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Bioengineering (Basel, Switzerland) Apr 2024The efficacy of retainers is a pivotal concern in orthodontic care. This study examined the biomechanical behaviour of retainers, particularly the influence of retainer...
The efficacy of retainers is a pivotal concern in orthodontic care. This study examined the biomechanical behaviour of retainers, particularly the influence of retainer stiffness and tooth resilience on force transmission and stress distribution. To do this, a finite element model was created of the lower jaw from the left to the right canine with a retainer attached on the oral side. Three levels of tooth resilience and variable retainer bending stiffness (influenced by retainer type, retainer diameter, and retainer material) were simulated. Applying axial or oblique (45° tilt) loads on a central incisor, the force transmission increased from 2% to 65% with increasing tooth resilience and retainer stiffness. Additionally, a smaller retainer diameter reduced the uniformity of the stress distribution in the bonding interfaces, causing concentrated stress peaks within a small field of the bonding area. An increase in retainer stiffness and in tooth resilience as well as a more oblique load direction all lead to higher overall stress in the adhesive bonding area associated with a higher risk of retainer bonding failure. Therefore, it might be recommended to avoid the use of retainers that are excessively stiff, especially in cases with high tooth resilience.
PubMed: 38671815
DOI: 10.3390/bioengineering11040394 -
Medicine Apr 2024This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and...
This paper demonstrates a digital manufacturing technique of a removable orthodontic appliance from an intraoral scan. An intraoral scan was made for the maxillary and mandibular arches. 3Shape Orthodontics Appliance Designer produced the virtual Hawley retainer, consisting of alloy components (Adam Clasps and Fitted Labial bow) and a base plate. The base plate design was modified to adapt to inserting the alloy components, which were combined using cold-cured acrylic. The finished Hawley retainer was assessed intraorally. The described technique emphasizes the design specifications of digitally designed and manufactured removable orthodontic appliances. A combination of additive and subtractive techniques was successfully employed to manufacture the alloy components and base plate. This novel method provides an alternative approach to manufacturing removable appliances with computer-aided design (CAD)/computer-aided manufacturing (CAM) technologies. The described process offers a precursor to digital manufacturing of other developed designs of dental appliances.
Topics: Humans; Printing, Three-Dimensional; Computer-Aided Design; Orthodontic Appliance Design; Polymers; Benzophenones; Polyethylene Terephthalates; Ketones; Alloys; Orthodontic Appliances, Removable
PubMed: 38669369
DOI: 10.1097/MD.0000000000038004 -
Cureus Apr 2024Orthodontists have a variety of options available for retainers. Research in Orthodontics focuses on assessing outcomes important to clinicians; however, there is... (Review)
Review
Orthodontists have a variety of options available for retainers. Research in Orthodontics focuses on assessing outcomes important to clinicians; however, there is inconsistency in how these outcomes are selected and evaluated. This review sought to assess the effects of different orthodontic retainers on patients' quality of life (QoL). Various approaches were employed in this systematic review, and a thorough search was conducted across six databases. The review involved a comprehensive evaluation of six included studies, highlighting changes in dental structure post-treatment, emphasizing the role of extraction procedures and the quality of debonding in improving retention. The study identified key outcomes for orthodontic clinical trials, highlighting orthodontists' preferences for specific retainer types. Moreover, it discussed the impact of sociocultural influences on retention care. Involving patients actively in discussions about whether to end or extend the retention phase was deemed essential. Noteworthy improvements in occlusal outcomes were linked to extraction treatments. Gender and malocclusion severity influenced QoL before and after orthodontic treatment. The degree of improvement observed in the Class III malocclusion group was comparatively lower than that in the Class I and Class II groups. Orthodontic treatment was found to yield favorable psychological outcomes, as evidenced by notable enhancements in self-esteem and social engagement among individuals. Fixed appliances were shown to negatively affect oral health-related quality of life (OHRQoL), particularly for those with aesthetic and functional concerns. A consensus has been reached on the essential themes and outcomes that should be incorporated in clinical trials related to orthodontic retention for non-cleft and non-surgical cases.
