Comparison of primary stability of used and unused self-tapping and self-drilling orthodontic mini-implants.

BACKGROUND: Skeletal anchorage has been the subject of study for many years. Recently, orthodontic mini-implants (MIs) were described as effective tools for anchorage and were named temporary anchorage devices (TADs). The success of MIs depends on their primary stability, which is defined as the lack of mobility in the bone after implant insertion, and the relevant factors affecting primary stability. OBJECTIVES: This study aimed to compare the primary stability of used self-drilling (SD) and self-tapping (ST) MIs with unused ones by performing the insertion torque measurement, Periotest and pull-out test. MATERIAL AND METHODS: Forty-six used (23 ST, 23 SD) and 46 unused (23 ST, 23 SD) MIs (1.5 mm × 8 mm) were inserted into a synthetic bone with the use of a digital screwdriver. Maximum insertion torque (MIT) values were recorded during the placement of MIs, and then Periotest measurements were made. Following the MIT and Periotest measurements, pull-out tests were performed on all MIs. RESULTS: The median MIT values (Ncm) of the MIs were as follows: used ST: 17.3, unused ST: 18.9, used SD: 24.1, unused SD: 25.2. The median values obtained after the Periotest were (±): used ST: 0, unused ST: -1, used SD: -3, unused SD: -3. Median pull-out values (N) were: used ST: 148.12, unused ST: 168.12, used SD: 173.12, unused SD: 203.20. Statistically, MIT and pull-out values of the used ST and SD implants were significantly lower compared to those of the unused ST and SD implants (p < 0.05). CONCLUSIONS: Used orthodontic MIs showed poor performance compared with unused implants when they were inserted again in the in vitro conditions.

Self-drilling screws for the prevention of dental and skeletal injuries during open reduction and internal fixation of pediatric mandibular fractures.

Facial trauma in pediatric population predisposes the child to injury of both the developing skeleton and dentition. This article aims to highlight the experience of the authors through a case report, in using self-drilling screws for fixation of mandibular fractures in pediatric age group. The use of self-drilling screws minimizes the complications such as thermal and/or mechanical damage to the developing dentition and the bone. They also provide significant advantages including ease of availability and technique, superior anchorage with primary stability, and minimizing or avoiding permanent damage to the developing tooth germs in the site of fracture. The use of self-drilling screws for mandibular open reduction and internal fixation in children is an easy, reliable, and safe technique which may have significant value addition in preventing inadvertent injury to the developing tooth germs.

Comparative Evaluation of Drill-Free and Self-Tapping Titanium Miniscrews for Semi-Rigid Internal Fixation in Maxillofacial Trauma.

Introduction: Conventional semi-rigid fixation systems in maxillofacial trauma use self-tapping titanium miniscrews (STS) that require preliminary drilling of a pilot hole. Although drill-free miniscrews (DFS) accompany these systems, they have not dominated practice despite their allure of improved screw-bone contact and holding power. The COVID-19 pandemic has brought these DFS to light as they avoid aerosol production. The present study has compared DFS to STS in patients being treated with miniplate fixation for maxillofacial trauma to understand their feasibility for maxillofacial fracture fixation. Methodology: This prospective case-control study sampled 16 patients each with zygomaticomaxillary buttress fracture and parasymphysis fracture of the mandible and grouped alternating patients as case (DFS) and control (STS). Intraoperatively duration of fixation, incidence of screw failures and fragment stability; postoperatively occlusion, neurosensory deficits, teeth vitality and infection and removal rates were evaluated at postoperative week 1, 3, 6, 12 and 24 using Cramer's V test. A P value < 0.05 was considered significant. Results: In the 32 patients evaluated, DFS reduced internal fixation time at zygomaticomaxillary buttress (P = 0.001) but not at parasymphysis (P = 0.206). No significant difference in screw failures or fragment stability was observed. Stable occlusion was maintained in all groups with vital teeth and intact neurosensory function, but the summative incidence of infection was significant at week 24 when STS was used at parasymphysis (P = 0.019). Discussion: While DFS may facilitate ease of insertion with a single instrument pick-and-screw-in approach, avoiding thermal osteonecrosis and aerosol production, they fail to confer any other clinical advantage.

Self-Drilling Versus Self-Tapping Screws: A 3D Finite Element Analysis.

