Influence of bone density, drill diameter, drilling speed, and irrigation on temperature changes during implant osteotomies: an in vitro study

Correlation between intraosseous thermal change and drilling impulse data during osteotomy within autonomous dental implant robotic system: An in vitro study

OBJECTIVES

This study aims at examining the correlation of intraosseous temperature change with drilling impulse data during osteotomy and establishing real-time temperature prediction models.

MATERIALS AND METHODS

A combination of in vitro bovine rib model and Autonomous Dental Implant Robotic System (ADIR) was set up, in which intraosseous temperature and drilling impulse data were measured using an infrared camera and a six-axis force/torque sensor respectively. A total of 800 drills with different parameters (e.g., drill diameter, drill wear, drilling speed, and thickness of cortical bone) were experimented, along with an independent test set of 200 drills. Pearson correlation analysis was done for linear relationship. Four machining learning (ML) algorithms (e.g., support vector regression [SVR], ridge regression [RR], extreme gradient boosting [XGboost], and artificial neural network [ANN]) were run for building prediction models.

RESULTS

By incorporating different parameters, it was found that lower drilling speed, smaller drill diameter, more severe wear, and thicker cortical bone were associated with higher intraosseous temperature changes and longer time exposure and were accompanied with alterations in drilling impulse data. Pearson correlation analysis further identified highly linear correlation between drilling impulse data and thermal changes. Finally, four ML prediction models were established, among which XGboost model showed the best performance with the minimum error measurements in test set.

CONCLUSION

The proof-of-concept study highlighted close correlation of drilling impulse data with intraosseous temperature change during osteotomy. The ML prediction models may inspire future improvement on prevention of thermal bone injury and intelligent design of robot-assisted implant surgery.

A novel technique to harvest bone autografts with mild local hyperthermia and enhanced osteogenic bone quality: a preclinical study in dogs

BACKGROUND

Guided bone regeneration (GBR) involves collecting bone autografts with high bio-quality and efficiency. The current non-irrigated low-speed drilling has been limited for broader application in bone autograft harvest due to its low efficiency, inability to conduct buccal cortical perforation, and dependence on simultaneous implant placement. Increasing the drilling speed helps improve the efficiency but may incur thermal-mechanical bone damage. Most studies have addressed thermal reactions during bone drilling on non-vital models, which is irrelevant to clinical scenarios. Little has been known about bone's in vivo thermal profiles under non-irrigated higher-speed drilling and its influences on the resulting bone chips.

AIM

A novel technique for bone harvest and cortical perforation via in-situ non-irrigated higher-speed drilling was proposed and investigated for the first time.

METHODS

The third mandible premolars of eight beagles were extracted and healed for three months. Sixteen partial edentulous sites (left and right) were randomized into four groups for bone autograft harvest without irrigation: chisel, 50 rpm drilling, 500 rpm drilling, and 1000 rpm drilling. Bone chips were harvested on the buccal plates of the missing tooth. An infrared camera and an implantable thermocouple collaboratively monitored in vivo real-time bone temperature at the drilling sites. In vitro performances of cells from bone chips, including cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, mRNA transcriptional level of osteogenic genes and heat shock protein 70 (HSP-70), and HSP-70 expression at the protein level were also studied.

RESULTS

500 rpm produced mild local hyperthermia with a 2-6 °C temperature rise both on the cortical surface and inside the cortical bone. It also held comparable or enhanced cell performances such as cell number, viability, proliferation, migration, ALP activity, in vitro mineralization, and osteogenic genes expression.

CONCLUSIONS

In-situ non-irrigated higher-speed drilling at 500 rpm using a screw drill is versatile, efficient, and thermal friendly and improves the bio-quality of bone chips. Our novel technique holds clinical translational potential in GBR application.

Biomechanical comparison of compact versus standard flute drill bits, and interlocking versus buttress thread self-tapping cortical bone screws in cadaveric equine third metacarpal condyle

OBJECTIVES

To compare (1) performance of compact versus standard flute drill bits, (2) screw insertion properties and (3) pullout variables between interlocking thread (ITS) and buttress thread (BTS) self-tapping screws in third metacarpi.

STUDY DESIGN

In vitro experimental study.

SAMPLE POPULATION

Paired third metacarpi from 11 Thoroughbreds aged 2-4 years.

METHODS

Screws were inserted into the lateral condylar fossae following bone preparation using the respective drill bit for each screw type. Screw pullout was achieved using a mechanical testing system. Density and porosity of bone surrounding screw holes was measured with microcomputed tomography following each pullout test. Drilling, screw insertion and pullout variables were compared between drill bit and screw types using repeated measures ANOVA. Linear regression analyses were used to characterize relationships between bone tissue properties and drill bit and screw outcomes.

