hamster.

Animals↗
PubMed2000

[Comparison of effect of the mandible setbacked by SSRO and IVRO on gnathostomatic system].

OBJECTIVE: To compare the effect of the mandible setbacked by sagittal split ramus osteotomy (SSRO) and intraoral vertical ramus osteotomy (IVRO) on gnathostomatic system. METHODS: 27 cases with mandibular prognathism were treated, 16 received SSRO and 11 IVRO. Their occlusal force and masticatory efficiency were measured preoperatively and at 3 and 6 months after operation. The condylar positions were assessed by radiography before surgery and at 6 months postoperatively. RESULTS: In three months postoperatively, the occlusal force and masticatory efficiency of IVRO group was decreased more than that of SSRO group. At six months postoperatively, the occlusal force and masticatory efficiency of SSRO group recovered quicker than IVRO group and better than that of before operation. In IVRO group, the occlusal force approached the preoperative level, the masticatory efficiency was better than preoperative value. 26/32 (81.2%) condyles were relatively retropositioned in SSRO group, 14/22 (63.6%) condyles were relatively forward positioned in IVRO group. CONCLUSIONS: The function recovery time after surgery was shorter in SSRO group. The masticator muscles were detached in varying degree and the bone segments healed slowly, the effect on gnathostomatic system was greater and recovery time after surgery was longer in the IVRO group.

Adult↗
PubMedDate not supplied

Kinesiographic investigations in children with increased nasal airways resistance.

The aim of this study is to evaluate by means of the kinesiographic test, how the muscular alteration, linked with mouth breathing, modifies mandibular dynamics. From a sample of children aged between 8-11 years, on the basis of increased nasal airways resistance measured with the forced oscillation technique, we selected a group of 14 subjects. These children underwent kinesiographic examination (K-System Biotronic) and they were compared to a control group. Certainly, the speeds reduction in the pathological group emerged as the most significant data. The mastication tracings on the frontal plane, in the group with increased nasal airways resistance, moreover appeared to be reduced in width, elongated in shape and sometimes irregularly square, compared to the bell shape typical of subjects without any dysfunctional pathologies. Considering that each subject responds in a personal manner to an increase of the nasal resistances, due to the extremely variable individual adaptability, the kinesiographic test, together with the electromyographic one, in our opinion, can assist anamnesis, clinical examination and other instrumental investigations, in the identification of those subjects in which the increase of the nasal airways resistance interferes with muscular function, laying the basis for possible modifications in the craniofacial growth.

Adaptation, Physiological↗
PubMed2001

[Evaluation of the masticatory efficiency of linear occlusal dentures].

OBJECTIVE: To study how the linear occlusal dentures perform the function with the most restricted occlusal contact areas. METHODS: A study of masticatory efficiency was made for 33 patients wearing linear occlusal dentures compared with that of 30 patients wearing anatomic occlusal dentures. RESULTS: There is no difference between the linear occlusal dentures group and the controlled group when tested by fixing mastication time, while 81.8% of the experimental group with severe RRR, and the controlled group being only 43.3%. CONCLUSION: Linear occlusal dentures work well for edentulous patients, especially for the cases with flat or depressed residual ridges.

Adult↗
PubMed2002

Temporo-mandibular joint kinetics and chewing cycles in children. A 3-year follow-up.

OBJECTIVES: To report the temporo-mandibular joint (TMJ) kinetics and masticatory function in healthy children. DESIGN: Temporo-mandibular joint palpation and electrognathographic registrations of chewing cycles were repeated for 3 years in order to evaluate changes. SETTING: Healthy children without systemic pathologies, decayed cavities and previous dental treatment. SAMPLE AND METHODS: Electrognathographic (EGN) registration of masticatory cycles and TMJ palpation were carried out on 52 patients (mean age: 5 years 8 months, range: 5 years 1 month, 6 years 8 months), by two university researchers, once a year for 3 consecutive years. TMJ palpation, differentiated TMJ synchronism (simultaneous bilateral opening movement) and TMJ asynchronism (not simultaneous bilateral opening movement), TMJ subluxation and click were observed. Electrognathographic registrations differentiated normal and abnormal jaw chewing cycles, and narrow and large cycles. RESULTS: Temporo-mandibular joint asynchronism was evident in 34 of 52 patients in the primary dentition, in 42 of 52 patients after the eruption of the first permanent molar, and in 31 of 52 patients after the eruption of the permanent incisors. TMJ subluxation increased during the full period of observation. Three temporomandibular clicks appeared after the eruption of the permanent incisors. Altered mastication was not always associated with TMJ disorders. CONCLUSIONS: In children, normal chewing cycles can coexist with occlusal discrepancies, cranio-facial growth and TMJ alterations.

Child↗
PubMed2002

Experimentally induced unilateral tooth loss: histochemical studies of the temporomandibular joint.

Occlusal abnormality may contribute to osteoarthrosis of the temporomandibular joint (TMJ). Since mechanical force may induce changes in the extracellular matrix, we tested the hypothesis that unilateral removal of teeth and the resulting unilateral mastication change the content of glycosaminoglycans (GAGs) in the TMJ condyle and disc. Lower-right-side teeth were extracted from 12 adult male rabbits, which were killed 3 or 6 weeks later. Three normal rabbits served as controls. Sections were analyzed for morphological changes and levels of sulfated GAGs in the condyle and disc. Unilateral removal of teeth led to thickening of the condylar cartilage, alterations in the morphology of chondrocyte nuclei in the condylar cartilage and disc, and increases in levels of negatively charged ions in the hypertrophic layer of condylar cartilage. Small differences were observed, after unilateral removal of teeth, between the functional and non-functional sides of the TMJ. The results suggest that in response to mechanical stress, chondrocytes alter sulfated glycosaminoglycan (GAGs) synthesis and degradation rates, resulting in an elevated level of sulfated GAGs in the condylar cartilage.