STUDY DESIGN: Self-tapping and self-drilling screws are two modalities available for plate fixation. When compared to self-drilling, self-tapping screws have a few drawbacks like screw loosening, thermal osteolysis, equipment dependent, and time-consuming. AIM: The aim of this study was to compare the efficacy of self-tapping and self-drilling screws with relation to plate retention and stability in internal fixation of mandibular fractures using 3D finite element analysis (FEA). OBJECTIVES: The objective of this study was to determine the influence of screw placement technique on stress concentration and deformation occurring at the screw-bone interface in self-drilling and self-tapping screws. MATERIALS AND METHODS: A 3D computer-aided design modeling system was used to build a trilaminate mandibular bone, self-tapping screw and self-drilling screw, and a 2-holed miniplate with gap that were converted into finite element models using Hypermesh 13.0 software. Material properties and boundary conditions were assigned to these models. Pullout, torque, and torsional forces were applied to evaluate the stress concentration and deformation at the screw-bone interface. RESULTS: The comparison of stress concentration and deformation values between the two types of screws was interpreted using ANSYS software version 14.5. Results of torque test, pullout test, and torsional test showed maximum Von Mises stress, and deformation around the screw-bone interface was higher in self-tapping screw than in self-drilling screw. CONCLUSION: Within the limitations of the 3D FEA, the findings provided significant evidence to suggest that self-tapping screws have a greater incidence of fatigue when compared to self-drilling screws as there was more stress distribution and deformation at their screw-bone interface.

Cannulated Self-Drilling, Self-Tapping Pins for Displaced Extra-articular Distal Radius Fractures.

Displaced unstable extra-articular radius fractures are common and frequently treated with open reduction and internal fixation with a fixed-angle volar plate. Although this treatment yields good results, it might be more invasive than necessary for management of this often relatively simple fracture. In this article, we present the technique of using a cannulated self-drilling, self-tapping (CSDT) construct that can be employed in a minimally invasive fashion. The CSDT offers a minimally invasive alternative to volar fixed-angle plating for unstable extra-articular distal radius fractures. It also can be useful in isolated displaced radial styloid fractures. Placed appropriately, implants rarely have to be removed. The CSDT also allows for early motion and rapid return to activities with anticipated satisfactory range of motion and function.

Self-drilling and self-tapping miniscrews for osteosynthesis fixture after LeFort I osteotomy: An ex vivo trial for primary stability and a randomized clinical study.

BACKGROUND: Self-drilling osteosynthesis screws (SDS) have a potential higher primary stability together with clinical advantages such as less time effort compared to self-tapping screws (STS). The aims of the study were to compare the primary stability of SDS and STS ex vivo and to analyze of the time-saving effect in vivo. MATERIALS AND METHODS: Ex vivo, both screws were placed in porcine bone. Torque was measured for insertion and removal. Four specimens were kept in bone for histologic bone-to-implant-contact examination. In vivo, 49 patients who received orthognathic surgery in the maxilla were included in 2 centers. In a split-mouth design, the time for osteosynthesis fixation and perioperative events were recorded. RESULTS: Ex vivo, insertion and removal torque measurements were higher for SDS, especially in dense bone. Histologic imaging on the exemplary-stained specimens showed higher bone contact and compressed bone matrix for SDS in all bone densities. In vivo, the mean osteosynthesis time in both centers was 5.5 min (±3.03) for SDS and 5.5 min (±2.37) for STS. Separate analysis showed that center I was faster with STS and center II with SDS. Although, in center I a higher rate of failed primary stability of SDS compared to STS was documented. CONCLUSIONS: SDS showed a partially higher primary stability ex vivo, especially in dense bone. The timesaving effect of SDS is less pronounced than expected, but technically SDS might be favorable where drilling is difficult or even impossible.

A Precise Method of Measuring Simultaneous Intrusion and Uprighting of Mandibular Molar Using Denta Scan - A Case Report.

A commonly encountered problem in prosthetic dentistry is the supra eruption of teeth due to absence of opposing teeth. Consequently, replacement of the missing teeth with prosthesis becomes difficult due to lack of vertical dimension of the edentulous area. This article describes the space regaining procedure in a 14-year-old female patient who wanted a fixed prosthesis for her missing maxillary 1st molar. On examination, it was observed that mandibular 1st molar had supraerupted and tipped lingually. After considering the various treatment modalities it was decided to simultaneously intrude and upright the mandibular molar using a mini-implant. The precise measurements of intrusion and uprighting were done using Dentascan software. Intrusion of 1.8mm and buccolingual uprighting of 2.3mm was achieved in 45 days. The mini-implant is an efficient non-compliance device to intrude and upright the tooth simultaneously. Dentascan is an accurate and very precise method of measuring the intrusion and uprighting of teeth.

