Effect of irrigation and stainless steel drills on dental implant bed heat generation

Bone Healing Evaluation Following Different Osteotomic Techniques in Animal Models: A Suitable Method for Clinical Insights

Osteotomy is a common step in oncological, reconstructive, and trauma surgery. Drilling and elevated temperature during osteotomy produce thermal osteonecrosis. Heat and associated mechanical damage during osteotomy can impair bone healing, with consequent failure of fracture fixation or dental implants. Several ex vivo studies on animal bone were recently focused on heating production during osteotomy with conventional drill and piezoelectric devices, particularly in endosseous dental implant sites. The current literature on bone drilling and osteotomic surface analysis is here reviewed and the dynamics of bone healing after osteotomy with traditional and piezoelectric devices are discussed. Moreover, the methodologies involved in the experimental osteotomy and clinical studies are compared, focusing on ex vivo and in vivo findings.

Surgical Drill Bit Design and Thermomechanical Damage in Bone Drilling: A Review

As drilling generates substantial bone thermomechanical damage due to inappropriate cutting tool selection, researchers have proposed various approaches to mitigate this problem. Among these, improving the drill bit design is one of the most feasible and economical solutions. The theory and applications in drill design have been progressing, and research has been published in various fields. However, pieces of information on drill design are dispersed, and no comprehensive review paper focusing on this topic. Systemizing this information is crucial and, therefore, the impetus of this review. Here, we review not only the state-of-the-art in drill bit designs-advances in surgical drill bit design-but also the influences of each drill bit geometries on bone damage. Also, this work provides future directions for this topic and guidelines for designing an improved surgical drill bit. The information in this paper would be useful as a one-stop document for clinicians, engineers, and researchers who require information related to the tool design in bone drilling surgery.

The effects of repeated usage of implant drills on cortical bone temperature, primary/secondary stability and bone healing: A preclinical in vivo micro-CT study

OBJECTIVE

The aims of the study were to evaluate the effects of new vs. used drills on cortical bone temperature, operation time, and primary/secondary stability and to assess bone healing by micro-CT.

MATERIALS AND METHODS

New, 50×-used and 100×-used drills at 800 rpm were used to place implants in the iliac crests of three male sheep in this experimental in vivo animal study. A total of 36 implants (12 in each group) were placed. The temperature of the cortical bone was recorded with an infrared thermometer, and the ISQ values at implant placement (primary stability) and at 4 weeks (secondary stability) were evaluated. The bone volume assessed by micro-CT was used to evaluate bone tissue healing. The results were statistically compared.

RESULTS

The results have shown that the operation time and the cortical bone temperature increased by the usage of the drills (p < .05) and the primary/secondary stability (ISQ values) decreased with the number of drill usage (p < .05) The highest 2- and 3-dimensional bone volume (assessed by micro-CT) were noted for new drills group followed by 50×-used drills and 100×-used drills (p < .05 at 4 weeks).

CONCLUSION

The number of drill usage seems to be directly affecting the osseointegration process in implant surgery. Therefore, replacing the drills at certain time intervals may increase the success of implant treatment.

Influence of an Alternative Implant Design and Surgical Protocol on Primary Stability

The purpose of thisin vitrostudy was to evaluate the influence of a new proposal of implant design and surgical protocol on primary stability in different bone densities. Four groups were tested (n=9): G1 - tapered, cone morse, Ø 4.3 mm x 10 mm in length (Alvim CM); G2 - experimental tapered; G3 - cylindrical, cone morse, Ø 4.0 mm x 11 mm in length (Titamax CM) and G4 - experimental cylindrical. The experimental implants were obtained from a design change in the respective commercial models. The insertion was performed in polyurethane (PU) blocks 0.24 g/cm3(20 pcf) and 0.64 g/cm3(40 pcf), according to different surgical protocols. The primary stability was measured by means of insertion torque (IT) and pullout test. Data were analyzed by ANOVA, Tukey's test (α=0.05) and Pearson's correlation. For IT and pullout, conventional and experimental implants showed no difference between them when inserted in the 20 pcf PU (p>0.05). In the 40 pcf PU, the modified implants exhibited greater IT (p<0.05) and lower pullout (p<0.05) compared to the respective conventional models. The implant design tested associated with the surgical protocol, positively influenced primary stability in higher density bones.

