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1.
J Oral Rehabil ; 27(8): 660-3, 2000 Aug.
Article in English | MEDLINE | ID: mdl-10931260

ABSTRACT

To gather knowledge related to establishing criteria for selecting soft denture liners for individual patients, the effects of certain properties of soft denture liners on stress distribution were evaluated by two-dimensional finite element analysis. A partial mandibular edentulous ridge crest was modelled. Six combinations of thickness (mucosa: 1 or 2 mm; soft denture liner: 1, 2, or 3 mm) and 18 combinations of Young's modulus (mucosa: three kinds; soft denture liner: six kinds) were analysed. The ratio of maximum to minimum stress in the mucosa (stress ratio) was calculated to estimate stress concentration. In the case of thin mucosa (1 mm thickness), the lower the Young's modulus of the soft denture liner, the lower the stress ratio. However, if the soft denture liner had a lower Young's modulus than the mucosa, stress concentrated adversely. These results suggest that the elasticity of the soft denture liner should match the elasticity of the mucosa to obtain the optimum cushioning effect.


Subject(s)
Dental Stress Analysis/methods , Denture Liners , Elasticity , Finite Element Analysis , Humans , Materials Testing , Mouth Mucosa/physiology
2.
J Prosthodont ; 8(1): 53-4, 1999 Mar.
Article in English | MEDLINE | ID: mdl-10356556

ABSTRACT

A technique for facilitating cement removal between splinted crowns is described. The technique involves tying dental floss with the large-diameter yarn portion around the embrasure of the splinted crown before cementing, and pulling it through before the cement has reached a final set. This simple, quick technique achieves removal of cement without damage to the interproximal crown surface.


Subject(s)
Crowns , Dental Debonding/methods , Cementation/methods , Denture, Partial, Temporary , Humans , Splints
3.
J Prosthet Dent ; 64(2): 153-8, 1990 Aug.
Article in English | MEDLINE | ID: mdl-2202814

ABSTRACT

An investigation was done on the effect of crown height, angle (one-half taper) and number of removals on the retention of telescope crowns. Assemblies of inner and outer crowns were constructed on master dies. Crown heights of 4 mm, 5 mm, and 6 mm were used. Cone angles of 0, 2, 4, and 6 degrees were used for each of the three heights. The inner crowns were fixed to the dies with an adhesive agent. the outer crowns were set over them and placed in a clamp. Separation forces were tested with an Instron machine (Instron Corp., Canton, Mass.). They were measured initially and after numerous 100 insertion/separation cycles up to 1000 cycles and numerous 500 insertion/separation cycles up to 10,000 cycles. The results demonstrated that the cone angle of the inner crown was more important than its height for maximum retention. Retention is rapidly lost after the cone angle exceeds 2 degrees. It was also shown that an accessory device is necessary to maintain retention capabilities after long-term use.


Subject(s)
Crowns , Denture Retention , Denture, Overlay , Analysis of Variance , Dental Stress Analysis , Denture Design , Materials Testing , Stainless Steel , Surface Properties , Time Factors
4.
Int J Oral Maxillofac Implants ; 4(3): 205-10, 1989.
Article in English | MEDLINE | ID: mdl-2639121

ABSTRACT

Differential chewing function with removable partial dentures (RPDs) and fixed prostheses supported by the single-crystal sapphire implant was evaluated in five subjects with Kennedy Class II partially edentulous mandibles by means of electromyography. Rehabilitation with the single-crystal sapphire implant resulted in regular chewing patterns with a low variation coefficient and higher activity of chewing-side masticatory muscles compared to RPD rehabilitation. This difference in chewing function between the two rehabilitation modalities could be the result of differences in stability of occlusion and neurophysiologic feedback systems.


Subject(s)
Dental Implants , Denture, Partial, Fixed , Denture, Partial, Removable , Mastication , Aluminum Oxide , Humans , Jaw, Edentulous, Partially/rehabilitation , Mandible
5.
J Oral Rehabil ; 15(4): 373-8, 1988 Jul.
Article in English | MEDLINE | ID: mdl-3049998

ABSTRACT

Mandibular movement and masticatory performance were evaluated in the edentulous patients with an experimental denture using posterior artificial teeth of different occlusal schemes in order to determine the criterion for the selection of posterior artificial teeth. Lower masticatory performance was observed with non-anatomic posterior teeth than with semi-anatomic or anatomic ones regardless of the condition of residual ridge and inclination of the horizontal condylar guidance. The value of the lateral component of the masticatory cycle was closely related to the inclination of the cusp and the value of masticatory performance. This suggested strongly that the component could be a criteria for the selection of the type of the artificial posterior teeth.


Subject(s)
Bicuspid , Denture Design , Denture, Complete , Molar , Tooth, Artificial , Aged , Aged, 80 and over , Humans , Mandible/physiology , Mastication , Middle Aged , Movement
12.
J Prosthet Dent ; 42(5): 497-501, 1979 Nov.
Article in English | MEDLINE | ID: mdl-290800

ABSTRACT

With the experimental design of this study the following conclusions were reached. 1. Biting force during maximum clenching was the greatest when the occlusal plane was made parallel to the ala-tragus line. It decreased when the occlusal plane was inclined about 5 degrees anteriorly or about 5 degrees posteriorly. 2. The efficiency of biting force exertion during maximum clenching showed the best value when the occlusal plane was made parallel to the ala-tragus line. 3. Muscle activity during clenching at various given forces was least when the occlusal plane was made parallel to the ala-tragus line. The anteroposterior inclination of the occlusal plane tends to affect the biting force, and the method with the ala-tragus line seems to be the most reasonable for occlusal plane orientation.


Subject(s)
Dental Occlusion , Dental Stress Analysis , Mastication , Masticatory Muscles/physiology , Aged , Bruxism/physiopathology , Denture, Complete , Electromyography , Female , Humans , Male , Middle Aged
13.
J Prosthet Dent ; 42(1): 12-6, 1979 Jul.
Article in English | MEDLINE | ID: mdl-156790

ABSTRACT

The results of this experiment suggest that the periodontal ligament plays a role in the efficiency of muscular activity during chewing in patients wearing overdentures. A masticatory index as an indicator of the efficiency of masticatory movement is proposed in this research.


Subject(s)
Denture, Overlay , Mastication , Periodontal Ligament/physiology , Aged , Efficiency , Electromyography , Female , Food , Humans , Male , Masticatory Muscles/physiology , Middle Aged , Muscle Spindles/physiology , Time Factors
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