RESULTS

Maximum torque power spectral density (PSD) was lower for compact flute drill bits. Insertion torque was 50% higher for ITS. BTS had 33% greater preyield stiffness and 7% greater mean yield force. Bone tissue properties affected measured variables similarly for both screw and drill bit types.

CONCLUSIONS

Lower torque PSD may increase durability of the compact flute drill bit. ITS had greater insertional torque, which may reflect greater bone engagement. BTS had greater resistance to axial pullout forces.

CLINICAL SIGNIFICANCE

Metacarpal bone provides a simple model for comparison of drill bit and screw designs. Use of ITS to repair equine fractures subject to predominantly tensile forces is not justified based on the results of this study.

Influence of Surgical Technique on Post-Operative Complications in the Extraction of the Lower Third Molar: A Retrospective Study

The surgical extraction of the impacted third molar is frequently associated with several complications. The purpose of this study is to assess how two different surgical protocols affect post-operative complications during the extraction of the lower impacted third molars. In order to compare and evaluate two different techniques (triangular flap vs. envelope flap), and the relative post-extraction complications, two groups of 150 patients each underwent to surgical impacted third molar extraction and 60 days of follow-up. The complication rate in the two groups was 14.00% in group A and 17.33% in group B. There was a strong association between smoking (OR: 2.8) and the use of oral contraceptives (OR: 1.75) with complications. The age- and sex-related incidence of complications in hard tissue healing has great variability in the literature; the analysis performed on our data did not show a statistically significant association between them. Even though related to a higher incidence of transient changes in sensitivity, it was found that the envelope flap saw a lower percentage of complications. There is still no clarity on which is the best protocol for the extraction of the lower impacted third molar, and the choice often depends on the surgeon's experience.

Does Saline Irrigation at Different Temperatures Affect Pain, Edema, and Trismus After Impacted Third Molar Surgery: A Clinical Trial

PURPOSE

Lower impacted third molar surgery is a very common oral-maxillofacial surgical procedure, which has complications such as facial swelling, pain, and trismus. This clinical trial aimed to compare the intensity of postoperative morbidity (pain, facial swelling, and trismus) following the third molar surgery performed using saline irrigation at different temperatures (4 °C, 10 °C, or 25 °C).

MATERIALS AND METHODS

This double-blind, single-center, split-mouth, randomized prospective clinical trial was conducted among 48 systemically and periodontally healthy patients who had bilaterally asymptomatic mandibular third molars. Patients were randomly allocated into 2 groups (n = 24) according to the temperature of the saline used. In each patient, one impacted third molar was determined as the test group (4 °C or 10 °C saline irrigation) and the other impacted third molar as the control group (25 °C saline irrigation). Trismus and swelling were evaluated on the 1^st, 3^rd, and 7^th days postoperatively. Pain perception by visual analog scale (VAS) and the total number of analgesics taken during the 7 postoperative days were recorded. Data were analyzed using the Shapiro-Wilk test, the chi-square test, one-way analysis of variance, Duncan test, the Kruskal-Wallis test, the Dunn test, and the Friedman test (P < .05).

RESULTS

Forty-eight patients (28 females, 20 males) with a mean age of 24.6 ± 3.8 years were included in the study. The duration of operations was similar. VAS values of test groups [test group 1 (4 °C): 4.0, test group 1 (10 °C): 8.0] and the number of analgesics taken [test group 1 (4 °C): 0, test group 1 (10°) C): 3] were significantly lower (P < .001) than control groups (VAS, control group 1: 13.0, control group 2: 15.5, number of analgesic taken, control group 1: 5.5, control group 2: 4.0). Significant differences were found between the test groups in VAS values and the number of analgesics taken (P < .001). Also, the lowest trismus and facial swelling values were detected in the 4 °C test group at all time points (P < .001).

CONCLUSION

In the impacted third molar surgery, the use of cooled saline irrigation during bone removal may be a simple, inexpensive, and effective method for reducing early postoperative complaints.

Temperature Changes during Implant Osteotomy Preparations in Human Cadaver Tibiae Comparing MIS® Straight Drills with Densah® Burs

