Effects of repeated sterilization cycles on primary stability of orthodontic mini-screws

Effect of Erbium:YAG Laser Recycling on Mechanical Characteristics of Retrieved Orthodontic Mini-screws

Introduction: This study aimed to evaluate the influence of two recycling methods on the mechanical and surface characteristics of orthodontic mini-screws. Methods: Thirty-six retrieved mini-screws were randomly classified into two equal groups. In the first group (laser recycled group (LG)), the Er:YAG laser (2940 nm, 5.5 W, 275 mJ, perpendicular to the mini-screws at a distance of 7-10 mm, 25 s) was used to recycle mini-screws. In the second group (phosphoric acid and sodium hypochlorite recycled group (ASG)), the mini-screws were kept in 37% phosphoric acid gel (10 minutes) and then placed in 5.25% sodium hypochlorite for 30 minutes. Eighteen new mini-screws were selected as the control group (CG). Maximum insertion torque (MIT), maximum removal torque (MRT), and fracture torque (FT) of all mini-screws were measured. A sample from each group was examined for the surface changes of the mini-screw and tissue remnants under a scanning electron microscope (SEM). Results: The mean MIT was significantly higher in both LG and ASG groups than the CG (P<0.001 and P=0.002, respectively). However, no significant difference was shown between the LG and ASG groups. The mean values of MRT and FT showed no significant difference between the groups. The amount of tissue remnants in the ASG group was significantly higher than that in the LG group. The evidence of porosity and corrosion was observed on the ASG mini-screw surface, and there was an increase in roughness on the LG mini-screw surface. Conclusion: The Er:YAG laser recycling of mini-screws is a proper method causing minimum damage to the screw surface.

Comparison of the primary stability of orthodontic miniscrews after repeated insertion cycles

OBJECTIVES

To compare the primary stability of miniscrews after repeated cycles of insertion through insertion torque (IT) measurements and resonance frequency analysis (RFA).

MATERIALS AND METHODS

Sixty titanium miniscrews were divided into two groups according to the insertion protocol: one with predrilled sites and the other self-drilled into porcine iliac crest bone specimens. Each group had three cycles of reinsertion. After each insertion, the IT and RFA were measured. The IT was measured by using a torque meter, and the RFA was measured using the Osstell ISQ device. A total of five miniscrews of each group were selected for sequential assessment of the morphology of their tip and threads using scanning electron microscopy after each insertion cycle.

RESULTS

No statistically significant differences were found in the IT values of miniscrews reinserted up to three times in the group with predrilled surgical sites. The IT value increased significantly with the number of reinsertions in the self-drilled group. The RFA value decreased as the number of insertions increased in both groups.

CONCLUSIONS

Under the conditions of this in vitro study, reinserting miniscrews deteriorates the integrity of their tip and thread. Reinsertion should be discouraged particularly when insertion sites are not predrilled.

A comparison of risk profile for orthopaedic operations when utilizing individually wrapped screws (IWS) when compared with sterile screw caddies (screw racks)

INTRODUCTION

There has been a global trend towards individually packaged screws for orthopaedic operations. Traditional practice makes use of screw caddies that require re-sterilization. Individually wrapped screws (IWS) are purported to decrease infection rates and avoid the deleterious effects of repeated screw sterilizations, despite marginal evidence. This review aimed to evaluate the safety, effectiveness and economics of screw caddies with IWS.

MATERIAL AND METHODS

The literature was surveyed in a systematic fashion between 1998 and 2017 and all relevant health technology assessments, systematic reviews, meta-analyses, randomized controlled trials, cohort studies, case-controlled studies and case series were sought. Any benefits or otherwise of IWS over screw caddies were then evaluated in the areas of safety, effectiveness and economics.

RESULTS

Two level III-3 papers suggested the use of caddies at least as safe as individual screws. Four level III-2 papers demonstrated that screws from caddies were as effective as individual alternatives, while a level III-3 paper reported that individual screws were significantly more expensive than screw caddies. Cost increases to our regional health service from ankle open reduction and internal fixations alone of at least $50,112 (AUD) per annum were calculated.

CONCLUSIONS

From the results obtained, the authors recommend the continued use of screw caddies for orthopaedic procedures.

Root Resorption of Maxillary Posterior Teeth after Rapid Maxillary Expansion: A Comprehensive Review of the Current Evidence from in-vitro and in-vivo Studies

Background:

The application of heavy forces to the dentition, as those produced during a Rapid Maxillary Expansion (RME), has been associated in the literature with the development of root resorption of maxillary posterior teeth.

Objective:

The aim of the present manuscript was to report the available data from in-vitro and in-vivo studies that can elucidate the biological processes of resorption and repair of radicular cementum after RME.

