• Journal of Dental Rehabilitation and Applied Science
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• v.27 no.4
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• pp.437-447
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• 2011

In patients who used removable partial dentures for a long period of time, gradual alveolar bone resorption occurs in edentulous area. However, in residual teeth area, alveolar bone is maintained sound. This causes an imbalance in intermaxillary distance between a maxillae and a mandible which is intensified due to expansion in vertical and horizontal bone amount difference between the two area as time passes. As the result, this shows a substantial difference in vertical position according to the period of teeth loss even after residual teeth loss. As in this situation, a patient with bilaterally and anterio-posteriorly different intermaxillary distance, various prosthodontic problems can be caused in fixed implant prosthodontics and implant overdenture. This study shows a case in which implant-supported removable partial denture was fabricated considering residual alveolar bone height after teeth loss in a patient who had been using a distal extension removable partial denture for a long period of time. In anterior area with short intermaxillary distance, fixed prosthodontics were fabricated with implant placement and in posterior area with long intermaxillary distance, a removable partial denture was fabricated. Finally, a small number of implants were placed without additional surgery and economical and comfortable treatment results were shown.

• Journal of Technologic Dentistry
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• v.28 no.2
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• pp.331-346
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• 2006

Free-end partial dentures, which are supported by teeth surrounded by dental root membranes and elastic mucous membrane tissues, may cause stress to the abutment teeth due to external force imposed on the denture base, increase the mobility of the abutment teeth, and bring about a change in the periodontal tissue. General retainers used in partial dentures are categorized into clasp, attachment, and Konus crown. Stress imposed on the abutment teeth and mobility of the denture base have relations with the lifetime of a crown and abutment teeth, and have direct relations with the chewing ability. Thus, a need arises to make a comparative analysis of stress of the three direct retainers on the abutment teeth and interpret the mobility of the denture base. This study designed three kinds of removable partial dentures (one kind of attachment partial denture, one kind of Konus crown partial denture, and one kind of clasp partial denture), and fabricated Dentiforms of bilateral partial dentures (Kennedy Class I) with lower left 1st premolar and lower right 1st and 2nd premolars being as the abutment teeth. A strain gauge was installed in the mesial and distal surface of the lowerr left 1st premolar (No. 34) of the fabricated dentiform and in the lower part of the denture base, and installed were a clasp partial denture, an attachment partial denture, and a Konus crown partial denture. Then, the vertical static load of 5kgf and 7.5kgf at the occlusion surface of the lower left No. 6 molar was generated for a total of 20 frequencies of load each using a push-full gauge, and thus a change in the output of the strain gauge was measured. With the respective application of Konus crown, attachment and RPI clasp in the free-end partial denture, surveyed was the distribution of stress imposed on the abutment teeth and the denture base according to the location of occlusion force load so as to come up with the following results. 1. Konus crown and attachment partial dentures generated much stress, and more stress on the abutment teeth than RPI clasp dentures did. Attachment dentures tended to further intensify stress on the abutment teeth than Konus crown dentures did. 2. Attachment dentures and Konus dentures imposed less stress on the denture base than RPI clasp dentures did. There was no stress difference between Attachment and Konus crown dentures. 3. Dentures that were designed with the application of retainers using sturdy linkage methods tended to be less mobile.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.6
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• pp.753-759
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• 2007

