IPR treatment and attachments design in clear aligner therapy and risk of open gingival embrasures in adults

Risk factors for open gingival embrasures after clear aligners treatment: a retrospective study

BACKGROUND

To explore the incidence and risk factors of open gingival embrasures (OGEs) in the front region of adult none-extraction cases with clear aligner treatment (CAT).

METHODS

This retrospective study included eighty-two adult patients with non-extraction and CAT treatment, all of which were provided by Invisalign. A total of 820 tooth sites were assessed for OGEs in intraoral photographs. These sites were categorized into nonoccurrence group and occurrence group. The parameters- including crown shape, root angulation (parallel root recorded as zero and divergent root as positive), distance between cementoenamel junction, and distance from interproximal contact point (ICP) to alveolar bone crest (ABC)- were compared between occurrence group and nonoccurrence group using independent t-test and were further analyzed based on the severity. Logistic regression analysis was used to determine the significant risk factors of OGEs.

RESULTS

The overall incidence of OGEs was 13.4% in the maxilla and 30.7% in the mandible. The highest incidence was found between the mandibular central incisors, reaching 39.02%. Age (Maxilla: OR = 1.119, 95%CI (1.048-1.195); Mandible: OR = 1.068, 95%CI (1.018-1.121), mandibular crowding (OR = 0.846, 95%CI (0.729-0.981), distance between adjacent maxillary teeth at the cementoenamel junction (Maxilla: OR = 2.400, 95%CI (1.146-5.027) and distance from ICP to ABC (Maxilla: OR = 8.046, 95%CI (4.016-16.122); Mandible: OR = 3.475, 95%CI (2.390-5.052) in the maxilla and mandible have significant correlation with the occurrence of OGEs (P<0.05).

CONCLUSIONS

OGE is a common complication after CAT, adversely affecting the smiling aesthetics. Clinicians should be well aware of risk factors, such as age, degree of dental crowding, and the distance from the ICP to ABC.

Predictability of incisal labiolingual inclination, overjet, and overbite changes, and the prevalence of open gingival embrasures in patients with mandibular incisor extraction treated with Invisalign: A retrospective cohort study

INTRODUCTION

This retrospective study aimed to assess differences between the planned Invisalign (Align Technology, San Jose, Calif) ClinCheck tooth movements and the achieved outcomes for patients with single mandibular incisor extraction with respect to overjet, overbite, and labiolingual inclination for the initial series of aligners and to assess the prevalence of open gingival embrasures (OGEs) in the former extraction sites.

METHODS

The records of 83 patients who received Invisalign treatment with extraction of a single mandibular incisor were evaluated. The predicted and achieved overjet and overbite measurements were compared using the Invisalign ClinCheck software. The prevalence of an OGE was assessed visually using posttreatment digital models. The labiolingual inclination of the mandibular incisors was measured through superimposition of the pretreatment, predicted posttreatment, and achieved posttreatment digital models using Geomagic Control X (version 2018 1.0; 3D Systems, Rock Hill, SC) metrology software.

RESULTS

Differences between predicted and achieved labiolingual inclination changes of the mandibular incisors were minor in the lingual direction (90.4%); however, planned labial movements were significantly underexpressed (59.0%). A comparison of the predicted and achieved overjet values revealed a clinical expression of 49.6% and 76.0% when the overjet was planned to decrease and increase, respectively. With respect to the predicted and achieved overbite changes, no significant difference was found when the overbite was predicted to increase. In contrast, when the overbite was predicted to decrease, only 50.5% of this planned overbite reduction was clinically achieved. Most patients (95.2%) displayed an OGE in the former extraction space.

CONCLUSIONS

Extraction of a single mandibular incisor in conjunction with Invisalign treatment resulted in an underexpression of the predicted proclination of the mandibular incisors, overjet changes, and overbite reduction. The development of an OGE was highly probable after the initial CAT aligner series.