Methods:

Studies evaluating the occurrence of root resorption after RME by means of histological and radiographic methodology were included. We detailed the changes of the radicular anatomy after RME and provided a synthesis of the most valuable scientific evidence showing the biological processes behind the potential modifications of radicular anatomy. Results. Loss of cementum material and reduction of radicular volumes were seen after rapid maxillary expansion. A small radicular volumetric recovery of anchored teeth occurred after the retention period; this reparative phenomenon was caused by cementum deposition without the reattachment of periodontal fibers, supporting the detrimental effects associated with RR.

Conclusion:

Retention period and the timing of radiographic examination could influence the extension of radicular resorption detected after RME since root resorption and cementum repair may occur at the same time at this stage.

Effect of steam and dry heat sterilization on the insertion and fracture torque of orthodontic miniscrews

BACKGROUND

Titanium miniscrews are used at an ever-increasing rate to provide orthodontic anchorage. The aim of this study was to evaluate the mechanical performance of miniscrews after dry and steam sterilization.

MATERIALS AND METHODS

In this experimental study, a total of 72 miniscrews from two different manufacturers with a diameter of 1.6 mm and height of 8 mm were divided into six groups (n = 12). One group of screws from each manufacturer was considered as the control group; the second underwent steam sterilization; and the last group was subjected to dry sterilization. Insertion and fracture torques of each miniscrew were assessed by a torque tester. Data were analyzed using the Kruskal-Wallis and Mann-Whitney tests (P < 0.05).

RESULTS

For Jeil miniscrew, no statistically significant differences were detected between the steam-sterilized and control groups in their insertion torques (P > 0.05). There was a statistically significant difference between the steam sterilized, dry sterilized and control groups with respect to their fracture torque (P < 0.001). For Hubit miniscrew, there were no significant differences between steam sterilized, dry sterilized and control groups in their insertion torque (P > 0.05) and between steam sterilized and control groups with respect to their fracture torque (P > 0.05). There were significant differences in the mean values of insertion and fracture torques between the two different manufacturers (P < 0.001).

CONCLUSION

Steam sterilization had no detrimental effects on torque values of miniscrews, but dry heat sterilization affected their mechanical properties.

Precautions and recommendations for orthodontic settings during the COVID-19 outbreak: A review

Introduction

Coronavirus disease 2019 (COVID-19) is a contagious disease caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2). It emerged as a global pandemic in early 2020, affecting more than 200 countries and territories. The infection is highly contagious, with disease transmission reported from asymptomatic carriers, including children. It spreads through person-to-person contact via aerosol and droplets. The practice of social distancing—maintaining a distance of 1-2 m or 6 ft—between people has been recommended widely to slow or halt the spread. In orthodontics, this distance is difficult to maintain, which places orthodontists at a high risk of acquiring and transmitting the infection. The objective of this review is to report to orthodontists on the emergence, epidemiology, risks, and precautions during the disease crisis. This review should help increase awareness, reinforce infection control, and prevent cross-transmission within the orthodontic facility.

Methods

A comprehensive literature review of English and non-English articles was performed in March 2020 using COVID-19 Open Research Dataset (CORD-19 2020), PubMed, MEDLINE, Scopus, and Google Scholar to search for infection control and disease transmission in orthodontics.

Results

This review emphasizes minimizing aerosol production and reinforcing strict infection control measures. Compliance with the highest level of personal protection and restriction of treatment to emergency cases is recommended during the outbreak. Surface disinfection, adequate ventilation, and decontamination of instruments and supplies following the guidelines are required.

Conclusions

Reinforcing strict infection control measures and minimizing personal contact and aerosol production are keys to prevent contamination within orthodontic settings. Although no cases of COVID-19 cross-transmission within a dental facility have been reported, the risk exists, and the disease is still emerging. Further studies are required.

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Coronavirus disease 2019 is a highly contagious global pandemic.

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It could transmit by asymptomatic carriers via person-to-person contact, aerosol, and droplets.

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Strict infection control and aerosol containment are required in orthodontic settings.

Steam Sterilization of Equine Bone Block: Morphological and Collagen Analysis

Introduction

The use of equine bone blocks is widely reported for bone augmentation techniques. The block must be shaped according to the form of the defect that should be regenerated. The shaping could be performed by hand before or during the surgery, in a sterile ambient, or using a CNC milling machine that could not be sterile. The aim of our study was to evaluate if a steam sterilization could provide a medical grade sterilization of the blocks and to evaluate if bone microstructure and collagen structures change after different steam sterilization protocols provided by mainstream autoclave.

