One-wall proximal defects: pretreatment characteristics and bone response following flap curettage

Several characteristics of 53 infrabony defects were compared with changes in bone height, following treatment by flap-curettage and regular maintenance. The mean post-surgical interval was 11.4 years. Proximal angular defects from mandibular posterior teeth comprised the study population. Changes in bone height following therapy were compared with the pre-treatment bone loss, tooth-bone angle, and inter-radicular width. The influence of the post-surgical duration on these factors was also evaluated. Bone height was examined at both the deep and shallow sides of each proximal defect. Data were collected from enlarged tracings of pre- and post-treatment radiographs. Gain or loss of bone was established at greater than 2 SD of the measurement error as determined by replicate calibration trials. Deep-side sites which gained bone exhibited the most pretreatment bone loss at a mean of 57.1%. These sites also exhibited a mean tooth-bone angle of 31.9 degrees and a mean inter-radicular width of 3.1 mm. Gaining sites were those with longer post-surgical durations. Deep-side sites that lost bone following therapy had a mean pre-treatment bone loss of 43.6%, a mean tooth-bone angle of 50.3 degrees, and a mean interradicular width of 2.9 mm. Losing sites were those with shorter post-surgical durations. The majority of deep-side sites with less than 55% pretreatment bone loss remained unchanged. Shallow-side sites which gained bone following treatment had a greater mean pretreatment bone loss and a smaller tooth-bone angle than losing sites.

Relative stability of deep- versus shallow-side bone levels in angular proximal infrabony defects

The relative changes with time, in the position of the coronal margin of the mesial and distal bone of proximal, angular infrabony defects, were investigated. Tracings of the radiographs of 51 mandibular posterior sites, treated by flap curettage, with a mean post-surgical duration of 11.8 years, were measured using a digitizer pad. The group consisting of shallow-side sites (N = 51), exhibited no significant change in the bone height with time; however, there was a significant decrease in bone height in the deep-side group (N = 51). The mean area of proximal bone decreased significantly with time. The defects were divided into early (N = 25) and advanced (N = 26) angular groups, and then into deep- and shallow-side subgroups. In the early defect group, there was a significant decrease in the mean bone height of the deep-side subgroup. There were no differences in the changes of mean bone level of the remaining 3 subgroups with time. There was no correlation between changes in bone levels of adjacent mesial and distal sides of angular defects with time (r = 0.27). There was no difference between the deep- and shallow-side groups in the number of sites which gained, lost or evidenced no change in bone height. In the study population, the bone height of 73% of the deep-side, and 84% of the shallow-side sites was either unchanged or in a more coronal position.(ABSTRACT TRUNCATED AT 250 WORDS)