PubMed: 38659711
DOI: 10.7759/cureus.58843 -
The Angle Orthodontist May 2024To investigate the dimensional stability of various 3D-printed models derived from resin and plant-based, biodegradable plastics (PLA) under specific storage conditions...
OBJECTIVES
To investigate the dimensional stability of various 3D-printed models derived from resin and plant-based, biodegradable plastics (PLA) under specific storage conditions for a period of up to 21 weeks.
MATERIALS AND METHODS
Four different printing materials, including Draft V2, study model 2, and Ortho model OD01 resins as well as PLA mineral, were evaluated over a 21-week period. Eighty 3D-printed models were divided equally into two groups, with one group stored in darkness and the other exposed to daylight. All models were stored at a constant room temperature (20°C). Measurements were taken at 7-week intervals using the Inspect 3D module in OnyxCeph software (Image Instruments GmbH, Chemnitz, Germany).
RESULTS
Dimensional change was noted for all of the models with shrinkage of up to 0.26 mm over the study period. Most contraction occured from baseline to T1, although significant further contraction also arose from T1 to T2 (P < .001) and T1 to T3 (P < .001). More shrinkage was observed when exposed to daylight overall and for each resin type (P < .01). The least shrinkage was noted with Ortho model OD01 resin (0.16 mm, SD = 0.06), and the highest level of shrinkage was observed for Draft V2 resin (0.23 mm, SD = 0.06; P < .001).
CONCLUSIONS
Shrinkage of 3D-printed models is pervasive, arising regardless of the material used (PLA or resin) and being independent of the brand or storage conditions. Consequently, immediate utilization of 3D printing for orthodontic appliance purposes may be preferable, with prolonged storage risking the manufacture of inaccurate orthodontic retainers and appliances.
Topics: Printing, Three-Dimensional; Orthodontic Retainers; Software; Polyesters; Materials Testing
PubMed: 38639456
DOI: 10.2319/081223-557.1 -
American Journal of Orthodontics and... Jul 2024In digital dentistry, virtual attachment removal (VAR) optimizes clear aligner therapy by enhancing efficiency for refinements and enabling prefabricated retainer...
INTRODUCTION
In digital dentistry, virtual attachment removal (VAR) optimizes clear aligner therapy by enhancing efficiency for refinements and enabling prefabricated retainer production through the removal of attachments from a digital scan before the clinical removal of clear aligner attachments. This prospective clinical study aimed to evaluate the accuracy of VAR in the maxillary arch.
METHODS
A total of 110 teeth were analyzed from a sample of 54 maxillary scans from 25 subjects. Models with attachments were virtually debonded using Meshmixer (Autodesk, San Rafael, Calif) and superimposed over the control group in MeshLab. Vector Analysis Module (Canfield Scientific, Fairfield, NJ) was used to calculate and analyze 3-dimensional Euclidean distances on the buccal surfaces between the superimposed models. Statistical analysis was performed using SPSS (version 23.0, IBM, Armonk, NY). The Shapiro-Wilkes (α = 0.05) test determined a nonnormal distribution of results. The Kruskal-Wallis (α = 0.05) was used to determine differences between different tooth types and the number of attachments.
RESULTS
The VAR protocol showed no statistical differences in the root mean square between different tooth segments with an overall tendency for inadequate attachment removal. No difference between the groups was found regarding the number of attachments when used as a main factor.
CONCLUSIONS
The VAR technique is precise enough for the fabrication of retainers from printed dental models in a clinical setting and is not affected by the number of attachments on the tooth.
Topics: Humans; Prospective Studies; Imaging, Three-Dimensional; Female; Male; Maxilla; Young Adult; Orthodontic Appliance Design; Tooth Movement Techniques; Adult; Adolescent; Orthodontic Retainers; Models, Dental; Computer-Aided Design
PubMed: 38597867
DOI: 10.1016/j.ajodo.2024.02.006 -
Journal of Pharmacy & Bioallied Sciences Feb 2024This study aimed to evaluate and compare the bond strengths of four different lingual retainers and assess the adhesive remnant index (ARI) to determine their...
OBJECTIVE
This study aimed to evaluate and compare the bond strengths of four different lingual retainers and assess the adhesive remnant index (ARI) to determine their effectiveness in orthodontic retention.