(1) Background: Several studies showed a sustained temperature of 47 °C or 50 °C for one minute resulted in vascular stasis and bone resorption with only limited bone regrowth over a 3-4-week healing period. The purpose of the present study was to evaluate the temperature changes (ΔΤ) that occur during the preparation of dental implant osteotomies using MIS^® straight drills versus Densah^® burs in a clockwise (cutting) drilling protocol. (2) Methods: Two hundred forty (240) osteotomies of two different systems' drills were prepared at 6 mm depth at 800, 1000, and 1200 revolutions per minute (RPM), in fresh, unembalmed tibiae, obtained by a female cadaver. ΔΤ was calculated by subtracting the baseline temperature on the tibial surface, from the maximum temperature-inside the osteotomy (ΔT = T_max - T_base). The variables were evaluated both for their individual and for their synergistic effect on ΔΤ with the use of one-, two-, three- and four-way interactions; (3) Results: An independent and a three-way interaction (drill design, drill width, and RPM) was found in all three RPM for the Densah^® burs and at 1000 RPM for the MIS^® straight drills. As Densah^® burs diameter increased, ΔΤ decreased. The aforementioned pattern was seen only at 1000 RPM for the MIS^® straight drills. The usage of drills 20 times more than the implant manufacturers' recommendation did not significantly affect the ΔΤ. A stereoscopic examination of the specimens confirmed the findings. (4) Conclusions: The independent and synergistic effect of drills' diameter, design and RPM had a significant effect on ΔΤ in human tibiae, which never exceeded the critical threshold of 47 °C.

Effect of process parameters on the temperature changes during robotic bone drilling

In medical surgery, bone drilling is an inevitable procedure. The thermal necrosis in the drilling process can affect post-operative recovery. In this study, the method of drill bit precooling is proposed in bone drilling with robot assisted system. The influence of process parameters on the drilling temperature were investigated and analyzed. The results showed that the method of drill bit precooling could reduce the drilling temperature. The drill bit starting temperature and the feed rate were more important parameters on the drilling temperature compared with rotational speed and cooling length of the drill bit. The quadratic regression model obtained from response surface experiments can predicted the drilling temperature correctly under the range of process parameters in this study. The optimal parameter combination is rotational speed = 1610 rpm, feed rate = 0.5 mm/s, the starting temperature of drill bit = 8°C, and the cooling length = 34.8 mm. The results provide an effective method to reduce thermal necrosis of bone cells in drilling.

Effects of a simplified drilling protocol at 50 rpm on heat generation under water-free conditions: an in vitro study

PURPOSE

In recent years, guided implant surgery has been widely used for the convenience of patients and surgeons. Further streamlining the surgical procedure would make implant surgery more convenient. Low-speed water-free conditions are often used in guided implant surgery. Therefore, in this study, we attempted to confirm once again whether drilling was safe at a low speed without water. The main purpose of this study was to evaluate whether a simplified drilling protocol that omits some intermediate steps in the drilling process was safe from the viewpoint of heat generation.

METHODS

D1 density artificial bone blocks were drilled under 50 rpm, 10 N·cm water-free conditions, and the surface temperature was measured using a digital infrared camera. First, drilling was performed with the sequential drilling method, which is the most widely used technique. Second, for each drill diameter, the temperature change was measured while performing simplified drilling with omission of the previous 1, 2, or 3 steps.

RESULTS

In sequential drilling, the heat generated during drilling at all diameters was less than the critical temperature of osteonecrosis (47°C) except for the ⌀2 drill. Statistical significance was observed in all groups when comparing sequential and simplified drilling in the ⌀3.2, ⌀3.8, and ⌀4.3 drills (P<0.001). However, in the simplified drilling procedures, the temperature was below the osteonecrosis threshold temperature (47°C) except for the ⌀4.3 drill with the omission of the previous 3 steps (⌀3.0, ⌀3.2, and ⌀3.8).

CONCLUSIONS

In general, drilling under low-speed, water-free conditions has shown stable results in terms of heat generation. Simplified drilling showed statistically significantly greater heat generation than sequential drilling. However, most of the diameters and omitted steps seem to be clinically acceptable, so it will be useful if an appropriate selection is made according to the patient's clinical condition.

Precision and trueness of computer-assisted implant placement using static surgical guides with open and closed sleeves: An in-vitro analysis

Objectives

The aim of this in vitro study was to determine accuracy defined by trueness and precision of computer‐assisted implant surgery comparing two guided surgery kits designed for either closed sleeves or open sleeves with a lateral window.

Material and methods

Each n=20 implants were placed fully guided (sleeve‐bone distance of 2 or 4 mm) in identical replicas using a surgical guide with both closed sleeve or an open sleeve, partially guided, or free hand. The achieved implant position was digitized and compared with the planned position. Trueness and precision were determined. The angular deviation was defined as the primary outcome parameter. The means, standard deviation, and 95%‐confidence intervals were analyzed statistically with 1‐way ANOVA and the Scheffé procedure.

Results

The accuracy of guided implant placement using closed and open sleeves was comparable when the sleeve‐bone distance was 2 mm. Accuracy decreased when the sleeve‐bone distance increased in both fully guided groups, more so in the open than in the closed sleeve group. The least accurate method was the free‐hand group. Partially guided implant surgery was more accurate than free‐hand placement, but less accurate than the fully guided groups with 2‐mm sleeve‐bone distance.

