Aim: The present study aimed to evaluate the clinical measurements and radiographic marginal bone loss of narrow and regular platform dental implants with the TiUnite surface placed in the posterior jaws.Material and Methods: The study was designed as a retrospective, parallel, longitudinal pilot trial.Twenty-eight patients (mean age: 48.34 ± 6.06) and 66 TiUnite surfaces bone level dental implants (Nobel Biocare Parallel Conical Connection) were included in the study.The implants were divided into two different groups according to the narrow platform implants (NPIs) (n=32) and regular platform implants(RPIs) (n=26).The mean implant lengths, plaque index (PI), gingival index (GI), periodontal pocket depth (PD), gingival recession (GR), keratinized gingival width (KGW) and bleeding on probing (BOP) values were recorded.Mean marginal bone level (MBL) values were evaluated, in which the distance between the bone-implant contact and the implant shoulder reference points was assessed on digital periapical radiographs via a software program (Mediadent Software).The Student's t-test was used for between-group comparison.Trial registration: NCT04572490.Retrospectively registered, (available at: https://clinicaltrials.gov/ct2/show/NCT04572490).Results: The mean MBL value was 0.84±0.81mm in the NPIs group and 0.44±0.65 mm in the RPIs group.Regarding the radiological evaluations, there was a statistically significant difference between the groups in the mean MBL (p<0.05).F(3)+6.56,p<0.001 and the GR value of 41% of the variance in the dependent variable predict mean MBL positively and significantly in the NPI group.Discussion: Within the limitations, in this study group, narrow-platform TiUnite surface conical connection dental implants showed a higher rate of gingival recession and, consequently, marginal bone loss was observed at a higher rate in the long follow-up period.