Materials and Method

Two blocks of equine bone were divided into 16 samples. 1 sample was used as control and not submitted to any treatment. 15 samples were infected with a Streptococcus faecalis bacterial culture. The samples were singularly packed, randomly divided into 3 groups, and submitted to autoclave sterilization on the same device. The groups were submitted to a sterilization cycle (Gr. A: 121°C, 1,16 bar for 20'; Gr. B:134°C, 2,16 bar for 4'; Gr. C: 134°C, 2,16 bar for 3.30 min.). 2 samples for each group were evaluated for the sterility. 3 samples for each group were observed at SEM to notice the macro- and microstructure modification and to confocal microscope to observe the collagen.

Results

All samples were sterile. The SEM evaluation showed, in all groups, a preserved morphological structure. Confocal microscope evaluation shows that the collagen structure appears to be more uniform and preserved in group C.

Conclusion

Data show that autoclave steam sterilization could be reliable to obtain sterilization of equine bone blocks.

Effect of recycling protocol on mechanical strength of used mini-implants

Purpose. This study evaluated the influence of recycling process on the torsional strength of mini-implants. Materials and Methods. Two hundred mini-implants were divided into 4 groups with 50 screws equally distributed in five diameters (1.3 to 1.7 mm): control group (CG): unused mini-implants, G1: mini-implants inserted in pig iliac bone and removed, G2: same protocol of group 1 followed by sonication for cleaning and autoclave sterilization, and G3: same insertion protocol of group 1 followed by sonication for cleaning before and after sandblasting (Al₂O₃-90 µ) and autoclave sterilization. G2 and G3 mini-implants were weighed after recycling process to evaluate weight loss (W). All the screws were broken to determine the fracture torque (FT). The influence of recycling process on FT and W was evaluated by ANOVA, Mann-Whitney, and multiple linear regression analysis. Results. FT was not influenced by recycling protocols even when sandblasting was added. Sandblasting caused weight loss due to abrasive mechanical stripping of screw surface. Screw diameter was the only variable that affected FT. Conclusions. Torsional strengths of screws that underwent the recycling protocols were not changed. Thus, screw diameter choice can be a more critical step to avoid screw fracture than recycling decision.

Systematic review of mini-implant displacement under orthodontic loading

A growing number of studies have reported that mini-implants do not remain in exactly the same position during treatment, although they remain stable. The aim of this review was to collect data regarding primary displacement immediately straight after loading and secondary displacement over time. A systematic review was performed to investigate primary and secondary displacement. The amount and type of displacement were recorded. A total of 27 studies were included. Sixteen in vitro studies or studies using finite element analysis addressed primary displacement, and nine clinical studies and two animal studies addressed secondary displacement. Significant primary displacement was detected (6.4–24.4 µm) for relevant orthodontic forces (0.5–2.5 N). The mean secondary displacement ranged from 0 to 2.7 mm for entire mini-implants. The maximum values for each clinical study ranged from 1.0 to 4.1 mm for the head, 1.0 to 1.5 for the body and 1.0 to 1.92 mm for the tail part. The most frequent type of movement was controlled tipping or bodily movement. Primary displacement did not reach a clinically significant level. However, clinicians can expect relevant secondary displacement in the direction of force. Consequently, decentralized insertion within the inter-radicular space, away from force direction, might be favourable. More evidence is needed to provide quantitative recommendations.

The economic impact of individually packaged screws

BACKGROUND

Trends in orthopaedic surgery have seen a migration towards using individually packaged screws (IPS). The manufacturers claim IPS improves sterility, traceability, and avoids the effects of repeated sterilisation. In recent times there has been increasing pressure on the NHS to be more cost-efficient. Challenging decisions must be made to make cost-efficient choices without comprising the quality of care provided.

AIM

This study investigates the cost-benefit of IPS compared to the conventional screw rack stored screws (SRSS).

METHODS

A single-centred observational study was carried out in a district general hospital between February and March 2013. One-hundred and forty-seven screws were requested intra-operatively and the screw acquisition time was measured with a digital handheld timer. Screw acquisition time was defined as the time taken from the initial verbal request to when the screw was mounted ready for use. The screws were categorised into two groups: SRSS and IPS.

RESULTS

The mean screw acquisition time for the SRSS group (n = 94) was 6.6 s (S.D ± 2.5). The mean screw acquisition time for the IPS group (n = 53) was 102.1 s (S.D ± 25.7). The mean difference between SRSS and IPS was 96 s (95%CI 90.3-100.8; p < 0.001).

CONCLUSION

Our study suggests that the use of IPS significantly (p < 0.001) increases the operation duration and costs compared to SRSS. Based on ankle ORIF procedures alone, the use of IPS could potentially increase department spending by approximately £76,680 per year.