Influence of mandibular free-end partial edentulism on the force exerted on maxillary anterior teeth

PurposeThe purpose of this study was to determine the influence of mandibular free-end partial edentulism and the wearing of removable partial dentures in the partially edentulous area on the force exerted on maxillary anterior teeth.MethodsA commercially available jaw model with exchangeable teeth was used. Seven experimental conditions of mandibular free-end edentulism were set up and a distal extension removable partial denture to replace missing posterior teeth was fabricated. Strain gauges were attached to the root surface of the maxillary left central incisor, canine, first premolar and first molar, and the force exerted on them was calculated based on the calibration coefficient. An occlusal load of 49 N was applied and the forces were compared with the Kruskal–Wallis test (P < 0.05).ResultsThe force exerted on the maxillary anterior teeth increased significantly as the number of remaining teeth decreased. The force exerted on the maxillary anterior teeth decreased significantly with use of a removable partial denture.ConclusionsWhen the number of remaining teeth decreases in mandibular free-end partial edentulism, the burden on the maxillary anterior teeth increases. Our findings suggest that for patients with mandibular free-end partial edentulism, wearing a removable partial denture is effective in preserving the remaining teeth by reducing excessive stress.     

Reproducibility of interocclusal recording for mandibular removable partial denture in bilateral distal extension cases

Interocclusal recording for removable partial denture in bilateral mandibular distal extension were evaluated for the differences of the interocclusal recording material utilized during different impression techniques. The purpose of this study is to develop interocclusal recording utilizing occlusion rims with high accuracy. The intraoral model with urethane rubber mucosa with 3 metallic spheres as measuring points was utilized. With the applied pressure (functional) and minimum pressure (anatomical) impression techniques, working casts were fabricated. Interocclusal recording was registered with the occlusion rim on the intraoral model unto the articulator by applying the interocclusal materials; paraffin wax (PW), ALUWAX (AW), impression paste (IP) and Exabite II (EB). Analyses were conducted with the three-dimensional analyzer and calculated for the amount of vertical and antero-posterior displacement between the intraoral model and the working cast. The results were that PW had the greatest displacement, especially with the functional impression technique, while AW had minimum displacement especially in the posterior direction. With the functional impression technique utilizing AW was revealed to minimize the amount of interocclusal displacement.     

Influence of interocclusal distance of mandibular unilateral distal extension removable partial denture on masticatory function]

The purpose of this study was to elucidate the influence on masticatory function when the mandibular unilateral distal extension removable partial denture changed the interocclusal distance. The experiments, crushability, the sense of mastication, and the masticatory strokes until swallowing, were conducted, on four subjects, using the denture with the apparatus that enabled to change the interocclusal distance. The results were as follows: The particle size distribution showed that the ratio of small particle (diameter 2.5-4.5 mm) decreased, while that of large particle (more than 5.0 mm) increased, on three of four subjects, and the value of crushability diminished. A reduction of the value of crushability when the interocclusal distance was extended more than 800 microns was found. As for the other subject, no change was recognized on the particle size distribution under experimental condition, and the value of crushability showed no significant change.     

Modified finish line in distal extension maxillary removable partial dentures

Finish line modifications provide adjustability and facilitate relining in the hamular notch as changes in tissue contour dictate. Time problems and inconvenience of dealing with a metal-acrylic resin junction, are eliminated while necessary postinsertion procedures are accomplished. In addition, the acrylic resin denture base is retained securely to the metal framework for the entire length of the external finish line.     

Esthetic removable partial denture design in replacing maxillary anterior teeth

Prosthodontic rehabilitation of missing maxillary anterior teeth requires special consideration to restore function and esthetics. This case report describes the prosthodontic management of a patient who lost three maxillary incisors due to a motor vehicle accident. A rotational path removable partial denture was constructed, for which a proximal undercut was created by means of a composite buildup to provide the retention for the prosthesis.     

Influence of loading positions of mandibular unilateral distal extension removable partial dentures on movements of abutment tooth and denture base

PURPOSE: The aim of our study was to explore the effects of different loading positions on the movements of the abutment tooth and denture base of removable partial denture with unilaterally designed framework (RPD-U). MATERIALS AND METHODS: The experiment was carried out with a simulation model of a mandible without left molars. The movements of abutment tooth and denture base of the unilateral and bilateral designs were due to 30N vertical load on 12 loading positions determined with a strain gauge circuitry. The effects of loading positions on the movements of the abutment tooth and denture base were compared between two designs. RESULTS: During the loading on buccal, lingual positions, and the most disto-central position the movements of the abutment tooth and denture base of the unilateral design were significantly greater than those of the bilateral design (P < 0.01). During the loading on the three mesio-central positions the movements of the abutment tooth and denture base were equal between designs, and were significantly lower than during the loading on the other positions (P < 0.01). CONCLUSION: Ending the denture teeth at the mesial cusp of second molar and positioning the occlusal contacts over the ridge crest adequately stabilize the abutment tooth and denture base of RPD-U.     