Conclusions

The closer the sleeve to the bone, the more accurate and precise is computer‐assisted implant surgery using a closed system and a system using open sleeves. Partially guided implant surgery using only the static guide for the pilot drill is less accurate than both fully guided approaches, but more accurate than free‐hand surgery.

THE KEY RESEARCH OF SPORTS IN MAINTAINING HUMAN HEALTH

ABSTRACT Introduction One of the evaluation factors of human health is bone health, and an evaluation index of bone health is osteoporosis. Sports are an effective way to improve the human body. Objective The paper discusses the effects of different exercise intensities on human bone health. Methods The thesis selected 51 female college students, designed different exercise intensities of fitness running intervention programs, and conducted a 12-month exercise intervention. We divide female college students into three groups. The subjects’ bone mineral density (BMD), serum alkaline phosphatase (ALP), and serum osteocalcin (BGP) were tested before and after the experiment. Results The differences in femoral BMD, serum ALP, serum BGP, and lumbar spine BMD of the three groups of volunteers were significant (P<0.05), while the differences in ulna and radius BMD were not significant. Conclusions Sports can promote human bone health. At the same time, the effect of fitness running on human BMD is site-specific. Level of evidence II; Therapeutic studies - investigation of treatment results.

Low-speed drilling without irrigation versus conventional drilling for dental implant osteotomy preparation: a systematic review

PURPOSE

This paper aims to review the evidence comparing low-speed drilling without irrigation versus conventional drilling for dental implant osteotomy preparation.

MATERIALS AND METHODS

A systematic review was carried out based on the PRISMA statement. Four databases and gray literature were searched up to November 2020. In vitro, animal, and clinical studies were included. The variables were temperature change, drilling time, quantity of harvested bone, osteotomy precision, marginal bone loss, implant success rate, osseointegration, and the histomorphologic characteristics and cellularity of the osteotomy and of the harvested bone. Different tools for the assessment of bias were applied for each study design.

RESULTS

A total of 626 articles were identified, of which 13 were included. Both low-speed drilling without irrigation (test group) and conventional drilling (control group) maintained temperatures below the critical temperature of 47 °C. The test group yielded a greater quantity and more beneficial cellular and histomorphologic properties of harvested bone, with a longer drilling time and greater osteotomy precision (p < 0.05). No significant results were obtained regarding drill wear, osseointegration, marginal bone loss, implant success rate, and histomorphology of the dental implant osteotomy (p > 0.05). The results, in particular on the osteotomy precision and quantity of harvested bone chips, should be interpreted with caution because outcomes are based in only one in vitro study.

CONCLUSIONS

Low-speed drilling without irrigation seems to be comparable to conventional drilling in preparing dental implant osteotomies. In some situations, low-speed drilling without irrigation might offer advantages over conventional drilling. The results should be interpreted with caution due to the low percentage of clinical human studies. Accordingly, more clinical studies are needed to improve the scientific evidence on this topic.

CLINICAL RELEVANCE

The low-speed drilling without irrigation is a valid technique for dental implant osteotomy preparation. Its higher quantity and quality of harvested autologous bone might be particularly beneficial in cases of dental implant placement with minor simultaneous bone regeneration.

Intra-osseous heat generation during implant bed preparation with static navigation: Multi-factor in vitro study

OBJECTIVES

To compare the intra-osseous temperature reached during bone drilling for dental implant placement using open versus closed static surgical guides and evaluate the influence of bone density, osteotomy drilling depth, and irrigation fluid temperature.

MATERIAL AND METHODS

960 osteotomies were performed with 2 mm pilot drills in 16 solid rigid polyurethane foam blocks. Two main variables were considered: the guide type (open or closed guide) and bone density (hard (D1) or soft (D4). The blocks were divided into four groups according to the type of surgical template and bone density as follows: group one: closed guide and hard bone; group two: open guide and hard bone; group three: closed guide and soft bone; and group four: open guide and soft bone. A combination of different experimental conditions was used, including different bone osteotomy depths (6 or 13 mm) and irrigation fluid temperatures (5°C or 21°C).

RESULTS

The highest mean temperature was found in group one (28.29 ± 4.02°C). In the soft bone groups (three and four), the mean maximum temperature decreased compared to groups one and two (dense bone) and was always higher with closed guides (23.38 ± 1.92°C) compared to open guides (21.97 ± 1.22°C) (p < .001). The osteotomy depth and irrigation fluid temperature also significantly influenced the bone temperature (p < .001), especially in hard bone.

CONCLUSIONS

The greatest heat generation was observed in high-density bone. The final intra-bone temperature was about 1°C higher with a closed static surgical guide than with an open guide. The heat generation in osteotomy sites was substantially reduced by cooling the irrigation fluid to 5°C.