• The Journal of Advanced Prosthodontics
• /
• v.10 no.5
• /
• pp.388-394
• /
• 2018

PURPOSE. To measure axial displacement of different implant-abutment connection types and materials during screw tightening at the recommended torque by using a contact scanner for two-dimensional (2D) and three-dimensional (3D) analyses. MATERIALS AND METHODS. Twenty models of missing mandibular left second premolars were 3D-printed and implant fixtures were placed at the same position by using a surgical guide. External and internal fixtures were used. Three implant-abutment internal connection (INT) types and one implant-abutment external connection (EXT) type were prepared. Two of the INT types used titanium abutment and zirconia abutment; the other INT type was a customized abutment, fabricated by using a computer-controlled milling machine. The EXT type used titanium abutment. Screws were tightened at $10N{\cdot}cm$, simulating hand tightening, and then at the manufacturers' recommended torque ($30N{\cdot}cm$) 10 min later. Abutments and adjacent teeth were subsequently scanned with a contact scanner for 2D and 3D analyses using a 3D inspection software. RESULTS. Significant differences were observed in axial displacement according to the type of implant-abutment connection (P<.001). Vertical displacement of abutments was greater than overall displacement, and significant differences in vertical and overall displacement were observed among the four connection types (P<.05). CONCLUSION. Displacement according to connection type and material should be considered in choosing an implant abutment. When adjusting a prosthesis, tightening the screw at the manufacturers' recommended torque is advisable, rather than the level of hand tightening.

• The Journal of Korean Academy of Prosthodontics
• /
• v.57 no.1
• /
• pp.57-65
• /
• 2019

Computer aided design and manufacturing and implant surgery using a guide template improve restoration-driven implant treatment procedures. This case utilized those digital technologies to make definitive prostheses for a patient. According to the work flow of digital dentistry, cone beam computed tomography established the treatment plan, which was followed to make the guide template for implant placement. The template guided the implants to be installed as planned. The customized abutments and surveyed fixed restorations were digitally designed and made. The metal framework of the removable partial denture was cast from resin pattern using an additive manufacturing technique, and the artificial resin teeth were replaced with the zirconia onlays for occlusal stability. These full mouth rehabilitation procedures provided functionally and aesthetically satisfactory results for the patient.

• Journal of Periodontal and Implant Science
• /
• v.41 no.5
• /
• pp.227-233
• /
• 2011

Purpose: The aim of this study was to compare osteoblast behavior on zirconia and titanium under conditions cultured with bone morphogenetic protein-2. Methods: MC3T3-E1 cells were cultured on sandblasted zirconia and sandblasted/etched titanium discs. At 24 hours after seeding MC3T3-E1, the demineralized bone matrix (DBM) gel alone and the DBM gel with bone morphogenetic protein-2 (BMP-2) were added to the culture medium. The surface topography was examined by confocal laser scanning microscopy. Cellular proliferation was measured at 1, 4, and 7 days after gel loading. Alkaline phosphatase activity was measured at 7 days after gel loading. The mRNA expression of ALPase, bone sialoprotein, type I collagen, runt-related transcription factor 2 (Runx-2), osteocalcin, and osterix were evaluated by real-time polymerase chain reaction at 4 days and 7 days. Results: At 1, 4, and 7 days after loading the DBM gel alone and the DBM gel with BMP-2, cellular proliferation on the zirconia and titanium discs was similar and that of the groups cultured with the DBM gel alone and the DBM gel with BMP-2 was not significantly different, except for titanium with BMP-2 gel. ALPase activity was higher in the cells cultured with BMP-2 than in the other groups, but there was no difference between the zirconia and titanium. In ALPase, bone sialoprotein, osteocalcin, Runx-2 and osterix gene expression, that of cells on zirconia or titanium with BMP-2 gel was much more highly increased than titanium without gel at day 7. The gene expression level of cells cultured on zirconia with BMP-2 was higher than that on titanium with BMP-2 at day 7. Conclusions: The data in this study demonstrate that the osteoblastic cell attachment and proliferation of zirconia were comparable to those of titanium. With the stimulation of BMP-2, zirconia has a more pronounced effect on the proliferation and differentiation of the osteoblastic cells compared with titanium.

• Journal of the Korean Ceramic Society
• /
• v.48 no.2
• /
• pp.152-159
• /
• 2011

The green and hard machining characteristics of dental ceramics are of great interest to dental industry. The green bodies of TZP/$Al_2O_3$ composites were prepared by the cold isostatic pressing, and machined on the CNC lathe using PCD (polycrystalline diamond) insert under various machining conditions. With increasing nose radius of PCD insert, surface roughness initially increased due to increased cutting resistance, but decreased by the onset of sliding fracture. The lowest surface roughness was obtained at spindle speed of 1,300 rpm and lowest feed rate. Hard bodies were prepared by pressureless sintering the machined green bodies at several temperatures. The grinding test for sintered hard body was conducted using electroplated diamond bur with different grit sizes. During grinding, grain pull out in the composite was occurred due to thermal expansion mismatch between the alumina and zirconia. The strength of the composite decreased with alumina contents, due to increased surface roughness and high monoclinic phase transformed during grinding process. The final polished samples represented high strength by the elimination of a phase transformation layer.