Impact of clear aligners on gingivitis incidence and prevention strategies in adolescents and adults: a prospective observational study

OBJECTIVE

This study aims to analyze the differences in gingivitis incidence among adolescents and adults using clear aligners for orthodontic correction and to evaluate the effectiveness of prevention strategies on orthodontic outcomes.

METHODS

This observational study included 120 patients undergoing clear aligner orthodontic treatment from June 2018 to September 2023. Participants were divided into an adolescent group (66 cases) and an adult group (54 cases), each further split into a study group and a control group. The control group patients maintained their daily lifestyle throughout the study period. The study group received personalized oral hygiene education and guidance on self-oral care techniques at each follow-up visit. Routine periodontal treatment and personalized oral hygiene education were provided, and the incidence of gingivitis was evaluated six months post-treatment. Statistical methods, including chi-square tests for categorical data, t-tests for continuous variables, and two-way ANOVA for group comparisons, were employed to ensure the robustness of the results.

RESULTS

The incidence of gingivitis was significantly higher in the adolescent group compared to the adult group (P < 0.05). Specifically, within the adolescent group, the study group exhibited a higher gingival index (GI) than the control group (P < 0.05), while the difference in the adult group was not significant.

CONCLUSION

During clear aligner orthodontic treatment, adolescents are more prone to developing gingivitis than adults. Additionally, basic periodontal therapy, as opposed to verbal oral health education alone, can moderately reduce the incidence of gingivitis in clear aligner patients during treatment.

Viscoelastic and antimicrobial dental care bioplastic with recyclable life cycle

Medical plastic-appliance-based healthcare services, especially in dentistry, generate tremendous amounts of plastic waste. Given the physiological features of our mouth, it is desirable to substitute dental care plastics with viscoelastic and antimicrobial bioplastics. Herein, we develop a medical-grade and sustainable bioplastic that is viscoelastic enough to align the tooth positions, resists microbial contamination, and exhibits recyclable life cycles. In particular, we devise a molecular template involving entanglement-inducing and antimicrobial groups and prepare a silk fibroin-based dental care bioplastic. The generated compactly entangled structure endows great flexibility, toughness, and viscoelasticity. Therefore, a satisfactory orthodontic outcome is accomplished, as demonstrated by the progressive alignment of male rabbit incisors within the 2.5 mm range. Moreover, the prepared bioplastic exhibits resistance to pathogenic colonization of intraoral microbes such as Streptococcaceae and Veillonellaceae. Because the disentanglement of entangled domains enables selective separation and extraction of the components, the bioplastic can be recycled into a mechanically identical one. The proposed medical-grade and sustainable bioplastic could potentially contribute to a green healthcare future.

Effect of interproximal enamel reduction on interradicular bone volume in clear aligner therapy: a three-dimensional cone-beam computed tomography study

OBJECTIVES

To assess the effect of inter-proximal enamel reduction (IPR) on interradicular bone volume and incisal inclination in patients undergoing clear aligner therapy (CAT).

MATERIALS AND METHODS

The study sample consisted of 60 cases which underwent orthodontic CAT, in a private clinic in Dammam, KSA. A total of 120 CBCT scans (60 pre-treatment and 60 post- treatment) were measured using the CS 3D Imaging software to examine bone volume (using height, width, and depth of the interproximal area) and incisal inclination. The corresponding ClinCheck models were collected to determine the amount and locations of interproximal reduction performed. Little's Irregularity Index values were measured using OrthoCAD software. Paired sample t-test was used to address the measurements of bone height, width, depth, bone volume, and inclination of upper and lower incisors before and after IPR.

RESULTS

IPR did not affect the upper or lower bone volume except at LR3-2 and UL 2 - 1 where a significant difference between the bone volume with and without IPR was detected (p = 0.02 and p = 0.04 respectively). Upper and lower incisor inclination showed a statistically significant decrease after IPR. There was no correlation between IPR and bone volume difference between upper and lower teeth except at LR3-2 and UL 2 - 1.