Esthetics in the edentulous: clinical steps for recovering of maxillary anterior teeth harmony

Smile designing for edentulous patients has not been much investigated; the selection of artificial teeth is a task that follows multiple consequential steps such as choosing their form, size, material, color and disposition. Even if smile designing is thought to involve some artistic abilities, specific techniques or suggestions have been proposed in the literature to perform each step of the selection of artificial teeth, keeping in mind the importance of consultation and understanding of the patient preferences. This article will focus on the recovering of maxillary anterior teeth harmony in an edentulous patient; a clinical case report will show the rationale process of anterior teeth selection, supported by scientific guidelines found in the literature.     

无牙颌单侧上颌骨缺损种植修复设计的三维光弹应力分析

目的：探讨采用双侧种植体植入修复无牙颌单侧上颌骨缺损的可行性,并优化其设计。方法：采用三维光弹应力分析法对应用种植杆卡式附着体赝复体的上颌骨缺损患者载荷下的支持组织进行应力观察和分析。结果：双侧种植修复设计的支持组织和种植体的应力分布明显优于单侧种植修复设计。结论：无牙颌单侧上颌骨缺损的修复应采用双侧种植长桥架设计。     

Influence of length of food platform on masticatory performance in patients missing unilateral mandibular molars with distal extension removable partial dentures

Reduction of the size of food platform of a distal extension removable partial denture has been recommended to decrease functional load on the abutment teeth and residual ridges. The purpose of this study was to investigate the influence of shortening food platform on masticatory performance. Eight subjects unilaterally missing mandibular molars participated in the study. A unilateral design was used for the denture framework. The length of the food platform was changed as follows. Initially, (A) was adjusted so that the distal end of the platform was in accordance with the distal end of maxillary second molar. Next, the platform was shortened successively to 15 mm (B) and 10 mm (C). Subjects were asked to masticate 2-colored wax cubes to evaluate masticatory performance. Mixing Ability Index was calculated from the color mixture and the form of masticated cubes. Repeated measures one-way ANOVA indicated significant difference of Mixing Ability Index among platforms (P < 0.0001). The Dunnett's test indicated no significant difference between A (1.27 +/- 0.29) and B (1.36 +/- 0.29), and a significant difference between A and C (0.89 +/- 0.30), (P < 0.001). Masticatory performance decreased significantly when the length of food platform was shortened to 10 mm.     

Determination of approximate size of maxillary anterior denture teeth when mandibular anterior teeth are present. Part III: Relationship of maxillary to mandibular central incisor widths

The average width of a natural maxillary central incisor is 8.92 mm. This value is determined from the results of three studies of natural dentitions. The average width of a mandibular central incisor is 5.5 mm. The average ratio produced by dividing the average maxillary central incisor width by the average mandibular incisor width is 1.62. The factor of 1.5 times the width of a mandibular central incisor produces a maxillary central incisor width that is too narrow. The width of a mandibular central incisor plus half the width of the mandibular lateral incisor also produces a maxillary central incisor width that is too narrow. There may be a tendency to undersize the maxillary prosthetic dentition. The ratio of 1.62 can be used to select the appropriate width for a missing maxillary central incisor when given the width of the mandibular central incisor. This ratio of 1.62 is also valuable to verify the dimension of a selected artificial maxillary central incisor when the patient complains that the tooth is too large. If substitutions or adjustments are made in the mold, the desired canine-to-canine measurement produced by the ratio range of 1.3 to 1.38 reported in Parts I and II of this study should be maintained.     

The bilateral distal extension removable partial denture: mechanical problems and solutions

Tbe bilateral distal extension removable partial denture has inherent problems of retention and stability, affecting not only the integrity of denture bearing tissues and associated structures, but also patient acceptance and compliance. This paper examines factors that contribute to and exacerbate the functional movement of free-end saddle prostheses, discusses techniques used to overcome these problems and lists alternative strategies for the management of the Kennedy class I patient.     

Class III bilateral posterior crossbite with three horizontally impacted maxillary anterior teeth

What's in a pretty face? In our world, unfortunately, too much. As orthodontists our goal should be to provide our patients with a stable, functional occlusion. Consider, however, the importance of changing our patients' future by significantly improving their facial esthetics. The combination of a very narrow maxillary arch, three absent upper left incisors, and a protrusive lower jaw provide a platform for dramatic improvement in our patients' facial esthetics.