• 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.33 no.2
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• pp.358-394
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• 1995

The author studied the actual conditions on the production of dental prosthesis made in laboratories, and also studied interrelationships between dentists and laboratory technicians in both personal and technical aspects. Two hundred-eighty four technicians, work in dental laboratories presently, were surveyed via mail and direct contact during the period from June 1 to June 30 and August 27 to August 28 in 1994 respectively. The obtained results were as follows : 1. Among the respondents, 90.5% we re working in commercial dental laboratories and their laboratories were mainly located in the Seoul area(40.9%, P<0.05). The numbers of employees in these laboratories were less than 10 persons(70.0%, P<0.01), and 75.9% of these laboratories have been in operation less than 15 years. 2. Most laboratory procedures were accomplished according to established disciplines. However, procedures such as die trimming in fixed restorations and the qualifications of the people designing removable partial dentures were not. Other problem areas were boxing of the working cast, the person determining the posterior palatal seal area, selection and arrangement of artificial teeth, occlusion rim correction and laboratory remounting of the processed denture in complete denture restorations. 3. Only half of the requesting dentists could send work authorizations to the laboratories with their work and even so, its contents were quite lacking. Consequently, there must be some standards in writing work authorization. 4. Technicians most desired clean and accurate impressions in fixed and removable dentures, and enough tooth reduction in porcelain fused to metal restorations. 5. For the establishment of better relationships between dentist and dental technician, the respondents desired the establishment of equal footing first(33.5%), and frequent conversations and muture understanding second(25.9%).

• The Journal of Advanced Prosthodontics
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• v.8 no.2
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• pp.116-124
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• 2016

PURPOSE. The aim of the present study was to evaluate, by means of strain gauge analysis, the effect of different implant angulations on strains around two implants retaining mandibular overdenture with Locator attachments. MATERIALS AND METHODS. Four duplicate mandibular acrylic models were constructed. Two implants were inserted in the canine regions using the following degrees of distal inclinations: group I (control); $0^{\circ}$, group II; $10^{\circ}$, group III; $20^{\circ}$, and group IV; $30^{\circ}$. Locator pink attachments were used to connect the overdenture to the implants and Locator red (designed for severely angled implants) was used for group IV (group $IV_{red}$). For each group, two linear strain gauges were attached at the mesial and distal surfaces of the acrylic resin around each implant. Peri-implant strain was measured on loading and non-loading sides during bilateral and unilateral loading. RESULTS. For all groups, the mesial surfaces of the implants at loading and non-loading sides experienced compressive (negative) strains, while the distal implant surfaces showed tensile (positive) strains. Group IV showed the highest strain, followed by group III, group II. Both group I and group $IV_{red}$ showed the lowest strain. The strain gauges at the mesial surface of the loading side recorded the highest strain, and the distal surface at non-loading side showed the lowest strain. Unilateral loading recorded significantly higher strain than bilateral loading. CONCLUSION. Peri-implant strains around two implants used to retain mandibular overdentures with Locator attachments increase as distal implant inclination increases, except when red nylon inserts were used.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.198-204
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• 2017

Maxillofacial defect comes from congenital defect, trauma and surgical resection. Patients with intraoral defect are commonly related to maxillary defect and they need prosthetic rehabilitation. Functional reconstruction of partially edentulous mandible has many limitations. However, if both condyles are intact, maxillofacial prosthesis using partial denture give competent results. In this case, a patient of 58 year-old male has a defect on palate and left mandibular posterior teeth from gunshot. The maxillary defect of this patient is Class IV according to Aramany classification and the mandibular one is Type V according to Cantor and Curtis classification. For retention of the obturator, remaining teeth are fully utilized and artificial teeth are arranged harmoniously to provide stable occlusion. Mandibular RPD covered limited range of deformed soft tissue derived from mandibular resection surgery. With these treatments, the patient in this case showed improvements in mastication, swallowing and speech.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.259-268
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• 2007

purpose: This study was to evaluate the shear bond strength of Lithium Disilicate Glass-Ceramic by removable method of temporary cement on the abutment tooth. Material and Method: Sixty molar teeth of human with the occlusal surface up were mounted in acrylic resin blocks. The 45 specimens were prepared to exposure dentin by diamond bur and the eugenol-containing temporary cement($Cavitec^{TM}$ ($KERR^{(R)}$, U.S.A)was applied to the dentin surfaces. After initial removal of the cement with a dental explorer, the specimens were divided into 4 groups of 15 specimens each. The dentin surfaces of the specimens were treated by rotary instrument with as follow pastes: $Zircate^{(R)}$ prophy paste(Dentsply, U.S.A), Radent Prophy Paste(Pascal company,inc. U.S.A), and Dental pumice(Wip mix corporation,U.S.A). An adhesive resin luting agent(Variolink $II^{(R)}$, Ivoclar Vivadent, Leichtenstein) including Monobond-S and $Excite^{(R)}$ was applied to all specimens. The ceramic specimens were made with an A1 ingot of IPS Empress $II^{(R)}$ (Ivoclar Vivadent, Leichtenstein). After the specimens were stored in distilled water for 48hr, the shear bond strength(MPa) was measured by a Universal testing machine(Zwick 145641, Zwick, Germany) at a 1mm/min cross-head speed. The data were statistically analyzed by one-way ANOVA and Duncan's multiple range test. Results: In all group, there were no significant differences in comparison with the control group(p>0.05). The pattern of most failure showed the mixed type of cohesive and adhesive failure. Conclusion: Resin bond strength of IPS Empress $II^{(R)}$ was not affected by removal method of the temporary cement.

