• The Journal of Korean Academy of Prosthodontics
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• v.57 no.4
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• pp.495-505
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• 2019

This study reported the treatment of a patient with excessive worn dentition and limited maxillo-mandibular space for restoration, utilizing the computer-aided design and computer-aided manufacturing (CAD/CAM) technology. After the thorough examination of the patient's occlusal vertical dimension (OVD), full mouth rehabilitation was planned with increase of the OVD. The patient was satisfied with the provisional restorations establishing the increased OVD. The horizontal and vertical data of the patient's jaw relation that the provisional restorations contained were transferred to the definitive metal ceramic fixed prostheses by double scanning and three-dimensional printing. After the fixed restorations were cemented to the abutments, electronic surveying and three-dimensional printing were used to fabricate metal frameworks for the patient's removable partial dentures. The mandibular definitive removable prostheses were delivered to the patient's mouth and the full mouth rehabilitation procedures were completed. The digital technologies used for this case produced fixed and removable restorations satisfactory in masticatory, phonetic and aesthetic functions to both the patient and the dental clinician.

• The Journal of Advanced Prosthodontics
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• v.7 no.2
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• pp.178-182
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• 2015

Ehlers-Danlos syndrome is an autosomal dominant hereditary disorder of connective tissue, while familial gigantiform cementoma is a condition that usually manifests as multiple radiopaque cementum-like masses throughout the jaws. This case report discusses the oral management and prosthetic rehabilitation of two patients presenting familial gigantiform cementoma with Ehlers-Danlos Syndrome.

• The Journal of Korean Academy of Prosthodontics
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• v.53 no.1
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• pp.74-80
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• 2015

When oral cancer is occured, one may experience problems such as lip defect, necrosis of periodontal tissue and cervical caries caused by radiotherapy. According to ADI (Association of dental implantology), recent radiotherapy on jaw bone could be a relative contraindication of implant treatment. Due to this controversy, in most cases, treatment is done with removable dentures rather than implants. Especially, lip defect caused by an oral cancer operation have a serious repercussion on the retention of the denture. In this case report, patient with upper lip cancer had undergone resection primarily and secondary radiotherapy was done periodically. As a result, upper teeth of patient were extracted gradually and lower teeth showed very poor periodontal status. Therefore, Polident$^{(R)}$ denture adhesive cream (GlaxoSmithKline, London, England) was applied on maxillary complete denture to overcome reduced retention due to the lip defect and double crown RPD with friction pin was applied on the mandible successfully for two years.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.1
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• pp.31-39
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• 2018

The collapse of the posterior occlusion destroys the normal occlusal plane and causes excessive wear reducing the vertical dimension. Reduced vertical dimension of occlusion causes not only aesthetic and functional problems but also overloading on the temporomandibular joints and abnormalities of muscle nerve system. In order to improve the collapsed occlusal relationship, it is necessary to consider the change of the vertical dimension. It is necessary to make a precise diagnosis and analysis before the treatment and to evaluate the adaption of patient to the new vertical dimension of occlusion. A patient with excessive overbite often has occlusal problems of tooth wear and tooth eruption. Considering these considerations, overall prosthodontic restoration is required to solve the problem. A patient of 68 year old man in this case who suffered major tooth wear and maxillary posterior teeth loss was treated with elevation of vertical dimension of occlusion by maxillary removable dental prosthesis and mandibular fixed prosthesis.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.249-267
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• 1994

The purpose of this study was to compare the fatigue, physical properties, flexibility and surface roughness of titanium used in removable partial dentures with those of a type IV and alloy and a cobalt- chromium alloy. Fatigue testing subjected the test specimen to rapid cycling at a given stress until failure occurred by using a small-sized, electrodynamic type bending fatigue testing machine. The S-N curves for the framework materials were generated. For tensile testing, a tensile bar as described in the ADA Specification No.14 was subjected to tensile loading until failure occurred. Load-displacement curves were generated for 18 gauge round specimen and tapered half round specimen. Then the flexibilities were calculated. The surface roughnesses were compared by analyzer. Through analyses of the data, the following conclusions were obtained. 1. The fatigue property of titanium was higher than that of a type IV gold alloy$(p\leq0.05)$, but there was no significant difference between titanium and a cobalt-chromium alloy $(p\geq0.05)$. 2. The yield strength, the ultimate tensile strength and Victors hardness of titanium were higher than those of a type IV gold alloy but lower than those of a coalt-chromium alloy$(p\leq0.05)$. 3. The percentage of elongation and reduction of area of titanium were the highest $(p\leq0.05)$. 4. The surface roughness of titanium was the greatest$(p\leq0.05)$. 5. The flexibility of titanium was lower than that of a type IV gold alloy but higher than that of a cobalt-chromium alloy$(p\leq0.05)$.

