Need for lateral bone augmentation at two narrow-diameter implants: A prospective, controlled, clinical study

Objectives: To detect the potential influence of implant diameter and anatomic factors on the need for bone augmentation procedures (BAPs) when replacing congenitally missing lateral incisors (MLIs).

Materials and methods: Patients with congenitally missing MLIs with a mesio-distal distance between the canine and the central incisor of 5.9-6.3 mm received a Ø2.9 mm implant while Ø3.3 mm implants were placed when the distance was 6.4-7.1 mm. The following linear measurements were recorded using a calliper: width of the alveolar process (WAP), width of the bony alveolar ridge (WAR) and thickness of the facial bone after implant osteotomy (TFB). Guided bone regeneration was performed in case of fenestration- or dehiscence-type defects or a thin TFB (<1.7 mm).

Results: Fifty Ø2.9 mm and 50 Ø3.3 mm were included in 100 patients. WAP and WAR did not differ between the groups (p > .05). TFB was statistically significant larger in the Ø2.9 group (1.75 ± 0.59 mm) compared to the Ø3.3 group (1.5 ± 0.63 mm) (p = .041). Fenestration-type defects (p = .005) and a thin facial bone wall (p = .045) was observed more frequently in the Ø3.3 compared to the Ø2.9 group. Correspondingly, BAP was indicated more frequently in the Ø3.3 compared to the Ø2.9 group (p = .017). WAP, MD and WAR were statistically significant correlated to the need for BAP (p < .001). As independent variable, only WAR influenced the probability of BAP (p < .001).

Conclusion: The use of 2.9 diameter implants was correlated to a reduced frequency of BAP compared to 3.3 mm implants, without reaching a statistically significant difference. Measurement of the WAP provides the clinician useful information to predict BAP.