• Journal of Periodontal and Implant Science
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• v.48 no.3
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• pp.182-192
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• 2018

Purpose: The purpose of the present study was to validate an experimental model for assessing tissue integration of titanium and zirconia implants with and without buccal dehiscence defects. Methods: In 3 dogs, 5 implants were randomly placed on both sides of the mandibles: 1) Z1: a zirconia implant (modified surface) within the bony housing, 2) Z2: a zirconia implant (standard surface) within the bony housing, 3) T: a titanium implant within the bony housing, 4) Z1_D: a Z1 implant placed with a buccal bone dehiscence defect (3 mm), and 5) T_D: a titanium implant placed with a buccal bone dehiscence defect (3 mm). The healing times were 2 weeks (one side of the mandible) and 6 weeks (the opposite side). Results: The dimensions of the peri-implant soft tissue varied depending on the implant and the healing time. The level of the mucosal margin was located more apically at 6 weeks than at 2 weeks in all groups, except group T. The presence of a buccal dehiscence defect did not result in a decrease in the overall soft tissue dimensions between 2 and 6 weeks ($4.80{\pm}1.31$ and 4.3 mm in group Z1_D, and $4.47{\pm}1.06$ and $4.5{\pm}1.37mm$ in group T_D, respectively). The bone-to-implant contact (BIC) values were highest in group Z1 at both time points ($34.15%{\pm}21.23%$ at 2 weeks, $84.08%{\pm}1.33%$ at 6 weeks). The buccal dehiscence defects in groups Z1_D and T_D showed no further bone loss at 6 weeks compared to 2 weeks. Conclusions: The modified surface of Z1 demonstrated higher BIC values than the surface of Z2. There were minimal differences in the mucosal margin between 2 and 6 weeks in the presence of a dehiscence defect. The present model can serve as a useful tool for studying peri-implant dehiscence defects at the hard and soft tissue levels.

• The Journal of Advanced Prosthodontics
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• v.10 no.2
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• pp.79-84
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• 2018

PURPOSE. All-ceramic restorations required extensive tooth preparation. The purpose of this in vitro study was to investigate a minimally invasive preparation and thickness of monolithic zirconia crowns, which would provide sufficient mechanical endurance and strength. MATERIALS AND METHODS. Crowns with thickness of 0.2 mm (group 0.2, n=32) or of 0.5 mm (group 0.5, n=32) were milled from zirconia and fixed with resin-based adhesives (groups 0.2A, 0.5A) or zinc phosphate cements (groups 0.2C, 0.5C). Half of the samples in each subgroup (n=8) underwent thermal cycling and mechanical loading (TCML)(TC: $5^{\circ}C$ and $55^{\circ}C$, $2{\times}3,000cycles$, 2 min/cycle; ML: 50 N, $1.2{\times}10^6cycles$), while the other samples were stored in water ($37^{\circ}C/24h$). Survival rates were compared (Kaplan-Maier). The specimens surviving TCML were loaded to fracture and the maximal fracture force was determined (ANOVA; Bonferroni; ${\alpha}=.05$). The fracture mode was analyzed. RESULTS. In both 0.5 groups, all crowns survived TCML, and the comparison of fracture strength among crowns with and without TCML showed no significant difference (P=.628). Four crowns in group 0.2A and all of the crowns in group 0.2C failed during TCML. The fracture strength after 24 hours of the cemented 0.2 mm-thick crowns was significantly lower than that of adhesive bonded crowns. All cemented crowns provided fracture in the crown, while about 80% of the adhesively bonded crowns fractured through crown and die. CONCLUSION. 0.5 mm thick monolithic crowns possessed sufficient strength to endure physiologic performance, regardless of the type of cementation. Fracture strength of the 0.2 mm cemented crowns was too low for clinical application.