Comparative Analysis of the Chemical Composition and Microstructure Conformation Between Different Dental Implant Bone Drills

Background: Hardness is considered an important parameter for evaluating the clinical performance of dental implant bone drills. It is connected to the chemical composition, microstructure conformation and manufacture of the surgical drills. Methods: Microstructure of five dental implant drills using scanning electronic microscopy (SEM) integrated with energy dispersive X-ray spectrometry. Vickers microhardness was measured using a CV 2000 microhardness tester with an indentation force of 500 g. Results: Composition of the implant drills was typical of martensitic stainless steel (MSS). The drills contained 13%–17% of Cr; Mo, Si and Mn were present as minor ligands. The examined bone drills showed different external surface conformation and hardness in relation to the different industrial production processes. A rougher external surface and a higher hardness value are characteristics of the surgical bone drills produced by hot forming; the implant drills produced by machining showed mailing lines on their external surface and a lower hardness. Conclusions: Different compositions and treatments were used by the manufacturers to improve the hardness of the external layer of the dental implant drills making them prone to a diverse heat generation during the implant site preparation.

Recommended Drilling Parameters of Tungsten Carbide Round Drills for the Most Optimal Bone Removals in Oral Surgery

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.

Experimental and finite element analysis of surgical drill bits with and without irrigation channel - A case study approach

The aim of this study was to perform a finite element and experimental comparative analysis of the mechanical characteristics of surgical drill bits used in bone and joint surgery applications with and without an irrigation channel. Internally cooled drills are very efficient in maintaining the drilling temperature below the critical level. However, a cooling channel could potentially have a negative influence on the drill structure, particularly in the flutes zone. A commercially available type of surgical drill bit without irrigation channel and a modified variant with the built-in channel were simultaneously loaded with torque, axial and bending forces with magnitudes similar to and higher than those utilized in clinical practice. When loaded under the same conditions, both types of drills showed very similar mechanical properties in the sense of the average von Mises stress in chosen sections and the deflections after plastic deformation. The highest stress was observed in the bending zone which was located at the beginning of the flutes section of the drill. All analysed drills suffered only from plastic deformation without any breakage despite the fact that they were loaded with forces higher than those expected in normal operational conditions.

The effects of irrigation volume to the heat generation during implant surgery

Background

To evaluate the effects of the amount of irrigation on heat generated during implant site preparation.

Material and Methods

Ten freshly dissected sheep mandibles were sectioned into 30 equal bone blocks and transferred into a heat-controlled water tank. Implant socket preparations were performed with four consecutive drills. Temperature measurements were performed with a thermocouple inserted into the bone immediately before the preparation and after the drilling using three different physiologic saline irrigation set-ups: 1- No irrigation, 2- 12 ml/min and 3- 30 ml/min irrigation volume. The temperature differences between three different irrigation set-ups for implant drills 1, 2, 3 and 4, and the temperature differences between the drills for three different irrigation set-ups were separately compared.

Results

The temperature difference of no irrigation group was significantly higher than 12 ml/min and 30 ml/min groups for all four drills (p<0.05), whereas no statistically significant difference was found between 12 ml/min and 30 ml/min irrigation groups. (P >0.05) The temperature difference of drill 1 is significantly higher than drills 2, 3 and 4 for no irrigation group. (P <0.05) The temperature differences of drill 1, 2 and 3 were significantly higher than the temperature difference of drill 4 for 12 ml/min irrigation group. (p<0.05).

Conclusions

The heat generated during drilling is not directly proportional to the coolant volume. Given that certain amount of irrigation is applied, implant sites can be prepared safely without the need for additional irrigation, which may result in reduced visibility of the surgical site and therefore a suboptimal surgery.

Key words:Dental implants, irrigation, heat generation, drilling.