Effect of surface anodization on stability of orthodontic microimplant.

OBJECTIVE: To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. METHODS: A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. RESULTS: There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 ± 1.39 Ncm) than for the machined ones (2.05 ± 1.07 Ncm) (p < 0.01). The interfacial strengths, converted from PRT, were calculated at 10.6 MPa and 5.74 MPa for the anodized and machined group implants, respectively. CONCLUSIONS: Anodization of orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage.

Effect of surface anodization on stability of orthodontic microimplant / 대한치과교정학회지

OBJECTIVE: To determine the effect of surface anodization on the interfacial strength between an orthodontic microimplant (MI) and the rabbit tibial bone, particularly in the initial phase after placement. METHODS: A total of 36 MIs were driven into the tibias of 3 mature rabbits by using the self-drilling method and then removed after 6 weeks. Half the MIs were as-machined (n = 18; machined group), while the remaining had anodized surfaces (n = 18; anodized group). The peak insertion torque (PIT) and the peak removal torque (PRT) values were measured for the 2 groups of MIs. These values were then used to calculate the interfacial shear strength between the MI and cortical bone. RESULTS: There were no statistical differences in terms of PIT between the 2 groups. However, mean PRT was significantly greater for the anodized implants (3.79 +/- 1.39 Ncm) than for the machined ones (2.05 +/- 1.07 Ncm) (p < 0.01). The interfacial strengths, converted from PRT, were calculated at 10.6 MPa and 5.74 MPa for the anodized and machined group implants, respectively. CONCLUSIONS: Anodization of orthodontic MIs may enhance their early-phase retention capability, thereby ensuring a more reliable source of absolute anchorage.

Influence of surface treatment on the insertion pattern of self-drilling orthodontic mini-implants / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare self-drilling orthodontic mini-implants of different surfaces, namely, machined (untreated), etched (acid-etched), RBM (treated with resorbable blasting media) and hybrid (RBM + machined), with respect to the following criteria: physical appearance of the surface, measurement of surface roughness, and insertion pattern. METHODS: Self-drilling orthodontic mini-implants (Osstem implant, Seoul, Korea) with the abovementioned surfaces were obtained. Surface roughness was measured by using a scanning electron microscope and surface-roughness-testing machine, and torque patterns and vertical loadings were measured during continuous insertion of mini-implants into artificial bone (polyurethane foam) by using a torque tester of the driving-motor type (speed, 12 rpm). RESULTS: The mini-implants with the RBM, hybrid, and acid-etched surfaces had slightly increased maximum insertion torque at the final stage (p < 0.05). Implants with the RBM surface had the highest vertical load for insertion (p < 0.05). Testing for surface roughness revealed that the implants with the RBM and hybrid surfaces had higher Ra values than the others (p < 0.05). Scanning electron microscopy showed that the implants with the RBM surface had the roughest surface. CONCLUSIONS: Surface-treated, self-drilling orthodontic mini-implants may be clinically acceptable, if controlled appropriately.

Finite element analysis of cortical bone strain induced by self-drilling placement of orthodontic microimplant / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the strain induced in the cortical bone surrounding an orthodontic microimplant during insertion in a self-drilling manner. METHODS: A 3D finite element method was used to simulate the insertion of a microimplant (AbsoAnchor SH1312-7, Dentos Co., Daegu, Korea) into 1 mm thick cortical bone. The shape and dimension of thread groove in the center of the cortical bone produced by the cutting flute at the apical of the microimplant was obtained from animal test using rabbit tibias. A total of 3,600 analysis steps was used to calculate the 10 turns and 5 mm advancement of the microimplant. A series of remesh in the cortical bone was allowed to accommodate the change in the geometry accompanied by the implant insertion. RESULTS: Bone strains of well higher than 4,000 microstrain, the reported upper limit for normal bone remodeling, were observed in the peri-implant bone along the whole length of the microimplant. Level of strains in the vicinity of either the screw tip or the valley part were similar. CONCLUSIONS: Bone strains from a microimplant insertion in a self-drilling manner might have a negative impact on the physiological remodeling of cortical bone.