METHODOLOGY
Eighty human incisor teeth were divided into four groups, with each group bonded using a different retainer: Group 1 (E-Glass retainer), Group 2 (0.017" Co-axial stainless steel wire), Group 3 (Splint C.T. fiber mesh), and Group 4 (0.010" stainless steel ligature wire). Bond strength was measured using a universal testing machine, and ARI scores were recorded to assess bond failure types.
RESULTS
Group 1 (E-Glass retainer) demonstrated the highest bond strength, followed by Group 3 (Splint C.T. fiber mesh), Group 2 (Co-axial stainless steel wire), and Group 4 (stainless steel ligature wire). Cohesive bond failures were observed in most groups, except for the co-axial stainless steel wire group, which exhibited adhesive failures.
CONCLUSION
E-Glass fiber-reinforced retainers showed the highest bond strength, making them a promising alternative to conventional stainless steel wires for orthodontic retention, especially in patients with esthetic concerns or nickel hypersensitivity. Stainless steel retainer groups exhibited lower bond strengths, and cohesive bond failures were prevalent. Further research is needed to validate these findings in clinical settings and evaluate the long-term effectiveness of different lingual retainers.
PubMed: 38595395
DOI: 10.4103/jpbs.jpbs_491_23 -
Journal of Pharmacy & Bioallied Sciences Feb 2024After undergoing comprehensive orthodontic treatment, maintaining the achieved results and preventing relapse remains a significant concern. Various retention protocols...
BACKGROUND
After undergoing comprehensive orthodontic treatment, maintaining the achieved results and preventing relapse remains a significant concern. Various retention protocols have been proposed to address this issue, but their comparative effectiveness is not well-established.
MATERIALS AND METHODS
This study aimed to evaluate the effectiveness of different retention protocols in preventing posttreatment relapse following comprehensive orthodontic treatment. A sample of 150 orthodontic patients who had completed their treatment was included in the study. The patients were divided into three groups based on the retention protocol they received: Group A (Hawley retainers), Group B (Essix retainers), and Group C (permanent retainers). Patients' dental casts were obtained at the end of the treatment (T0) and six months after treatment (T1). Various measurements, including anterior and posterior occlusal changes, were recorded.
RESULTS
The results revealed that Group C (permanent retainers) showed the least amount of relapse compared to Groups A and B. In Group C, the mean anterior relapse was 0.2 mm, while in Groups A and B, it was 1.0 mm and 0.8 mm, respectively. Similarly, the mean posterior relapse in Group C was 0.1 mm, whereas in Groups A and B, it was 0.8 mm and 0.6 mm, respectively. These findings indicate that permanent retainers were more effective in preventing relapse compared to removable retainers.
CONCLUSION
In preventing posttreatment relapse after comprehensive orthodontic treatment, permanent retainers demonstrated superior effectiveness compared to Hawley and Essix retainers.
PubMed: 38595388
DOI: 10.4103/jpbs.jpbs_833_23 -
Turkish Journal of Orthodontics Mar 2024To investigate the most common retention practices, factors influencing the retention protocol, and the differences among orthodontists regarding retention practices.
OBJECTIVE
To investigate the most common retention practices, factors influencing the retention protocol, and the differences among orthodontists regarding retention practices.
METHODS
An online validated questionnaire was anonymously sent to 3,000 orthodontic residents and clinicians. The survey consisted of 19 questions regarding the participants' demographics, prescribed retention appliances, factors affecting retention appliance choices, and adjunctive retention procedures. Descriptive statistics, Chi2 and Kendall's Tau-b tests were applied.
RESULTS
Five hundred fifty-five orthodontic residents and clinicians, 53.3% males and 46.7% females, completed the survey, indicating a response rate of 18.5%. Although participants' demographics, type of treatment and pre-treatment malocclusion influence the choice of retention protocols, thermoplastic retainers (TR) were the most popular retention regime for the maxillary arch for both adults (47.4%) and adolescents (42.3%). Bonded retainers (BR) were the favored option for the mandibular arch (44.9% of adults and 40.7% of adolescents). The degree of arch expansion (64.1%) and the degree of interdigitation (50.1%) after treatment were the most influential factors for the choice of the preferred type of retainers by the respondents. 68.6% of the participants thought professional retention guidelines would be useful.