• Imaging Science in Dentistry
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• v.52 no.3
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• pp.267-273
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• 2022

Purpose: The aim of this study was to assess the influence of kilovoltage- peak (kVp) and the metal artifact reduction (MAR) tool on the detection of buccal and lingual peri-implant dehiscence in the presence of titanium-zirconia (Ti-Zr) and zirconia (Zr) implants in cone-beam computed tomography (CBCT) images. Materials and Methods: Twenty implant sites were created in the posterior region of human mandibles, including control sites (without dehiscence) and experimental sites (with dehiscence). Individually, a Ti-Zr or Zr implant was placed in each implant site. CBCT scans were performed using a Picasso Trio device, with variation in the kVp setting (70 or 90 kVp) and whether the MAR tool was used. Three oral radiologists scored the detection of dehiscence using a 5-point scale. The area under the receiver operating characteristic (ROC) curve, sensitivity, and specificity were calculated and compared by multi-way analysis of variance (α=0.05). Results: The kVp, cortical plate involved (buccal or lingual cortices), and MAR did not influence any diagnostic values (P>0.05). The material of the implant did not influence the ROC curve values(P>0.05). In contrast, the sensitivity and specificity were statistically significantly influenced by the implant material (P<0.05) with Zr implants showing higher sensitivity values and lower specificity values than Ti-Zr implants. Conclusion: The detection of peri-implant dehiscence was not influenced by kVp, use of the MAR tool, or the cortical plate. Greater sensitivity and lower specificity were shown for the detection of peri-implant dehiscence in the presence of a Zr implant.

• Journal of the Korean Academy of Esthetic Dentistry
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• v.22 no.1
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• pp.9-21
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• 2013

Aesthetics means differ from cultures and times and also differ from each person's own thinking. But as a restorative dentist who works for esthetic areas, we need to have certain principles and rationale. Some functions in CAD/CAM looks very useful to match harmonious shape to adjacent teeth and also very effective and efficient when compare to the traditional laboratory technics. Also we will discuss about link abutment (Titanium-Zirconia abutment) which we need for dental implant placed anterior area where the soft tissue is thin.

• Restorative Dentistry and Endodontics
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• v.43 no.1
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• pp.9.1-9.6
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• 2018

The objective of this case report is to introduce a simple technique for simultaneously taking a closed-mouth impression and functionally generated path (FGP) for a full coverage crown restoration. A monolithic zirconia crown was the restoration of choice. An alginate impression of the abutment tooth was taken to fabricate a custom-made closed-mouth impression tray covering the abutment tooth and the adjacent teeth. The tray had an FGP table and an abutment tray in cameo and intaglio surfaces, respectively. The impression was taken with silicone impression material after adjusting the abutment tray and inscribing the FGP using self-curing acrylic resins. Plaster casts were made from the impression, and a zirconia crown was fabricated. The crown was cemented to the abutment tooth with minimal adjustments. This simple technique resulted in a well-fitting crown that accounted for mandibular movements. Using the custom closed-mouth impression tray incorporating an FGP table simultaneously aids in fabricating an accurately fitting restoration that incorporates harmonious mandibular movements using a single impression capture.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.61-69
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• 2020

Purpose: Zirconia fixed partial dentures with mandibular 2^nd premolar and 2^nd molar as abutments are fabricated and then the effects of inter-abutment distance on fracture resistance of zirconia fixed partial dentures is studied. Materials and Methods: The materials used in this study are Cameleon S zirconia block and S2 zirconia block, which are divided into CS Group and S2 Group applying different inter-abutment distance for each material, and the sintered zirconia fixed partial denture was luted to the epoxy resin die using a temporary luting cement, and then the fracture resistance was measured by placing a 6 mm diameter hardened steel ball on the occlusal surfaces of the pontics and applying pressure at a cross head speed of 1.0 mm/min on a universal testing machine with a load cell of 5.0 kN. Results: The fracture resistance of zirconia fixed partial dentures is not significantly affected by inter-abutment distance The fracture resistance of zirconia fixed partial dentures in CS Group was significantly higher in 15 mm of inter-abutment distance than in 13 mm and 17 mm of inter-abutment distance (P < 0.05). The fracture resistance of zirconia fixed partial dentures in S2 Group was not significantly different between the three groups (P > 0.05). Conclusion: The fracture resistance of zirconia fixed partial dentures with mandibular 2^nd premolar and 2^nd molar as abutments does not significantly affected by the inter-abutment distance.

