Abstract
Background High temperatures during drilling can cause thermal osteonecrosis and abnormal wound healing. According to our best knowledge, a widely accepted recommendation for optimal drilling parameters in routine oral surgery bone removals does not exist. Purpose Our aim was to investigate the correlations of different drilling parameters, including axial load and revolution speed on drilling temperatures and preparation times. Materials and Methods Standard, 5 mm deep cavities were drilled in 20 PCF (lb/ft3) dens polyurethane blocks with 3 mm (50PCF) cortical layer using new and worn, 3.1mm in diameter tungsten carbide round drills. Worn drills were used in 50 impacted third molar operations before. Axial loads of 3N, 10N, and 25N and speeds of 4.000-8.000-16.000-40.000 revolutions per minute (rpm) were tested. Temperature differences of drilling parameters were calculated by 1-way ANOVA, followed by Tukey's HSD post hoc tests. Time differences and differences among “optimal” and “suboptimal” groups (with the cut-off value of 3°C and 3s) were estimated by Kruskal-Wallis test with pairwise comparisons. P<0.05 was considered significant. Results The highest mean temperatures with new and worn drills were 4.64±0.53°C and 6.89±1.16°C, while drilling times varied between 0.16±0.02s and 22.77±5.45s. A 3°C and 3s cut-off value classified drillings significantly to (1) optimal [3N and 8000-16000-40000 rpm or 10N and 4000-8000-16000-40000 rpm] or suboptimal due to (2) high temperatures or (3) long preparation times. Using worn drills, the following parameters should be avoided: 3N with 4.000-8.000 rpm, 10N with 40000 rpm, and 25N at any revolutions. Discussion The study extensively mapped the drilling temperatures and preparation times of tungsten carbide round drills. Temperatures did not exceed 10°C during drillings with maximal amount of cooling, as well as the drilling parameters, which kept temperatures and preparation times in the most optimal range which were clearly established.
Highlights
Bone removal is an important step in several oral surgical procedures
Excessive intraosseous heat production can lead to thermal osteonecrosis, which strongly influences the wound healing and regeneration mechanisms, and may lead, e.g., to alveolitis [1, 2]
In the case of worn drills, the significantly highest temperature increases for each of the examined axial load values were seen at 40000 rpm
Summary
Bone removal is an important step in several oral surgical procedures. The most optimal bone removal is fast and painless and does not disturb normal healing processes. According to Blum (2002), the incidence of alveolitis can be 25-30% after third molar removals, where drilling is a very frequent procedure [3]. According to our best knowledge, a widely accepted recommendation for optimal drilling parameters in routine oral surgery bone removals does not exist. Our aim was to investigate the correlations of different drilling parameters, including axial load and revolution speed on drilling temperatures and preparation times. A 3∘C and 3s cut-off value classified drillings significantly to (1) optimal [3N and 8000-1600040000 rpm or 10N and 4000-8000-16000-40000rpm] or suboptimal due to (2) high temperatures or (3) long preparation times. The study extensively mapped the drilling temperatures and preparation times of tungsten carbide round drills. Temperatures did not exceed 10∘C during drillings with maximal amount of cooling, as well as the drilling parameters, which kept temperatures and preparation times in the most optimal range which were clearly established
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