CONCLUSIONS

IPR had no significant effect on inter-radicular bone volume except at areas of lower right canine-lateral and at areas of upper left central-lateral. There was a positive correlation between the amount of IPR and incisal inclination.

CLINICAL RELEVANCE

The current study findings suggest that while IPR has a minimal and localized effect on bone volume in certain areas, it plays a role in adjusting incisal inclination, highlighting its significance in the careful planning of orthodontic treatment using clear aligners.

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

Interproximal reduction (IPR) has become a standard practice in orthodontic treatment, particularly in the clear aligner therapy. It became an integral part of the digital plan when using clear aligners. Given the irreversible nature of IPR, precise planning and performance is essential. This article aims to analyze and summarize the existing literature on IPR in the context of clear aligners. The goal is to help clinicians to gain essential knowledge for safely and effectively navigating IPR. The review critically examines different perspectives found in the literature, covering indications, methods, and outcomes. Topics exploring the impact of IPR on treatment outcomes include space gaining, addressing tooth size discrepancies, tooth shape adjustments, resolving malocclusion, and enhancing aesthetics. Emphasizing precision of the procedure by the clinician and awareness of contraindications, the article also discusses the impact of IPR on patients. This includes considerations like increased pulp temperature, susceptibility to cavities due to changes in enamel roughness, effects on soft tissues, and post-IPR tooth sensitivity.

Digital orthodontic setup and clear aligners system for treating adult patients with periodontitis: a descriptive case report

This case report describes the treatment of an adult female patient with a history of periodontitis (Stage 3 -Grade B) and presenting significant crowding in both maxillary and mandibular arches. After periodontal stabilization, the patient underwent orthodontic treatment with clear aligners (CAT) for less than one year. CAT provided an effective quantitative and qualitative control of the forces applied to resolve the malocclusion. This case report provides a detailed description of the clinical strategy and features associated with the clear aligners system which were considered ideal tools for treating periodontal patients during the decisional workflow. The orthodontic treatment goals have been successfully achieved considering functional, periodontal, and aesthetic expectations. Several characteristics of clear aligners could support the recurrence of this orthodontic system for treating patients with a history of periodontitis or at risk of periodontal damage.

Effective contribution ratio of the molar during sequential distalization using clear aligners and micro-implant anchorage: a finite element study

INTRODUCTION

This study aims to investigate the biomechanical effects of anchorage reinforcement using clear aligners (CAs) with microimplants during molar distalization. And also explores potential clinical strategies for enhancing anchorage in the sequential distalization process.

METHODS

Finite element models were established to simulate the CAs, microimplants, upper dentition, periodontal ligament (PDL), and alveolar bone. In group set I, the 2nd molars underwent a distal movement of 0.25 mm in group set II, the 1st molars were distalized by 0.25 mm after the 2nd molars had been placed to a target position. Each group set consisted of three models: Model A served as the control model, Model B simulated the use of microimplants attached to the aligner through precision cuts, and Model C simulated the use of microimplants attached by buttons. Models B and C were subjected to a series of traction forces. We analyzed the effective contribution ratios of molar distalization, PDL hydrostatic stress, and von Mises stress of alveolar bone.

RESULTS

The distalization of the 2nd molars accounted for a mere 52.86% of the 0.25-mm step distance without any reinforcement of anchorage. The remaining percentage was attributed to the mesial movement of anchorage teeth and other undesired movements. Models B and C exhibited an increased effective contribution ratio of molar distalization and a decreased loss of anchorage. However, there was a slight increase in the undesired movement of molar tipping and rotation. In group set II, the 2nd molar displayed a phenomenon of mesial relapse due to the reciprocal force produced by the 1st molar distalization. Moreover, the efficacy of molar distalization in terms of contribution ratio was found to be positively correlated with the magnitude of force applied. In cases where stronger anchorage reinforcement is required, precision cuts is the superior method.

