• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.618-630
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• 2000

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiber-reinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements. ($Bistite\;II^(R),\;Super-bond^(R),\;Variolink\;II^(R)$), Zinc phosphate and Glass-Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of $5^{\circ}C\;and\;55^{\circ}C$ in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II($46.78{\mu}m$), Variolink II($56.25{\mu}m$), Super-Bond($56.78{\mu}m$), Glass-Ionomer($99.21{\mu}m$), Zinc Phosphate($109.49{\mu}m$) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.3
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• pp.253-268
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• 2012

Full-mouth reconstruction of a patient using dental implants is a challenge if there is vertical and horizontal bone resorption, since this includes the gingival area and restricts the position of the implants. however, hard- and soft-tissue grafting may allow the implants to be placed into the desired position. Although it is possible to regenerate lost tissues, an alternative is to use fixed detachable prostheses that restore the function and the esthetics of the gingiva and teeth. Various material combinations including metal/acrylic, metal/ceramic, and zirconia/ceramic have been used for constructing this type of restoration. Other problems include wear, separation or fracture of the resin teeth from the metal/acrylic prosthesis, chipping or fracture of porcelain from the metal/ceramic or zirconia/ceramic prosthesis, and fracture of the framework in some free-end prostheses. With virtually unbreakable, chip-proof, life-like nature, monolithic zirconia frameworks can prospectively replace other framework materials. This clinical report describes the restoration of a patient with complete fixed detachable maxillary and mandibular prostheses made of monolithic zirconia with dental implants. The occluding surfaces were made of monolithic zirconia, to decrease the risk of chipping or fracture. The prostheses were esthetically pleasing, and no clinical complications have been reported after two years.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.175-186
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• 2022

A crossed occlusion resulting from the presence of posterior teeth in one arch but no opposing teeth in the opposite arch results in collapse of the vertical dimension. In this case, the patient has a class III malocclusion with crossed occlusion and anterior crossbite. In order to evaluate the proper vertical dimension, provisional denture was used to stabilize the vertical occlusal dimension for 3 months. After, provisional fixed restoration was used for the stabilizing occlusal relationship and aesthetic improvement for lip support. Definitive prosthesis in implants in the mandible and abutments in the maxillary were using Porcelain-fused-to-metal crown (PFM) crown and the maxillary unilateral edentulous area was treated with removable partial dentures. Through this, proper support of the posterior region and normal anterior occlusal relationship were formed, and the patient was able to obtain aesthetically and functionally satisfactory treatment results.

• 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.3
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• pp.194-200
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• 2016

PURPOSE. The prospective follow-up aimed to assess the performance of lithium disilicate crowns and clinical reasons of adverse events compromising survival and quality. MATERIALS AND METHODS. 58 patients were treated with 375 heat-pressed monolithic crowns, which were bonded with resin cement. Annual recalls up to five years included a complete dental examination as well as quality assessment using CDA-criteria. Any need for clinical intervention led to higher complication rate and any failure compromised the survival rate. Kaplan-Meier-method was applied to all crowns and a dataset containing one randomly selected crown from each patient. RESULTS. Due to drop-outs, 45 patients (31 females, 14 males) with the average age of 43 years (range = 17-73) who had 327 crowns (176 anterior, 151 posterior; 203 upper jaw, 124 lower jaw) were observed and evaluated for between 4 and 51 months (median = 28). Observation revealed 4 chippings, 3 losses of retention, 3 fractures, 3 secondary caries, 1 endodontic problem, and 1 tooth fracture. Four crowns had to be removed. Survival and complication rate was estimated 98.2% and 5.4% at 24 months, and 96.8% and 7.1% at 48 months. The complication rate was significantly higher for root canal treated teeth (12%, P<.01) at 24 months. At the last observation, over 90% of all crowns showed excellent ratings (CDA-rating Alfa) for color, marginal fit, and caries. CONCLUSION. Heat pressed lithium disilicate crowns showed an excellent performance. Besides a careful luting, dentists should be aware of patients' biological prerequisites (grade of caries, oral hygiene) to reach full success with these crowns.

• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.317-325
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• 1995

This study was performed to investigate the mean life expectancy of dental prosthetic restorations. The author has examined 352 dental prosthesis clinically and radiologically, and decided the success(survival) and failure(mortality) of the dental prosthesis. The dental prosthesis which had been treated in the Seoul National University Dental Hospital, two private clinics in Seoul, one university dental hospital, and two private clinics in local province were included in this study. The survival analysis using product limit estimator was used and the mean life expectancy of each type of dental prosthesis was calculated. The results were as follows : 1. The life expectancies were 10.5 years in gold crown and bridge, 8.5 years in porcelain fused to metal crown and bridge, 8.3 years in nonprecious metal crown and bridge, 8.1 years in removal partial denture, and 7.7 years in full denture. 2. The causes of mortality were in the order of dental caries(24.6%), fracture of dental prosthesis(19.2%), periodontal problems(18.6%), chronic chewing difficulty and dysfunction due to dental prosthesis(15.0%), excessive exposure of abutments due to the marginal defect of dental prosthesis(14.4%), abnormal occlusion due to severe attrition of artificial teeth in dentures(3.0%), periapical problems(2.4%), perforation of dental prosthesis(1.8%), and loose contacts with neighboring tooth(1.2%). 3. Among survival cases, 66.5% showed normal chewing ability and 31.9% showed partial chewing ability. However, 1.6% of them complained loss of chewing ability. 4. Among failure cases, 6.6% showed normal chewing ability and 38.9% showed partial chewing ability. However, 54.5% of them complained loss of chewing ability.