Statement of problem. In distal extension removable partial denture, the preservation of health of abutment teeth is very important, but abutment teeth are subjected to unfavorable stress under unilateral loading specially. Purpose. The purpose of this study was to investigate the biomechanical effects of mandibular removable partial dentures with various prosthetic designs under unilateral loading, using strain gauge analysis. Material and methods. Artificial teeth of both canines were anchored bilaterally in a mandibular edentulous model made of resin. Bilateral distal extension removable partial dentures with splinted and unsplinted abutments were fabricated. Group 1: Clasp-retained mandibular removable partial denture with unsplinted abutments Group 2: Clasp-retained mandibular removable partial denture with splinted abutments by 6-unit bridge. Group 3: Bar-retained mandibular removable partial denture Strain gauges were bonded on the labial plate of the mandibular resin model, approximately 2 mm dose to the abutments. Two unilateral vertical experimental loadings (30N and 100N) were applied subsequently via miniature load cell that were placed at mandibular left first molar region. Strain measurements were performed and simultaneously monitored from a computer connected to data acquisition system. For within-group evaluations, t-test was used to compare the strain values and for between-group comparisons, a one-way analysis of variance (ANOVA) was used and Tukey test was used as post hoc comparisons. Results. The strain values of group 1 and 2 were tensile under loadings. In contrast, strain values of group 3 were compressive in nature. Strain values increased as the applied load in increased from 30N to 100N (p<.05) except for right side in group 1. Under 30N loading, in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 100N loading in left side, group 1 showed higher strain values than groups 2 and 3 in absolute quantity (p<.05). And group 2 showed higher strain values than group 1 (p<.05). In right side, group 1 and 2 showed higher strain values than group 3 in absolute quantity (p<.05). Under 30N loading, group 2 and 3 showed higher strain values in right side than in left side. Under 100N loading, right side strain values were higher than left side ones for all groups. Conclusion. Splinting of two isolated abutments by bridge reduced the peri-abutment strain in comparison with unsplinted abutments under unilateral loading. Bar-retained removable partial denture showed the lowest strain of three groups, and compressive nature.

• Journal of Technologic Dentistry
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• v.8 no.1
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• pp.85-90
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• 1986

The effect of splinting on aqbutment tooth distal movement was performed in vitro study. An acrylic resin mandibular model with missing 2nd premolars, molars and a removable partial denture framework were constructed. The roots of the canines, 1st premolars and edentulous ridges were coated with silicone rubber. A modified Ney Surveyor was used for vertical load appkication, and abutment tooth distal movement were measured with a dial gauge with four conditions of splinting methods were tested by applying unilateral vertical loadings. The results are follows; 1. The magnitude of abutment tooth distal movement on the non-load side was less 40$\sim$69% than that occurred on the load side. 2. On the load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(30%), non-load side double abutment(10%), double abutments of both sides(40%) was compared with single abutments of both sides. 3. On the non-load side, reducing effect of splinting on abutment tooth movement in the condition of load side double abutment(5%), non-load side double abutment(22%), double abutments of both sides(59%) was compared with single abutments of both sides. 4. The magnitude of abutment tooth distal movement in the condition of double abutments of both sides was less 40$\sim$59% than that in the condition of single abutments of both sides.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.154-166
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• 2004

Statement of problem: In distal extension removable partial denture, the preservation of health of abutment teeth are very important, but they are always subjected to unfavorable stress. Purpose: The purpose of this study was performed to investigate the effects of abutment splinting and design of direct retainer on the stress distribution of abutments in unilateral distal extension removable partial dentures. Material and method: Abutments were splinted by different method. In group 1, autment teeth were not splinted, in group 2, canine and 1st premolar were splinted, and in group 3, canine, 1st and 2nd premolars were all splinted. Three different types of direct retainer such as Akers clasp, RPI clasp, and wrought wire clasp were designed. Strain was measured with Switch & Balance Unit(SB-10, Measurement Group Instruments Division, Raleigh USA) and Strain Indicator(P-3500, Measurement Group Instruments Division, Raleigh, USA) 15kg of vertical and oblique loads was applied at central fossa of missing 2nd molar area. Results : The strain on lingual side of 2nd premolar was the greatest, and abutment splinting induced decrease of strain on buccolingual side of 2nd premolar. The strain of loaded area was decreased by abutment splinting and there was no statistical difference of strain between Group2 and Group 3, and strain on 2nd premolar in wrought wire clasp was the least. Conclusion: Within the limitations of this study, splinting of two distal abutment teeth is enough for stress distribution widely, and wrought wire clasp was more benefitable than others.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.58-65
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• 2015

For the rehabilitation of fully edentulous patients, implant-supported removable partial dentures can be considered as one of the treatment options with complete dentures or implant-supported overdentures. If removable partial dentures are used in combination with a small number of implants placed in strategically important positions, it can offer additional stability, retention and support through implants and reduce a burden of surgical procedures compared with fixed implant-supported prostheses with extensive implant placement. Moreover, the economical benefit can be expected as well. The purpose of this case report is to present a treatment in which an implant-supported removable partial denture was fabricated considering residual alveolar bone status and demands after teeth loss in a patient who had been using a distal extension removable partial denture for a long period of time. In anterior area, fixed prostheses were fabricated with implant placement and in posterior area, short implants provide only support for the removable partial denture. In addition, denture base and clasp were made of thermoplastic acrylic resin. Finally, functionally and aesthetically satisfying treatment results can be achieved.