• 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.

• The Journal of Advanced Prosthodontics
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• v.13 no.5
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• pp.304-315
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• 2021

PURPOSE. Esthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue. MATERIALS AND METHODS. PEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05). RESULTS. The retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively). CONCLUSION. Thermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.206-214
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• 2009

Statement of problem: There are common clinical cases in which the mandibular first and second molars are missing unilaterally. Purpose: This study was designed to compare and evaluate the magnitude and distribution of stress produced by four kinds of mandibular unilateral free-end removable partial dentures that could be applied clinically in Kennedy class II cases. Material and methods: Four unilateral free-end removable partial dentures using clasp, Konus crown, resilient attachment, and flexible resin were fabricated on the photoelastic models of the Kennedy class II cases. The vertical load of 6㎏ was applied on the central fossa of the first molar of every removable partial denture in the stress freezing furnace and the photoelastic models were frozen according to the stress freezing cycle. After these models were sliced mesio-distally to a thickness of 6mm, the photoelastic isochromatic white and black lines of the sliced specimens were examined with the transparent photoelastic experiment device and photographs were taken with a digital camera. The fringe order numbers at eight measuring points in the photograph were measured with the naked eye. Results: The maximum fringe order number of each sliced specimen and the fringe order number at the residual ridge just below the loading point were in the decreasing order of the unilateral removable partial dentures using flexible resin followed by clasp, resilient attachment, and Konus crown. The fringe order number at the root apex of the second premolar was in the decreasing order of the unilateral removable partial dentures using clasp followed by flexible resin, Konus crown, and resilient attachment. Conclusion: The removable partial denture using Konus crown showed the most equalized stress distribution to the supporting alveolar bone of abutment teeth and residual ridge under the vertical loads. The removable partial denture using flexible resin can be applied to the case that has a better state of residual ridge than abutment teeth.

• The Journal of Korean Academy of Prosthodontics
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• v.57 no.1
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• pp.18-23
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• 2019

Patients with cleft lip and palate have several problems such as oro-nasal communication, dental cross-bite caused by the insufficient growth of maxilla, poor pronunciation and esthetic problem. Removable denture with maxillary double crown near cleft palate and with clasp in the posterior teeth was used to solve the problems of the patient with cleft lip and plate. Double crowns make up for the insufficient mucosal support caused by the mucosa and alveolar bone loss in cleft lip and palate. Double crowns also allow easy repair of denture in case of abutment teeth extraction. In this case, 55-year-old female patient had bilateral cleft lip and palate and few remaining teeth on anterior maxilla. Prosthetic treatment was done for patient with bilateral cleft lip and palate to close oro-nasal communication using maxillary double crown and clasp retained removable denture. As a result, oro-nasal communication was effectively closed and the cross-bite was easily corrected by double crown and clasp retained denture. In addition, pronunciation and appearance were also improved.

• The Journal of Korean Academy of Prosthodontics
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• v.62 no.3
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• pp.215-223
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• 2024

The patient in this case presented with a desire to have new dentures due to discomfort with existing ones. At the initial visit, all of teeth were missing except for the mandibular left second molar. As the patient was 65 years old, treatment with dentures and implant-supported prostheses was possible under the national health insurance system, and the patient opted for the mandibular denture using implant. Temporary prostheses were initially provided for patient adaptation, and following successful adaptation period, the treatment progressed. A maxillary complete denture and a mandibular implant-supported denture using two implants in the canines were fabricated. The mandibular denture is a Kennedy Class II removable partial denture which consists of a six-unit porcelain fused to metal fixed dental prostheses supported by the implant in the canines on both sides and left second molar serving as the abutments. Despite severe bone resorption and insufficient abutment teeth, the patient expressed satisfaction with the treatment results. In cases with economic and anatomical constraints affecting the feasibility of complete denture, implant-supported overdenture, and implant-supported fixed dental prostheses, an implant-assisted removable partial denture using implant surveyed crowns proves to be a viable and effective alternative treatment option. Nevertheless, the current dearth of scientifically rigorous studies underscores the necessity for meticulous regular check-up and occlusal assessment.