• The Journal of Korean Academy of Prosthodontics
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• v.55 no.2
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• pp.156-163
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• 2017

People with class I intellectual disability need lifelong assistance and protection from their surroundings due to impaired adaptive functioning. They have poor oral health and show higher prevalence of dental caries, periapical inflammation and tooth loss that require proper prosthetic restoration. Because removable prostheses for intellectually disabled patients often lack stability, retention, and maintenance, fixed prostheses are essential and the only available option is dental implants. In this case, a 45 year-old male patient with class I intellectual disability had poor oral hygiene with most of his teeth missing and visited the clinic to recover his masticatory function. Due to such systemic conditions, the definitive restoration of choice was the implant-supported fixed dental prosthesis made of biocompatible and highly strong monolithic zirconia. In consequence of the treatment process, the patient was able to improve his oral environment aesthetically and functionally.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.111-123
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• 2006

A Study on the Fracture Strength of All-Ceramic Crown according to the Zirconia Coping Design using CAD/CAM System L. Bulgan, In-Ho Cho, Soo-Yeon Shin Department of Prosthodontics, Graduate School, Dankook University The fracture strength of prosthesis is important, because it affects the function, and long term success of prosthesis and teeth. The purpose of this study was to compare the fracture strength of zirconia coping designs. Experimental test group were classified into three designs according to coping design, Modified design: Zirconia coping margin was located at 1mm above the axiogingival line angle. Collarless design: The coping margin terminated at the axiogingival line angle Butt design: The coping margin was extended to the finishing line of prepared margin. A $Cercon^{(R)}$(Degussa, Germany) CAD/CAM system was used to make the zirconia coping. Fracture strength was measured using loading machine at a cross head speed of 1mm/min. The results were statistically analyzed using the one-way ANOVA and multiple comparison test. Statistical significance was set in advance at the probability level of less than 0.05. The result : I. Collarless($738N{\pm}155N$) and Modified($755N{\pm}185N$) groups showed significantly a lower fracture strength than Butt($1057N{\pm}262N$) group(p<0.05). II. There were no statistical differences of the fracture strength between Modified($755N{\pm}185N$) and Collarless($738N{\pm}155N$) groups. III. When comparing the fractured surface, all the group showed porcelain fracture, which were fractured at the labial surface of baked porcelain The butt design of the zirconia coping has higher fracture strength than modified and collarless design.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.444-450
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• 2014

PURPOSE. To compare the accuracy of marginal and internal adaptation of zirconia (Zr) copings fabricated on anatomic (A), semi-anatomic (SA) and non-anatomic (NA) occlusal surface preparations. MATERIALS AND METHODS. 45 extracted bicuspid teeth were prepared for receiving zirconia crowns, with different occlusal preparation designs A=15, SA=15 & NA=15. The Zr copings were fabricated by using CAD4DENT, CAD/CAM. The copings were adjusted, cemented and were cross sectioned centrally from buccal cusp tip to lingual cusp tip into mesial and distal halves. The copings were examined under electron microscope at ${\times}200$ magnification and the measurements were recorded at 9 predetermined areas in micrometers. RESULTS. Overall mean gap values for the three groups was found to be $155.93{\pm}33.98{\mu}m$ with Anatomical Occlusal preparation design having the least gap value of $139.23{\pm}30.85{\mu}m$ showing the best adaptation among the groups. Post Hoc Tukey's test showed a statistically significant difference (P=.007) between the means of gap for A & NA preparation designs. Measurements recorded at 9 predetermined points showed variations for the three groups. CONCLUSION. Anatomical occlusal preparation designs resulted in better marginal and internal adaptation of Zr copings. There is a considerable variation between the measured marginal and internal gap values for the Zr copings fabricated by the (CAD4DENT-CAD/CAM). This variation may be associated with the lack of standardization of the preparation of teeth, computerized designing of the coping for each tooth, cement used, uniform pressure application during the cementation of the copings, sectioning of the copings and the microscopic measurements.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.3
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• pp.293-300
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• 2022

Various materials and restorative options have been introduced recently with growing interest in esthetic dental treatment in modern society. Zirconia is especially known for its biocompatibility as well as remarkable toughness and resistance to wear, but it is limited in its use for esthetically focused treatment in anterior region for its white opacity. Lately the development of different kinds of zirconium blocks, such as colored block, clear block, and multi-layered block, allowed more extensive use of zirconia as a treatment option. This report describes a case, in which a prosthetic crown maxillary anterior region was stained with a combination of various coloring liquids before sintering to reproduce natural-looking color scheme in final restoration. The case was reported as the utilization of coloring liquid on monolithic zirconia crown could achieve esthetically satisfying prosthesis for both dentist and patient.