CONCLUSIONS

The utilization of microimplants in conjunction with CAs can facilitate the effective contribution ratio of molar distalization. However, it is important to note that complete elimination of anchorage loss is not achievable. To mitigate undesired movement, careful planning of anchorage preparation and overcorrection is recommended.

The incidence and severity of open gingival embrasures in adults treated with clear aligners and fixed appliances: a retrospective cohort study

BACKGROUND

To evaluate the incidence and severity of open gingival embrasures (OGEs) in adult patients treated with clear aligners and fixed appliances.

METHODS

Two hundred non-extraction adult subjects with less than 5 mm of crowding (mean age, 24.6 ± 3.8 years) were enrolled in this retrospective study. The subjects were divided into the clear aligner (n = 100) and fixed appliance group (n = 100). The intraoral photographs were utilized to determine the incidence of OGEs in the upper arch between maxillary central incisors, as well as the lower arch between mandibular central incisors. Crown overlap, crown shape, posttreatment root angulation, the distance from the interproximal contact point (ICP) to the alveolar bone crest (ABC) after treatment and interproximal enamel reduction (IPR) were determined in the two groups.

RESULTS

The incidence of OGEs between maxillary and mandibular central incisors after orthodontic treatment was 35.0% and 38.0% in the clear aligner group, respectively, significantly higher than that (18.0% and 24.0%) in the fixed appliance group (P < 0.05). The average area of an OGE after clear aligner treatment was larger both in the maxilla (0.16 ± 0.12mm²) and mandible (0.21 ± 0.24mm²) compared with that (0.05 ± 0.03mm² and 0.05 ± 0.06mm²) after fixed appliance treatment (P < 0.05). No difference was found regarding pretreatment crown overlap, crown shape, treatment duration, posttreatment root angulation, amount and distribution of IPR and the distance from ICP to ABC.

CONCLUSIONS

The incidence and severity of OGEs were higher in adults treated with clear aligners. Clinicians should be aware of the risk of OGEs during treatment with clear aligners.

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis

Introduction: Open gingival embrasure (OGE) is a common complication in adults following clear aligner therapy and the influence of gingival or alveolar bone biotype on OGE is of great concern. Unfortunately, due to the limited number of patients with clearaligner therapy and the clinical methods to distinguish the gingival biotype of patients being invasive, it is difficult to carry out clinical studies on the gingival or alveolar bone biotype of the OGE. In the meanwhile, the detailed biomechanics of the occurrence of OGE remains unknown. The goal of this study was to establish a new model to simulate the virtual space region, namely, the OGE region, to investigate the relationship between alveolar bone biotype and the occurrence of OGE, and explore potential biomechanical factors related to OGE.

Methods: The OGE region in the interproximal space was established using a filler with a very low modulus of elasticity (1 × 10−6 MPa). To illustrate the biomechanics of OGE more exhaustively, a line was created at the top of the alveolar crest along the proximal tooth root. FEA was then used to analyze the biomechanics of the surrounding tissues, the OGE region and the line at the top of the alveolar crest along the proximal tooth root of the central incisor under two different labial bone thicknesses (thick and thin) with an axial inclination of 80°, 90° and 100°.

Results: During intrusion of the incisors in clear aligner therapy, as inclination increased or bone tissue became thinner, the stress in the surrounding tissues [tooth root, alveolar crest, and periodontal ligament (PDL)] was greater. In the OGE region and interproximal alveolar crest, the strain increased with increasing inclination and labial bone thinning. The results from the line at the top of the alveolar crest along the proximal tooth root showed more detailed biomechanics: In all groups, stress and strain were focused on the mesial-labial alveolar crest. Interestingly, our results also demonstrated that when OGE occurs, other complications may arise, including root resorption and bone dehiscence.