In-vitro experimental study of histopathology of bone in vibrational drilling

Impact of drill bit wear on temperature increase in dental implant osteotomy: an in vitro study

OBJECTIVES

Dental implant surgery relies extensively on bone drilling, a critical procedure with intrinsic challenges. Drill bits show significant wear and are frequently utilized beyond the manufacturer's recommended limits. Such practices can result in adverse effects, including friction and temperature rise in the surrounding bone area during interventions, with an increased risk of necrosis that can compromise the dental implant osseointegration. This study aimed to compare the quality of osteotomy obtained from two different protocols to determine a possible correlation between the drilling temperature and the tool wear and to evaluate their impact on potential health damage.

MATERIALS AND METHODS

Experimental evaluations were conducted using synthetic bone that reproduced human bone characteristics. The drilling phase involved real-time temperature acquisition and scanning electron microscopy analysis of tool wear evolution. After the operation, actual hole size and geometry were characterized using a coordinate measuring machine, and temperatures and torques were measured during the subsequent implantation phase.

RESULTS

The findings revealed a direct correlation between tool wear and the temperature rise during the drilling phase, while a lower correlation was found with the hole profile geometry variation. The implantation phase demonstrated temperature and torque values within acceptable ranges.

CONCLUSIONS

This study highlights the importance of adhering to proper tool maintenance and replacement protocols. By following recommended guidelines, practitioners can minimize adverse effects and enhance the success of dental implant procedures.

Soft material drilling: A thermo-mechanical analysis of polyurethane foam for biomimetic bone scaffolds and optimization of process parameters using Taguchi method

Drilling is a widely employed technique in machining processes, crucial for efficient material removal. However, when applied to living tissues, its invasiveness must be carefully considered. This study investigates drilling processes on polyurethane foam blocks mimicking human bone mechanical properties. Various drill bit types (118° twist, 135° twist, spherical, and conical), drilling speeds (1000-1600 rpm), and feed rates (20-80 mm/min) were examined to assess temperature elevation during drilling. The Taguchi method facilitated systematic experiment design and optimization. Signal-to-noise (S/N) ratio and analysis of variance (ANOVA) identified significant drilling parameters affecting temperature rise. Validation was conducted through confirmation testing. Results indicate that standard twist drill bits with smaller point angles, lower drilling speeds, and higher feed rates effectively minimize temperature elevation during drilling.

Ultrasonic-assisted drilling of cortical and cancellous bone in a comparative point of view

Background

During bone drilling, a common procedure in clinical surgeries, excessive heat generation and drilling force can cause damage to bone tissue, potentially leading to failure of implants and fixation screws or delayed healing. With this in mind, the aim of this study was to evaluate the efficiency of ultrasonic-assisted drilling compared to conventional drilling as a potential method for bone drilling.

Methods

This study examined optimal drilling parameters based on previous findings and investigated both cortical and cancellous bone. In addition to evaluating drilling force and temperature elevation, the effects of these factors on osteonecrosis and micro-crack formation were explored in ultrasonic-assisted and conventional drilling through histopathological assessment and microscopic imaging. To this end, three drilling speeds and two drilling feed-rates were considered as variables in the in vitro experiments. Furthermore, numerical modeling provided insight into temperature distribution during the drilling process in both methods and compared three different vibration amplitudes.

Results

Although temperature elevations were lower in the conventional drilling, ultrasonic-assisted drilling produced less drilling force. Additionally, the latter method resulted in smaller osteonecrosis regions and did not produce micro-cracks in cortical bone or structural damage in cancellous bone.

Conclusions

Ultrasonic-assisted drilling, which caused less damage to bone tissue in both cortical and cancellous bone, was comparatively more advantageous. Notably, this study demonstrated that to determine the superiority of one method over the other, we cannot rely solely on temperature variation results. Instead, we must consider the cumulative effect of both temperature elevation and drilling force.

Effect of drill quality on biological damage in bone drilling

Bone drilling is a universal procedure in orthopaedics for fracture fixation, installing implants, or reconstructive surgery. Surgical drills are subjected to wear caused by their repeated use, thermal fatigue, irrigation with saline solution, and sterilization process. Wear of the cutting edges of a drill bit (worn drill) is detrimental for bone tissues and can seriously affect its performance. The aim of this study is to move closer to minimally invasive surgical procedures in bones by investigating the effect of wear of surgical drill bits on their performance. The surface quality of the drill was found to influence the bone temperature, the axial force, the torque and the extent of biological damage around the drilling region. Worn drill produced heat above the threshold level related to thermal necrosis at a depth equal to the wall thickness of an adult human bone. Statistical analysis showed that a sharp drill bit, in combination with a medium drilling speed and drilling at shallow depth, was favourable for safe drilling in bone. This study also suggests the further research on establishing a relationship between surface integrity of a surgical drill bit and irreversible damage that it can induce in delicate tissues of bone using different drill sizes as well as drilling parameters and conditions.