• The Journal of Advanced Prosthodontics
• /
• v.3 no.2
• /
• pp.85-89
• /
• 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
• /
• v.53 no.4
• /
• pp.345-351
• /
• 2015

Purpose: The purpose of this study was to evaluate the proper axial thickness of zirconia abutment applied to implant in the anterior region. Materials and methods: Zirconia abutments were prepared at different axial wall thickness by processing pre-sintered zirconia blocks via CAD/CAM to obtain equal specimens. The abutments were each produced with a thickness of 0.5 mm (Group 1), 0.8 mm (Group 2), 1.2 mm (Group 3), or 1.5 mm (Group 4). The implant used in this study was a external connection type one (US, Osstem, Pussan, Korea) product and the zirconia abutment was prepared via replication of a cemented abutment. The crowns were prepared via CAM/CAM with a thickness of 1.5 mm and were cemented to the abutments using $RelyX^{TM}$ UniCem cement. A universal testing machine was used to apply load at 30 degrees and measure fracture strength of the zirconia abutment. Results: Fracture strength of the abutments for Group 1, Group 2, Group 3, and Group 4 were $236.00{\pm}67.55N$, $599.00{\pm}15.80N$, $588.20{\pm}33.18N$, and $97.83{\pm}98.13N$, respectively. Group 1 showed a significantly lower value, as compared to the other groups (independent Mann-Whitney U-test. P<.05). No significant differences were detected among Group 2, Group 3, and Group 4 (independent Mann-Whitney U-test. P>.05). Conclusion: Zirconia abutment requires optimal thickness for fracture resistance. Within the limitation of this study, > 0.8 mm thickness is recommended for zirconia abutment in anterior implants.

• The Journal of Korean Academy of Prosthodontics
• /
• v.57 no.3
• /
• pp.245-253
• /
• 2019

Orthognathic surgery of skeletal Class III malocclusion improves oral function and facial appearance. The greater amount of skeletal discrepancy, the greater amount of teeth movement required for decompensation, and this often causes pathological changes in periodontal tissue especially in lower anterior dentition. We made a Top-Down treatment plan with personalized analysis using Face Hunter, Plane System and ARCUS Digma II, in order to resolve severe mobility and cross-bite of lower anterior teeth for 49-year-old female patient who had undergone orthognathic surgery 20 years ago due to skeletal Class III malocclusion and mandibular prognathism. Lower anterior teeth were extracted and alveoloplasty was done. After healing of the wound, immediate loading was conducted immediately after implant placement. Final restorations were fabricated Zirconia using CAD/CAM, and inserted intraorally screw-retained type. During 6-month follow-up, no abnormal episodes of restorations were observed, and obtained satisfactorily both of functional and esthetic outcomes.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.39 no.4
• /
• pp.237-249
• /
• 2023

Orofacial dystonia is a neuromotor disorder that causes irregular or repetitive movements of the face, lips, tongue, and jaw involuntarily, also called tic disorder. Edentulous patients with these symptoms experience functional and aesthetic problems, including difficulty using complete dentures, speech and swallowing difficulties, and orofacial pain. In this case, for a patient with orofacial dystonia who experienced complete edentulism at a relatively young age, restorative treatment was performed with a maxillary complete denture with bilateral posterior zirconia occlusal surfaces and a mandibular implant-supported fixed prosthesis, and continuous smile training was performed. The aim was to improve the aesthetics of facial muscles. As a result of the treatment, the patient was very satisfied with not only improved chewing function and aesthetics, but also regained psychological stability and was able to lead a normal daily life, so we would like to report this.

• The Journal of Korean Academy of Prosthodontics
• /
• v.56 no.4
• /
• pp.354-359
• /
• 2018

In a single implant restoration of maxillary anterior teeth, it is difficult to accomplish an aesthetic restoration of the implant prosthesis in the case of gingival recession and bone defect problems. To maintain aesthetic stability in the long term, it is important to place the implant in the ideal position as well as the recovery of the soft tissue and harmony with the prosthesis. Not only ideal implant position but also the harmony with surrounding soft tissues are important to fabricate aesthetic implant prosthesis for these cases. for these cases, a 47- years -old male with lowered level of osseous crest and gingival recession on maxillary anterior tooth was treated with guided bone regeneration and gingival recontouring.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.1
• /
• pp.48-54
• /
• 2019

PURPOSE. The aim of the present randomized controlled study was to compare prefabricated all-ceramic, anatomically shaped healing abutments followed by all-ceramic abutments and all-ceramic crowns and prefabricated standard-shaped (round-diameter) titanium healing abutments followed by final titanium abutments restored with porcelain-fused-to-metal (PFM) implant crowns in the premolar and molar regions. MATERIALS AND METHODS. Forty-two patients received single implants restored either by all-ceramic restorations (test group, healing abutment, final abutment, and crown all made of zirconia) or conventional titanium-based restorations. Immediately after prosthetic incorporation and after 12 months of loading, implant survival, technical complications, bone loss, sulcus fluid flow rate (SFFR) as well as plaque index (PI) and implant stability (Periotest) were analyzed clinically and radiologically. RESULTS. After 12 months of loading, an implant and prosthetic survival rate of 100% was observed. Minor prosthetic complications such as chipping of ceramic veneering occurred in both groups. No statistical significant differences were observed between both groups with only a minimum of bone loss, SFFR, and PI. CONCLUSION. All-ceramic implant prostheses including a prefabricated anatomically shaped healing abutment achieved comparable results to titanium-based restorations in the posterior region. However, observational results indicate a benefit as shaping the peri-implant soft-tissue with successive provisional devices and subsequent compression of the soft tissue can be avoided.