In recent years, treatment using implants has become common. Since 2016, dental implants have been insured as part of strengthening health insurance coverage. Consequently, the demand for implants is increasing. Accordingly, the importance of implant maintenance has been emphasized. Of which, implant retrievability is an important factor in implant success. Although the screw-retained type is an advantageous easy-to-retrieve prosthesis, an occlusal point cannot make it to the central axis of the implant. Thus, we aimed to introduce an implant setting method (screw hole indexing) that enables the maintenance of the proper occlusal point and enables retrievability by marking the screw holes of the implant.

Attrition is the loss of tooth hard tissue due to contact between teeth, and in severe cases, dentin is exposed, accompanied by selective corrosion and excessive wear of teeth, which is called cupping. If these lesions are left untreated, the size of the lesion gradually increases, breaking the unsupported enamel, resulting in a decrease in aesthetics and chewing function. In this case report, patients with cupping and enamel fracture due to severe attrition were directly restored using a resin with soft properties containing organic fillers. In the follow-up observation six years later, most of the filling of the occlusal surface was eliminated, but the filling on the buccal surfaces remained relatively intact, and it was confirmed that this type of resin was suitable for the area where the occlusal force was relatively weak rather than the area where the occlusal force was greatly applied.

Maxillary bone defects may follow surgical treatment of benign and malignant tumors, trauma, and infection. Palatal defects often lead to problems with swallowing and pronunciation from the leakage of air into the nasal cavity and sinus. Obturators have been commonly used to solve these problems, but long-term use of the device may cause irritation of the oral mucosa or damage to the abutment teeth. Utilizing implants in the edentulous area for the fabrication of the obturators has gained attention. This case report describes a patient, who had undergone partial resection of the maxilla due to adenocarcinoma, in need of a new obturator after losing abutment teeth after long-term use of the previous obturator. Implants were placed in strategic locations, and an implantretained maxillary obturator was fabricated, showing satisfactory results in the rehabilitation of multiple aspects, including palatal defect, masticatory function, swallowing, pronunciation, and aesthetics.

Dental implants are accepted as an effective treatment tools; however, they have a biomechanically disadvantageous structure compared with natural teeth. To compensate for the structural limitations of dental implants, occlusal must be considered to minimize the stress applied to the implants. This study aimed to verify whether the basic biomechanical principle that stress should be applied along the long axis of the implant fixture could be appropriately applied to actual implant clinical treatment. To evaluate whether the major axis of the implant is located at the center of the occlusion surface, the location of the screw hole was analyzed using the image of the stereolithographic file formed during the digital laboratory process, and the accuracy of implant placement was confirmed indirectly.The study included 261 patients and 392 implant cases. By tooth type, the numbers of samples were 57 in the first premolar, 66 in the second premolar, 152 in the first molar, and 117 in the second molar. The location of the screw hole was analyzed by dividing the occlusion surface of the implant crown into nine grids of the same size based on the outermost boundary. Consequently, the accuracy of implant placement tended to decrease from the premolar to the molar, upper jaw to the lower jaw, and left to right.

PURPOSE: In this study, the retrospective radiographic study is executed to evaluate amount of bone loss of various conditions in patients using customized abutment for 4 years of follow-up. MATERIALS AND METHODS: The subjects of this study were implant fixed dental prosthesis using CAD/CAM customized abutments. CAD/CAM customized abutment and fixed dental prosthesis were manufactured by the Prosthodontics Department of Chosun University Dental Hospital from August 1, 2011 to July 31, 2012. Radiological assessments were performed on the patients who were treated by the fixed prosthodontics. After each treatment, a retrospective study was performed for a total of 4 years at 3 months, 6 months, 1 year, 2 years, 3 years, and 4 years. RESULTS: As a result of the study, the customized abutment using CAD/CAM showed less bone loss than the results of existing research. There was no statistically significant differences at alveolar bone loss between splinting group and non-splinting group (respectively 0.27 mm, 0.5 mm). Also, there were statistically significant differences at alveolar bone loss in mx. anterior, mx. posterior, mn. anterior and mn. posterior part (respectively 1.37 mm, 0.39 mm, 0.00 mm, 0.30 mm). CONCLUSION: The customized abutment using CAD/CAM showed less bone loss than the results of existing research, there were statistically significant differences at alveolar bone loss in implant positions.
Alveolar Bone Loss ; Dental Prosthesis ; Follow-Up Studies ; Humans ; Prosthodontics ; Retrospective Studies ; Splints

