Retrospective clinical and radiological evaluation of the success rates of dental implants with different diameters

Aim: Dental implants are predominantly titanium structures placed into the jawbone to replace missing teeth and mimic the function of a tooth root. The success of implant therapy is fundamentally explained by the concept of osseointegration. In addition to recipient-site–related factors, implant-related characteristics have also been widely investigated as determinants of success. Among these, the effect of implant diameter is of particular importance. Narrow-diameter dental implants have been used to eliminate invasive and challenging procedures in narrow alveolar ridges or areas with critical anatomical limitations. Although there are studies investigating the success of narrow-diameter implants, the number of studies evaluating both clinical and radiographic outcomes together is limited. Moreover, examining the possible relationship between alveolar bone width and peri-implant marginal bone loss may also provide valuable insight. The aim of this study was to retrospectively evaluate the long-term clinical and radiographic success of narrow- and standard-diameter implants and to investigate the effect of alveolar ridge width on marginal bone level changes around narrow-diameter implants. Materials and Methods:This retrospective study included a total of 171 implants (87 narrow-diameter and 84 standard-diameter) placed between 2019 and 2023 at Bezmialem Vakıf University. The two implant groups were compared in terms of clinical and radiographic success criteria. Cone-beam computed tomography (CBCT) scans obtained preoperatively and panoramic radiographs taken immediately after surgery and at least two years postoperatively were evaluated. Marginal bone levels and buccolingual/palatal alveolar bone widths were measured on radiographs and CBCT images. During intraoral examinations, peri-implant probing depth, bleeding on probing, inflammation, mobility, and prosthesis fit were assessed. Patients were also asked to complete the OHIP-14 questionnaire. All measurements were performed 10 using Romexis software. Parametric statistical methods were used to analyze the data. Normality of continuous variables was assessed with the Shapiro–Wilk test and distribution plots, while homogeneity of variances was examined using Levene's test. Independent samples ttests were applied when normality and homogeneity assumptions were met; Welch's t-test was used when variances were unequal. Pearson's chi-square test was used for categorical variables. One-way ANOVA was used to evaluate bone loss variables according to prosthesis type within the narrow-diameter implant group. Pearson correlation coefficients were calculated to determine linear relationships between continuous variables. The significance level was set at .05, and analyses were performed using SPSS 27. Results: Statistical analysis revealed no significant difference between narrow- and standard-diameter implants regarding mesial and distal marginal bone loss at the end of the follow-up period (mesial: p = .261; distal: p = .742). In the narrow-diameter implant group, preoperative buccolingual/palatal alveolar ridge width ranged from 2.72 to 8.40 mm (N = 67), with a mean width of 5.59 mm (SD = 1.34) and a median of 5.49 mm. No correlation was found between preoperative buccolingual/palatal alveolar bone width and marginal bone level changes in narrow implants (r(67) = .006, p = .964)( (r =-.178 ve .006). Descriptive statistics for peri-implant probing depths showed a mean value of 2.31 mm (SD = 0.85). No significant differences were observed between the two groups regarding peri-implant inflammation, bleeding, mobility, or prosthesis fit. OHIP-14 scores indicated high levels of patient satisfaction and oral health–related quality of life. Conclusion: Within the limitations of this study, narrow-diameter implants demonstrated clinical and radiographic success comparable to standard-diameter implants, with no significant difference in peri-implant marginal bone loss between the two groups. Clinical intraoral findings also supported the success of narrowdiameter implants. Correlation analysis showed no relationship between buccolingual/palatal alveolar ridge width and medium to long-term marginal bone level changes. A total of 171 implants with at least 2-year and an average of 34- month follow-up were evaluated. The results suggest that narrow-diameter implants can be safely and reliably used in cases with insufficient ridge width or anatomical limitations, achieving success rates 11 similar to standard-diameter implants. With appropriate case selection, narrowdiameter implants may reduce or eliminate the need for extensive augmentation procedures, offering a less invasive and more predictable surgical alternative. Keywords: Narrow-diameter implants, standard-diameter implants, marginal bone loss, buccolingual/palatal alveolar ridge width, implant success, peri-implant tissue health, OHIP.