The objectives were to evaluate the bone loss (BL) around narrow diameter implants (3.3 mm) 2 years after implant loading and compare with the bone loss around conventional-diameter implants (4.1 mm), as well as with clinical and anatomical variables. 2-years follow-up. Cases: 20 patients either gender-age, narrow implants (Straumann TM-SLA, diameter 3.3 mm); Control: 20 patients matching for gender-age, conventional implants (Straumann TM-SLA, diameter 4.1). Total 82 implants (31 narrow implants and 51 conventional implants) in 40 patients. To avoid statistical bias, a cluster of one implant per patient was randomly selected (20 narrow implants and 20 conventional implants). To evaluate changes resulting from bone loss around the implants, a total of 80 panoramic radiographs were taken of all 40 patients; the first panoramic image was taken at the time of implant loading and the second one 2 years later. Clinical and demographic variables were obtained from the patients? medical records. Statistical method: Spearman?s correlation coefficient, chi-squared (Haberman?s post hoc), Mann-Whitney U and Kruskal-Wallis tests. Statistical significance p< 0.05. No significant differences in bone loss around were found around narrow implants versus conventional implants. Differences linked to tobacco use were found after studying one implant per patient (p< 0.05). With the limitations of the present study, no significant differences in BL were found when comparing narrow implants with conventional implants after 2 years of implant loading. There were also no differences found when accounting for other demographic and clinical variables, with the exception of tobacco use