Animals↗
PubMed1975

Palatal epithelium of a monotreme and a marsupial.

The palatal epithelium of a monotreme, Tachyglossus aculeatus and a marsupial, Tarsipes spenserae were examined histologically and with the scanning electron microscope. Each animal possess keratinized palatal spines which although histologically similar, show significant differences in their external morphology. It is suggested that the spines in each case are highly differentiated filiform papillae which have developed as a compensatory mechanism of mastication, since both animals are in effect, edentulous. In the light of these findings and observations on the tongue of both animals, it is suggested that a degree of parallel evolution of the palate (as part of the masticatory apparatus) has occurred.

Animals↗
PubMed2002

Association of salivary flow rate with oral function in a sample of community-dwelling older adults in Japan.

OBJECTIVE: The purpose of this study was to determine the association of stimulated salivary flow rate with perceived salivary flow and various oral symptoms among a group of independently living elderly persons. STUDY DESIGN: The subjects were 351 persons (189 men and 162 women) with a mean age of 66.7 +/- 4.3 years. Stimulated whole saliva was collected with the mastication method. Self-assessed chewing ability and satisfaction with oral function also were evaluated. A multiple logistic regression analysis was used to determine whether an independent variable was statistically significant. RESULTS: Hyposalivation (< 0.5 mL/min) was significantly associated with gender (odds ratio, 1.67; P < .05). Hyposalivation (odds ratio, 3.40; P <.05) and low perceived salivary flow (odds ratio, 5.35; P <.05) were significantly associated with dissatisfaction with tasting. Low perceived salivary flow was also significantly associated with self-assessed chewing ability (odds ratio, 3.32; P <.01). CONCLUSION: This study suggested that hyposalivation and low perceived salivary flow were related to chewing ability and satisfaction with tasting foods.

Aged↗
PubMed2001

The role of the human lateral pterygoid muscle in the control of horizontal jaw movements.

There is a limited understanding of the normal function of the lateral pterygoid muscle (LP) and the role that this muscle plays in temporomandibular disorders. This article addresses the hypothesis that a major function of the LP is in the control of horizontal jaw movements. The range of fiber alignments suited to generating a major horizontal force vector (magnitude and direction), together with the likelihood of independent activation of subcompartments (that is, functionally heterogeneous zones) within each head, provide the possibility of a finely graded range of force vectors on the condyle to effect the fine control of horizontal jaw movements. This level of control does not appear to extend to the control of resting jaw posture, as recent single motor unit (SMU) data indicate that the LP is inactive with the jaw in the postural jaw position. Available electromyographic data demonstrate graded changes in multiunit and SMU activity with small horizontal jaw displacements at low force levels, a single preferred direction of the SMU firing rate during horizontal isometric jaw tasks, and graded changes in the SMU firing rate with horizontal force magnitude and direction. The evidence suggests that a major function of the LP is in the generation and fine control of the horizontal component of jaw movement by the graded activation of a subset of SMUs within the LP. The data also suggest that the LP is involved in the generation of horizontal force vectors, as required in parafunctional activities and heavy mastication.

Electromyography↗
PubMedDate not supplied

A survey of cusp fractures in a population of general dental practices.

PURPOSE: This study was conducted to expand the knowledge on the incidence of complete cusp fractures of posterior teeth in Dutch general practices. MATERIALS AND METHODS: During a 3-month period, data were obtained from 28 general practitioners, representing 46,394 patients. For each new case of complete cusp fracture, clinicians recorded information using a standard form with questions relating to location of the fracture, cause of fracture, and restorative status of the tooth prior to the cusp fracture. RESULTS: There were 238 cases of complete cusp fracture recorded. The results of this study indicate an incidence rate of cusp fractures of 20.5 per 1,000 person-years at risk. Molars were more frequently registered with cusp fractures than premolars (79% vs 21%). Maxillary molars presented more fractures of buccal cusps (66% vs 34%), while mandibular molars presented more fractures of lingual cusps (75% vs 25%). Almost 77% of the cases had been restored on three or more surfaces. Statistical analysis revealed a positive correlation between history of endodontic treatment and subgingival fracture location. Mastication was most frequently reported as the cause for fracture (54%), although one can argue whether the occlusal force was the cause or the immediate reason. CONCLUSION: This study revealed that complete cusp fracture is a common phenomenon in dental practice and has shown differences in cusp fracture with respect to tooth type and restorative status of the tooth. Teeth with a history of endodontic treatment are susceptible to unfavorable subgingival fracture locations.

Adult↗
PubMed2003

Discuss before fabricating: communicating the realities of partial denture therapy. Part I: patient expectations.

During planning for treatment involving cast removable partial dentures (RPDs), it is important to remember that the 2 major reasons why patients seek this treatment are to improve esthetics and to improve mastication. Treatment that is considered unsuccessful may not necessarily represent poor execution of procedures, but rather may not have fulfilled the patient's expectations with regard to these 2 goals. Searches of the Cochrane Collaboration and MEDLINE databases were conducted to identify issues pertaining to patient compliance in wearing cast RPDs. Compliance was better when the patient's chief concern was replacement of anterior teeth. The success of RPDs for replacement of teeth missing from other areas depended on the patient's perception of the value of such replacement. Maximum masticatory efficiency is equivalent for people functioning from second premolar to second premolar and those wearing partial dentures. Many clinicians believe that the prescription of partial dentures which replace teeth missing distally to the second premolars represents overtreatment.

Denture, Partial, Removable↗