CONCLUSION
Thermoplastic retainers were the most common retention appliances for adults and adolescents in the maxilla. At the same time, BR was the most favored retainer in the mandibular arch, with clinical experience, practice setting, and malocclusion- and treatment-related factors influencing the type of the chosen appliance. The demographic differences and the uneven participation in the survey need to be considered while interpreting the findings of this study.
PubMed: 38556949
DOI: 10.4274/TurkJOrthod.2023.2022.179 -
Cureus Feb 2024Background With the advent of 3D printing, many more possibilities have arisen for treatment planning. 3D rapid prototyping has enabled us to see a whole other dimension...
Background With the advent of 3D printing, many more possibilities have arisen for treatment planning. 3D rapid prototyping has enabled us to see a whole other dimension that has helped us to give the best possible care for our patients. With more and more advancements being made in this subject, it becomes necessary to check the reliability of the equipment and its effectiveness in the management of the problem at hand. This original study was conducted with the aim of checking the accuracy, dimensional stability, and reliability of orthodontic retainers made on a conventional and digitally fabricated model over a six-month period after debonding. Material and methods The patients were selected from those who have completed fixed orthodontic mechanotherapy from the Department of Orthodontics and Dentofacial Orthopaedics, Sri Guru Ram Das Institute of Dental Sciences and Research, Sri Amritsar. Fifty patients received a clear retainer, which was fabricated for the upper and lower arch after removing the brackets. Patients were included in this study irrespective of their age groups. The manual method used a vacuum-forming machine to fabricate six retainers on stone models. In the digital method, new impressions were taken after three months, and digital models were obtained through 3D scanning and printing, followed by clear retainer fabrication. The data were gathered through a systematic process involving manual and digital methods for clear retainer fabrication and subsequent evaluation. The data obtained was computed for statistical evaluation and comparison. Results Mean and standard deviations of conventional (manual) and digital variables in the two groups were calculated. An ANOVA test was used to evaluate statistically significant differences for mesiodistal width and buccolingual width, and a post hoc Tuckey test was applied for multiple comparisons. The results indicated that most mesiodistal and buccolingual width measurements showed non-significant variations and exhibited a good correlation. Extraction space opening, assessed through an independent t-test for both the maxilla and mandible, also yielded non-significant and comparable results. Additionally, intra-operator and inter-operator measurements using a digital caliper demonstrated high agreement. Intra-class correlation (ICC) values exceeded 0.75, and inter-operator ICC results reflected a high level of agreement ranging from 0.8 to 0.99. Conclusion The primary objective of this study was to establish a correlation between the accuracy, dependability, and clinical efficacy of orthodontic retainers produced using both conventional and digitally created models. This investigation spanned a duration of six months following the removal of orthodontic brackets. The results showed that most of the statistically significant values were due to the inherent potential of the 3D printer for polymerization shrinkage, which, being a stereolithographic 3D printer, had a potential for a slight dimensional shift in the transverse dimension. However, the mean difference between all the models printed was slight and clinically insignificant.
PubMed: 38523938
DOI: 10.7759/cureus.54740 -
Periodontology 2000 Mar 2024Post-treatment change in the form of true relapse and physiological and maturational effects is common following orthodontics. The unpredictable nature of these... (Review)
Review
Post-treatment change in the form of true relapse and physiological and maturational effects is common following orthodontics. The unpredictable nature of these manifestations dictates a conservative, near-universal approach to retention. Both fixed and removable forms of retention are popular with the latter constrained by variable levels of adherence particularly in the medium- to long-term. Fixed retention may offer a more predictable means of preservation of orthodontic outcomes; however, this advantage is offset by the requirement for prolonged supervision and the potential for adverse changes including periodontal breakdown. Nevertheless, while examples of severe complications are common, a clear causal relationship between intact, passive retainers and periodontal issues does not appear to exist. Nevertheless, the importance of diligent maintenance and careful supervision during fixed retention, in particular, cannot be disregarded.
PubMed: 38497610
DOI: 10.1111/prd.12560