• Journal of Korean Dental Science
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• v.10 no.2
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• pp.87-95
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• 2017

This case study was to report the possible increase in the denture retention and psychological relief using the implant-supported fixed prostheses in a completely edentulous patient. The implants were placed in the anterior portion of the mandible in a patient who had completely edentulous state following the extraction of residual abutment teeth, and consequently a distal extension removable partial denture was fabricated. The patient's adaptation and satisfaction to the new prosthesis was monitored and confirmed in terms of masticatory function and esthetics, by restoring the oral condition similar to initial status before the residual teeth extraction. After 6 months, radiographic examination confirmed that both the abutment teeth and the implants were stable and well maintained. Considering the relatively short clinical follow-up period, however, continuous long-term monitoring was required.

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.17-40
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• 1987

The purpose of this study was to clarify the effect of clasp design on abutment tooth adjacent to a distal extension base under the influence by the location of functional loading. The RPI clasp, the Akers clasp and the combination clasp were selected for evaluation. Tests were performed at 10Kg, 20Kg, 30Kg loads on the buccal, central, lingual, mesial and distal positions of loading platform of each mandibular distal extension partial denture. The laser reflexion method was used for three dimensional measurement of abutment movement, which is possible to measure precisely without contact. The movement in the mesiodistal(X), buccolingual(Y), and occlusoapical(Z) directions and the rotational movement(R) were measured, and in addition, the total movement (SV) as expressed by the three dimensional summation vector independent of direction was calculated. The data were analyzed using Student t-test, p<.05. The following results were obtained from this study; 1. Clasp design did not generally affect the direction of abutment tooth movement except the movement in an undesirable occlusal direction in case of the Akers clasp and the combination clasp. 2. The greater the load on the prosthesis, the greater was the abutment tooth movement, and the direction of abutment tooth movement was affected by positional loading. 3. Each prosthesis was dislodged from the test base under the small amount of load in the distal load position, and the buccal loading showed the greatest abutment tooth movement under the maximum load. 4. RPI clasp was evaluated as the most favorable design.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.338-344
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• 2016

Implant supported removable partial denture (ISRPD) using the implants enables favorable rehabilitation by complementing biomechanical limitations of the conventional removable partial denture (RPD). However, continuous recall check is necessary for evaluation of the mechanical and biological complications to ensure good long-term prognosis of ISRPD. This clinical report describes the complication and management in patient of Kennedy class I edentulism with ISRPD using healing abutment. The wear and fracture of healing abutment occurred at 36 months after delivery. So, healing abutment was replaced by connecting $Locator^{(R)}$ abutment for altering into the implant retained partial overdenture.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.1
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• pp.43-61
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• 1990

The laser reflexion method is a new technique which permits precise contactless measurement and observation of tooth mobility as well as tooth movement. The purposes of this study were to clarify the reliability of the laser reflexion method in clinical application and to measure the abutment tooth movement according to clasp design. This study was designed to determine 1) How much a bending movement of the impression plate stand affects the position of the reflexion pattern and how precise the patient bites into plate 2) Which clasp design causes greater movement of the abutment tooth. Under medium and maximum bite forces, tests were performed on central loading position which was 13mm distal to terminal abutment tooth of distal extension removable partial denture. The movement in the mesiodistal and buccolingual directions was measured. The Duncan's New Multiple-Range test was used to compare the means for the four castings under each direction-load combination; and the paired sample t-test was for medium and maximum bite forces. From this experiment, the following results were obtained. 1. The Roach clasp, the combination clasp, the RPI clasp, and the Akers clasp did not significantly differ in their effects on buccolingual movement of the abutment tooth. 2. The direction of abutment tooth movement was not significantly altered by clasp design and all abutment tooth movements were oriented distobuccally. 3. Under medium bite force, the Akers clasp caused greater distal movement of the abutment tooth than did the combination clasp and the RPI clasp. Under maximum bite force, the Akers clasp caused greater distal movement of the abutment tooth than did the RPI clasp. 4. The testing apparatus and procedures used in this study(laser reflexion method) proved to be reliable in clinical application.