Recently, flexible denture is widely used with some advantages such as esthetics, flexibility and biocompatibility. However, there is an opposite opinion about stability because of the movement of denture by the material's flexibility. As the denture moves to tissue surface during mastication, it irritates the supporting tissue. It can lead to trauma and rapid resorption of residual ridges if this irritation lasts for a long time. In this case, the patient has used flexible denture with insufficient stability, retention and support for several years and thus continuous irritation of the supporting tissue resulted in palate bone exposure. The patient discomfort and palate bone exposure underwent improvements by the new denture with stability and retention. A careful case selection for flexible denture, regular checkup and proper treatment are necessary to prevent the side effects.
Dentures* ; Esthetics ; Humans ; Mastication ; Palate* ; Pliability

PURPOSE: This study was performed to compare the stress distribution pattern of abutment-fixture connection area using 3-dimensional finite element model analysis when 5 different implant systems which have internal connection. MATERIALS AND METHODS: For the analysis, a finite element model of implant was designed to locate at first molar area. Stress distribution was observed when vertical load of 200 N was applied at several points on the occlusal surfaces of the implants, including center, points 1.5 mm, 3.0 mm away from center and oblique load of 200 N was applied 30degrees inclined to the implant axis. The finite element model was analyzed by using of 3G. Author (PlassoTech, California, USA). RESULTS: The DAS tech implant (internal step with no taper) showed more favorable stress distribution than other internally connected implants. AS compare to the situations when the loading was applied within the boundary of implants and an oblique loading was applied, it showed higher equivalent stress and equivalent elastic strain when the loading was applied beyond the boundary of implants. Regardless of loading condition, the abutments showed higher equivalent stress and equivalent elastic strain than the fixtures. CONCLUSION: When the occlusal contact is afforded, the distribution of stress varies depending on the design of connection area and the location of loading. More favorable stress distribution is expected when the contact load was applied within the diameter of fixtures and the DAS tech implant (internal step with no tapering) has more benefits than the other design of internally connected implants.
4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid ; Axis, Cervical Vertebra ; Bite Force ; California ; Dental Implants ; Finite Element Analysis ; Molar ; Sprains and Strains

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 +/- 67.55 N, 599.00 +/- 15.80 N, 588.20 +/- 33.18 N, and 97.83 +/- 98.13 N, 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.
Crowns

For the success of complete denture, three essential requirements such as retention, stability and support are needed. Moreover, due to the absorption of residual ridge and scarring due to the surgery, when making a complete denture, which is difficult to form the mandibular lingual margins, various considerations such as the arrangement of the Non-anatomical dl non-anatomical teeth, the polished surface impression, the internally weighted metal framework and the use of the denture adhesive cream are necessary. In this case report, the patient has a severely resorbed edentulous ridge from severe periodontitis and has some soft tissue problems after the glossectomy due to tongue cancer. To obtain additional retention and stability, some trials such as polished surface impression taking, internally weighted metal insertion and minimal pressure impression were done for the better result. Moreover To make a metal framework that precisely shapes the desired three-dimensional shape and reduces the complicated process, minimal pressure impression method and direct metal laser sintering technique were used.
Absorption ; Adhesives ; Cicatrix ; Denture, Complete ; Dentures ; Glossectomy ; Humans ; Methods ; Periodontitis ; Tongue Neoplasms ; Tooth

PURPOSE: Aims to analyze the occlusal wear patterns in maxillary posterior teeth with palatal side abfractions and study the association between occlusal force and abfractions. MATERIALS AND METHODS: This study was conducted in a total of 308 teeth from 148 patients with palatal side abfractions in maxillary posterior teeth. The occlusal wears in maxillary premolars and molars with palatal side abfractions were classified and recorded. The classification was done by type of teeth, age, and gender, and in order to evaluate the statistical significance between groups, chi-square test was conducted (α = 0.05). RESULTS: Palatal side abfractions in maxillary posterior teeth were observed at the highest frequency in the 1st molars, and in all teeth with palatal side abfractions, more than one occlusal wear was observed. In classification by type of teeth, by age, and by gender, the occlusal wears in teeth with palatal side abfractions were observed at high frequency in cuspal inclined plane, central fossa, and marginal ridge, and there was a statistical significance (P < 0.05). CONCLUSION: Palatal side abfractions were observed at the highest frequency in maxillary 1st molars, and in all maxillary posterior teeth where palatal side abfractions were found, the occlusal wears were observed. And the occlusal wears were observed at high frequency in cuspal inclined plane, central fossa and marginal ridge. Such results show that abfraction is associated with occlusal force.
Bicuspid ; Bite Force ; Classification ; Humans ; Molar ; Tooth Attrition ; Tooth Fractures ; Tooth