• The Journal of Advanced Prosthodontics
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• v.3 no.2
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• pp.85-89
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• 2011

PURPOSE. The purpose of this study was to evaluate the amount of resorption and thickness of labial bone in anterior maxillary implant using cone beam computed tomography with Hitachi CB Mercuray (Hitachi, Medico, Tokyo, Japan). MATERIALS AND METHODS. Twenty-one patients with 26 implants were followed-up and checked with CBCT. 21 OSSEOTITE $NT^{(R)}$. (3i/implant Innovations, Florida, USA) and 5 $OSSEOTITE^{(R)}$. implants (3i/implant Innovations, Florida, USA) were placed at anterior region and they were positioned vertically at the same level of bony scallop of adjacent teeth. Whenever there was no lesion or labial bone was intact, immediate placement was tried as possible as it could be. Generated bone regeneration was done in the patients with the deficiency of hard tissue using $Bio-Oss^{(R)}$. (Geistlich, Wolhusen, Switzerland) and $Bio-Gide^{(R)}$. (Geistlich, Wolhusen, Switzerland). Second surgery was done in 6 months after implant placement and provisionalization was done for 3 months. Definite abutment was made of titanium abutment with porcelain, gold and zirconia, and was attached after provisionalization. Two-dimensional slices were created to produce sagittal, coronal, axial and 3D by using OnDemand3D (Cybermed, Seoul, Korea). RESULTS. The mean value of bone resorption (distance from top of implant to labial bone) was $1.32 \;{\pm}\; 0.86\; mm$ and the mean thickness of labial bone was $1.91 \;{\pm}\; 0.45 \;mm$. CONCLUSION. It is suggested that the thickness more than 1.91 mm could reduce the amount and incidence of resorption of labial bone in maxillary anterior implant.

• The Journal of Korean Academy of Prosthodontics
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• v.28 no.2
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• pp.199-215
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• 1990

This study was to analyze the stress distribution of implant and supporting tissue in $Br{\aa}nemark$ osseointegration implant. The analysis has been conducted by using the axisymmetric finite element method and type of model according to crown material. Tests have been performed at 1 kg load on central fossa of crown portion. Each type of model was designed differently according to crown material. 1) Porcelain fused to metal crown(Model A) 2) Composite resin veneered crown(Model B) 3) Acrylic resin veneered crown(Model C) 4) Type III gold crown(Model D) The displacements and stresses of implant and supporting structures were analyzed to investigate the influence of the type of crown material. The results were obtained as follows : 1. Displacement of implant was shown uniformly downward displacement in all models and abutments were observed distally downward displacement. 2. In supporting tissues, stress was concentrated on the crest of compact bone and the spongy bone below implant. 3. The PFM and the type III gold crown showed the largest concentration of stress at the crest of compact bone and the spongy bone below implant, respectively. Acrylic resin artificial teeth and composite resin veneered crown indicated almost the same distribution of stress. 4. The gold screw, the abutment screw and the top of abutment showed the concentration of stress in implants of every model.

• The Journal of Korean Academy of Prosthodontics
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• v.49 no.1
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• pp.80-86
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• 2011

When a tooth adjacent to implant has coronal damages caused by severe dental caries or fracture, the clinical crown lengthening by forced eruption makes it possible to get esthetic restoration due to the prevention of alveolar crestal bone resorption and loss of interdental papilla. A 54-years-old male patient wanted prosthetic treatment because his anterior 3 unit bridges had fallen out. A right maxillary central incisor showed mild dental caries but a right maxillary canine lost most clinical crowns. Forced eruption combined with a gingival fiberotomy of a right maxillary canine was performed for 1 month after the dental implant had been simultaneously placed with bone grafts on a right maxillary lateral incisor. About 5 months after implant placement, 2nd surgical operation was performed. The provisional restorations were adjusted to make esthetic gingival contour for 8 weeks. The porcelain fused gold restorations were fabricated and set. The patient was satisfied with the final restorations in esthetic and functional aspect.

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.181-188
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• 2020

PURPOSE. The effect of core design on the fracture resistance of zirconia-lithium disilicate (LS2) bilayered crowns for anterior teeth is evaluated by comparing with that of metal-ceramic crowns. MATERIALS AND METHODS. Forty customized titanium abutments for maxillary central incisor were prepared. Each group of 10 units was constructed using the same veneer form of designs A and B, which covered labial surface to approximately one third of the incisal and cervical palatal surface, respectively. LS2 pressed-on-zirconia (POZ) and porcelain-fused-to-metal (PFM) crowns were divided into "POZ_A," "POZ_B," "PFM_A," and "PFM_B" groups, and 6000 thermal cycles (5/55 ℃) were performed after 24 h storage in distilled water at 37 ℃. All specimens were prepared using a single type of self-adhesive resin cement. The fracture resistance was measured using a universal testing machine. Failure mode and elemental analyses of the bonding interface were performed. The data were analyzed using Welch's t-test and the Games-Howell exact test. RESULTS. The PFM_B (1376. 8 ± 93.3 N) group demonstrated significantly higher fracture strength than the PFM_A (915.8 ± 206.3 N) and POZ_B (963.8 ± 316.2 N) groups (P<.05). There was no statistically significant difference in fracture resistance between the POZ_A (1184.4 ± 319.6 N) and POZ_B groups (P>.05). Regardless of the design differences of the zirconia cores, fractures involving cores occurred in all specimens of the POZ groups. CONCLUSION. The bilayered anterior POZ crowns showed different fracture resistance and fracture pattern according to the core design compared to PFM.