• The Journal of Advanced Prosthodontics
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• v.12 no.6
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• pp.338-343
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• 2020

PURPOSE. The present study aimed to investigate the relationships between the crown form of the upper central incisor and their labial inclination, overbite, and overjet. MATERIALS AND METHODS. Maxillary and mandibular casts of 169 healthy dentitions were subjected to 3D dental scanning, and analyzed using CAD software. The crown forms were divided into tapered, square, and ovoid based on the mesiodistal dimensions at 20% of the crown height to that at 40%. The degree of labial inclination of the upper central incisor was defined as the angle between the occlusal plane and the line connecting the incisal edge and tooth cervix. The incisal edges of the right upper and lower central incisor that in contact with lines parallel to the occlusal plane were used to determine the overbite and overjet. One-way ANOVA was performed to compare the labial inclination, overbite, and overjet among the crown forms. RESULTS. The crown forms were classified into three types; crown forms with a 20%/40% dimension ratio of 1.00±0.01 were defined as square, >1.01 as tapered, and <0.99 as ovoid. The labial inclination degree was the greatest in tapered and the least in square. Both overbite and overjet in tapered and ovoid were higher than those in square. CONCLUSION. Upper central incisor crown forms were related to their labial inclination, overbite, and overjet. It was suggested that the labial inclination, overbite, and overjet should be taken into consideration for the prosthetic treatment or restoring the front teeth crowns.

• The Journal of Advanced Prosthodontics
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• v.13 no.1
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• pp.55-64
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• 2021

PURPOSE. To investigate the biomechanical effect of marginal bone resorption (MBR) on the mandibular mini implant (MI)-retained overdenture (MI-OD) on the edentulous model. MATERIALS AND METHODS. The experimental mandibular edentulous model was modified from a commercial model with 2 mm thick artificial soft tissue under denture base. Two MIs (Φ2.6 mm × 10 mm) were bilaterally placed between the lateral incisor and the canine area and attached with magnetic attachments. Three groups were set up as follows: 1) alveolar bone around the MI without MBR (normal group), 2) with MBR to 1/2 the length of the implant (resorption group), and 3) complete denture (CD) without MI (CD group). Strain around the MI, pressure near the first molar area, and displacement of denture were simultaneously measured, loading up to 50 N under bilateral/unilateral loading. Statistical analysis was performed using independent-samples t test and one-way ANOVA (α=.05). RESULTS. The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure in CD was higher than in MI-ODs (P<.05), while there was no statistical difference between the normal and resorption group (P>.05). Similarly, the CD demonstrated a greater displacement of the denture base than did the MI-ODs during bilateral and unilateral loadings (P<.05). CONCLUSION. The strain around the MI with MBR was approximately 1.5 times higher than that without MBR. The pressure on posterior alveolar ridge and denture displacement of MI-ODs significantly decreased compared to CDs, even when MBR occurs. Bilateral balanced occlusion was recommended for MI-ODs, especially when MBR occurred.

• Journal of Dental Rehabilitation and Applied Science
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• v.30 no.1
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• pp.45-52
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• 2014

Diagnosis and treatment planning is initial step to fabricate removable partial denture, and one of most important factor influencing the prognosis. Partial edentulous patients have various condition of remaining teeth and oral mucosa. Therefore, for the proper diagnosis and treatment planning for each patient, getting many informations from patients during initial examination and fabricating accurate diagnostic cast are required. Especially, because the use of various diagnostic tools and surveying of diagnostic cast will be a guide for the abutment teeth selection, oral preparation and design of partial denture, dentist should understand and be able to apply this procedure during diagnosis.

• Journal of Dental Rehabilitation and Applied Science
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• v.29 no.4
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• pp.384-390
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• 2013

Postinsertion problems tend to be minimized when a sequential insertion procedure is followed. However, problems may occur as the result of one or any combination of comfort, function, esthetics, and phonetic difficulties. Following the insertion of a partial denture, an appointment for review in approximately 7 days should be made for the patient. At the review visit, the patient should be questioned concerning any problems that have been experienced when wearing the denture. A thorough examination should then be carried out of the oral tissues and the denture, in the course of which signs of tissue damage may be observed. A diagnosis is then made of the cause of all the problems revealed in the history and examination procedures. Appropriate treatment should then be applied to resolve these problems.

• The Journal of Korean Academy of Prosthodontics
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• v.56 no.2
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• pp.95-104
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• 2018

Purpose: The purpose of this study is to analyze the factors affecting the longevity of failed prosthesis and the success rate of the prosthesis based on the data evaluated with the newly developed Korean Academy of Prosthodontics (KAP) criteria. Materials and methods: Evaluation was performed in the restored prosthesis for patients who visited the prosthodontics department of the 13 dental university hospitals and general hospitals. The status of the prosthesis was classified into four categories: Good, Fair, Bad, Worst. The success was recorded if only the category was classified in 'good'. The mean duration of failed prostheses and the success rate through Kaplan-Meier method were analyzed. Results: A total of 1,804 cases of prosthesis were evaluated: 810 cases of fixed dental prostheses (FDP), 519 cases of Removable Dental Prostheses (RDP), and 475 cases of implant prosthesis. The mean duration of failed FDP was $11.41{\pm}0.30years$ and the median was 10 years. The mean duration of failed RDP was $8.18{\pm}0.29years$ and the median was 7 years. The mean duration of failed implant prosthesis was $7.99{\pm}0.30years$ and the median was 7 years. The factors related to the failure were as follows: number of units, abutments, abutments treated with root canal, and plaque index in FDPs; treated and opposing dentition in RDPs; the number of implants, duration of use, and plaque index in implant prostheses. Conclusion: The average duration of failed prosthesis was 11.41 years for FDPs, 8.18 years for RDPs, and 7.99 years for implant prosthesis, according to the evaluation with newly developed KAP criteria.