A radiographic comparison of progressive and conventional loading on crestal bone loss and density in single dental implants: a randomized controlled trial study

Abstract

Objective: Crestal bone loss is a biological complication in implant dentistry. The aim of this study was to compare the effect of progressive and conventional loading on crestal bone height and bone density around single osseointegrated implants in the posterior maxilla by a longitudinal radiographic assessment technique.

Materials and methods: Twenty micro thread implants were placed in 10 patients (two implants per patient). One of the two implants in each patient was assigned to progressive and the other to conventional loading groups. Eight weeks after surgery, conventional implants were restored with a metal ceramic crown and the progressive group underwent a progressive loading protocol. The progressive loading group took different temporary acrylic crowns at 2, 4 and 6 months. After eight months, acrylic crowns were replaced with a metal ceramic crown. Computer radiography of both progressive and conventional implants was taken at 2, 4, 6, and 12 months. Image analysis was performed to measure the height of crestal bone loss and bone density.

Results: The mean values of crestal bone loss at month 12 were 0.11 (0.19) mm for progressively and 0.36 (0.36) mm for conventionally loaded implants, with a statistically significant difference (P < 0.05) using Wilcoxon sign rank. Progressively loaded group showed a trend for higher bone density gain compared to the conventionally loaded group, but when tested with repeated measure ANOVA, the differences were not statistically significant (P > 0.05).

Conclusion: The progressive group showed less crestal bone loss in single osseointegrated implant than the conventional group. Bone density around progressively loaded implants showed increase in crestal, middle and apical areas.

Keywords: Dental Implant Loading; Dental Prosthesis; Implant-Supported.

Fig 1

Progressive loaded implant sequence, a: two months after surgery, the first temporary crown was placed in 2mm infraocclusion, b: four months after surgery, the second temporary crown was placed in 40μ occlusal contact, c: six months after surgery, the last temporary crown was placed into full occlusion (12μ occlusal contact), d: eight months after surgery, the last temporary crown was replaced by a cemented metal ceramic crown with the same occlusal contact.

Fig 2

To measure crestal bone loss, implant shoulder on the mesial (a) and distal (c), the first contact of the alveolar crestal bone to the implant on the mesial (b) and distal (d) the apex of the implant (e) and the middle of the implant shoulder (f) were marked

Fig 3

To measure the change on bone density around the implant, nine 1mm² regions-of-insert (ROI) were considered. Immediately apical to the bone-implant contact on the mesial and distal area of the implant (A,H), in the middle of micro-thread on the mesial and distal area of the implant (B,G), on the contact of micro-thread to the macro-thread on the mesial and distal area of the implant (C,F), the apical area of the implant at the mesial and distal of the implant (D, E), the last ROI was placed on the body of the implant in the distal shoulder (Ref)