Progress in Excision Methods of Bone Materials

Bone resection is a common technique in modern surgery, which can be divided into contact (such as mechanical osteotomy and ultrasonic osteotomy) and non-contact (such as laser osteotomy). Irrespective of the excision method, it causes processing damage to natural bone material, thus affecting bone healing. To reduce the machining damage in bone resection, different machining variables (cutting fluid temperature, feed rate, rotational speed, and ultrasonic frequency) were considered to explore the selection of various cutting conditions. This paper reviews the excision of natural bone materials including mechanical osteotomy, laser osteotomy, and ultrasonic osteotomy, especially traditional drilling and ultrasonic cutting, which represent the traditional and prospective methods of bone excision technology, respectively. Finally, the differences between methods are emphasized and the future trends in osteotomy technology and condition control during osteotomy are analyzed.

Power-Tool Use in Orthopaedic Surgery: Iatrogenic Injury, Its Detection, and Technological Advances: A Systematic Review

Power tools are an integral part of orthopaedic surgery but have the capacity to cause iatrogenic injury. With this systematic review, we aimed to investigate the prevalence of iatrogenic injury due to the use of power tools in orthopaedic surgery and to discuss the current methods that can be used to reduce injury.

3D pull-out finite element simulation of the pedicle screw-trabecular bone interface at strain rates

Biomedical experimental studies such as pull-out (PO), screw loosening experience variability mechanical properties of fresh bone, legal procedures of cadaver bone samples and time-consuming problems. Finite Element Method (FEM) could overcome experimental problems in biomechanics. However, material modelling of bone is quite difficult, which has viscoelastic and viscoplastic properties. The study presents a bone material model which is constructed at the strain rates with the Johnson-Cook (JC) material model, one of the robust constitutive material models. The JC material constants of trabecular bone are determined by the curve fitting method at strain rates for the 3D PO finite element simulation, which defines the screw-bone interface relationship. The PO simulation is performed using the Abaqus/CAE software program. Bone fracture mechanisms are simulated with dynamic/explicit solutions during the PO phenomenon. The paper exposes whether the strain rate has effects on the PO performance. Moreover, simulation reveals the relationship between pedicle screw diameter and PO performance. The results obtained that the maximum pull-out force (POF) improves as both the screw diameter and the strain rate increase. For 5.5 mm diameter pedicle screw POFs were 487, 517 and 1708 N at strain rate 0.00015, 0.015 and 0.015 s^-1, respectively. The FOFs obtained from the simulation of the other screw were 730, 802 and 2008 N at strain rates 0.00015, 0.0015 and 0.015, respectively. PO phenomenon was also simulated realistically in the finite element analysis (FEA).

Integrated analytical hierarchy process and grey relational analysis approach to measure supply chain complexity

Purpose

The purpose of this paper is to understand the drivers that create complexity in the supply chain and develop a mathematical model to measure the level of supply chain complexity (SCC).

Design/methodology/approach

Through extensive literature review, the authors discussed various drivers of SCC. These drivers were classified into five dimensions based on expert opinion. Moreover, a novel hybrid mathematical model was developed by integrating analytical hierarchy process (AHP) and grey relational analysis (GRA) methods to measure the level of SCC. A case study was conducted to demonstrate the applicability of the developed model and analyze the SCC level of the company in the study.

Findings

The authors identified 22 drivers of SCC, which were further clustered into five complexity dimensions. The application of the developed model to the company in the case study showed that the SCC level of the company was 0.44, signifying that there was a considerable scope of improvement in terms of minimizing complexity. The company that serves as the focus of this case study mainly needs improvement in tackling issues concerning government regulation, internal communication and information sharing and company culture.

Originality/value

In this paper, the authors propose a model by integrating AHP and GRA methods that can measure the SCC level based on various complexity drivers. The combination of such methods, considering their ability to convert the inheritance and interdependence of drivers into a single mathematical model, is preferred over other techniques. To the best of the authors' knowledge, this is the first attempt at developing a hybrid multicriteria decision-based model to quantify SCC.

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.

Experimental study on biological damage in bone in vibrational drilling

BACKGROUND

Drilling is a well-known mechanical operation performed for fixing fracture at required locations in bone. The process may produce mechanical and thermal alterations in the structure of the bone and surrounding tissues leading to irreversible damage known as osteonecrosis.

OBJECTIVE

The main purpose of this study was to measure the level of biological damage in bone when a drill assisted by low and high levels of vibrations is penetrated into bone tissue.

METHODS

Histopathology examination of sections of bones has been performed after drilling the bone using a range of vibrational frequency and rotational speed imposed on the drill with and without supply of saline for cooling.

RESULTS

Cell damage in bone was caused by the combined effect of drill speed and frequency of vibrations. Histopathology examination revealed more damage to bone cells when a frequency higher than 20 kHz was used in the absence of cooling. Cooling the drilling region helped minimize cell damage more at a shallow depth of drilling compared to deep drilling in the cortex of cortical bone. The contribution of cooling in minimizing cell damage was higher with a lower drill speed and frequency compared to a higher drill speed and frequency.

CONCLUSION

Vibrational drilling using a lower drill speed and frequency below 25 kHz in the presence of cooling was found to be favorable for safe and efficient drilling in bone.