Complication rates for various retention types in anterior implant-supported prostheses: A retrospective clinical study.

STATEMENT OF PROBLEM: Implant-supported prostheses have typically been retained by cement or screws, each of which has advantages and disadvantages. Two new types of prosthesis with complementary advantages and disadvantages have been proposed: the screw- and cement-retained prosthesis, which combines cement and screw retention, and the antiloosening inner-post screw (ALIPS) type, which uses lateral screws. Both esthetic and functional factors should be considered for anterior prostheses; however, clinical studies of the complication rates of these designs are lacking. PURPOSE: The purpose of this retrospective clinical study was to evaluate the complications of dental implant-supported restorations with various prosthetic types in the anterior region and to analyze other factors that affect complications. MATERIAL AND METHODS: This study included 51 patients who had 83 implants placed in the anterior region by a single clinician between August 2009 and December 2016. Surgical and prosthetic features were recorded, and implant complications were analyzed. RESULTS: There were 45 (55.4%) cement-retained implants, 5 (6.0%) screw- and cement-retained prosthesis implants, and 32 (38.6%) ALIPS-retained implants. Peri-implant mucositis was observed most frequently in the ALIPS type (21.9%), but the biological complications did not differ significantly with the prosthetic type. The most common mechanical complication was loss of retention in the cement type of prosthesis (30.4%) and screw loosening in the ALIPS type (43.8%). Implant complications varied with position (maxilla or mandible) and implantation timing (period from tooth extraction to implant placement). CONCLUSIONS: The complications of implants placed in the anterior region were affected by different factors but did not differ significantly with the type of the retention.

The prosthetic abutment height can affect marginal bone loss around dental implants.

BACKGROUND: Marginal bone loss (MBL) is considered an important determinant of implant success, and establishing the peri-implant biological width has been regarded to influence MBL around implants. However, few studies have attempted to show the relationship between the crown/abutment gap and MBL. PURPOSE: To evaluate the effect of the prosthetic abutment height on MBL of dental implants. MATERIALS AND METHODS: This study evaluated data which were retrospectively collected through chart and panoramic radiographs of 145 patients (78 males and 67 females; aged 19 to 79 years, mean age 54.1 years) in whom 273 implants were placed by a single clinician between June 2009 and December 2014. The abutment height and the bone level were measured in digital panorama radiographs. All correlations between abutment height and MBL were analyzed using Spearman's test (P < .05). RESULTS: The 273 implants comprised 126 in 67 female patients and 147 in 78 male patients. The mean age of the patients was 54.1 years (range 19-79 years). The prevalence of MBL and the mean MBL decreased as the abutment height increased. Spearman's test showed a significant negative correlation between abutment height and MBL (P < .05). CONCLUSION: The present study suggests that implants with a higher prosthetic abutment show less MBL, with the abutment height recommended to not exceed 4 mm.