Molar incisor hypomineralization (MIH): The "Why, What and How" of decision making for orthodontists.

Molar-incisor hypomineralization (MIH) presents a significant clinical challenge in orthodontics, with its complex etiology, variable presentation, and profound impact on enamel homeostasis. Utilizing Simon Sinek's "Golden Circle" method, this article systematically explores the implications of MIH within orthodontic practice. The "Why" emphasizes the critical need for orthodontists to understand MIH, given its prevalence and potential to disrupt treatment outcomes. MIH affects up to 40.2% of the global population, and its association with increased caries risk, hypersensitivity, and restorative failures necessitates an informed approach to management. The "What" section addresses the importance of recognizing the phenotypic variability of MIH and its influence on oral health-related quality of life. MIH impacts social and psychological well-being, particularly when anterior teeth are involved, and complicates orthodontic treatment due to challenges in bonding, banding, and restorative protocols. The "How" provides practical guidelines for orthodontic management, including diagnostic considerations, tooth restoration strategies, and the complexities of first permanent molar extractions. Strategic planning is essential to avoid complications such as mesial drift, overeruption, or space loss, with a multidisciplinary approach often required. This article highlights the importance of long-term monitoring and patient-centered care in managing MIH-affected teeth, underscoring the evolving nature of clinical protocols. By framing the discussion through the Golden Circle, this critical review offers a structured and impactful approach to understanding and addressing MIH within orthodontic contexts, aiming to enhance treatment outcomes and patient quality of life.

Are changes in malocclusion associated with adulthood psychosocial well-being?

INTRODUCTION: The purpose of this study was to investigate the longitudinal psychosocial effects of changes in malocclusion from adolescence to adulthood on oral health-related quality of life (OHRQOL), self-rated dental appearance, and overall life satisfaction. METHODS: The Dunedin Multidisciplinary Health and Development Study is a longitudinal birth cohort study of 1037 children born at Queen Mary Hospital, Dunedin, New Zealand, between April 1, 1972 and March 31, 1973. Data on their health and development, including dental examinations, has since been collected periodically. Malocclusion severity was measured using the Dental Aesthetic Index in participants aged 15 and 45 years (data collected at age 18 years was supplemented for data missing at age 15 years). Other data collected included clinically assessed oral health (dental caries and periodontal disease experience) and self-rated dental appearance, OHRQOL, life satisfaction, and personality traits. RESULTS: Malocclusion data were available for 868 participants in adolescence and 834 aged 45 years. For those with a severe handicapping malocclusion at 15 years old, 46.6% who received orthodontic treatment transitioned to a resolved (ie, mild-moderate) malocclusion when aged 45 years, whereas only 16.2% of those who did not receive orthodontic treatment made that transition. A transition to a worse malocclusion was associated with impacts on OHRQOL when aged 45 years in the subdomains of functional limitation, psychological discomfort, and physical disability as well as worse self-ratings of dental appearance, and these findings were held after adjusting for potential confounders. Malocclusion was not associated with overall life satisfaction. CONCLUSIONS: Maintenance of acceptable occlusion after orthodontic treatment requires a strong emphasis on achieving and maintaining excellent dental health and avoiding chronic oral conditions such as dental caries and tooth loss. The long-term benefits of orthodontic treatment may diminish by midlife unless good dental health is maintained. Orthodontists have the responsibility to raise awareness among their patients on how to maintain good oral health after orthodontic treatment.

Effect of post-printing curing time on cytotoxicity of direct printed aligners: A pilot study.

INTRODUCTION: The aim of this in vitro study was to examine the potential impact of different curing times of 3D-printed orthodontic aligners on their cytotoxicity. METHOD: Some 60 samples of aligner material were directly 3D printed using Tera Harz TC-85 DAC resin and randomly allocated to three different curing time groups (14, 24 and 50 min). Zendura FLX samples were used as control. The samples were incubated in saliva for 14 days, and then the supernatant was collected. Human gingival fibroblasts (HGF-1)-CRL2014 were used to evaluate potential cytotoxicity. Furthermore, HGF-1 cells were plated on the samples as well as on a glass control sample. After 72 h of growth, their viability was tested. RESULTS: Compared with the glass, only the 50-min curing time markedly reduced fibroblast cell growth. Additionally, a negative linear trend was observed between curing time and fibroblast growth. In comparison with the aligner control group, all samples, including the aligner control samples, exhibited a significant reduction in the viability of human fibroblasts when exposed to saliva. CONCLUSIONS: 3D directly printed aligners showed a cytotoxic effect similar to that of thermoformed conventional aligners in terms of fibroblasts growth. A linear trend was found between curing time and cells growth, indicating that directly printed aligners could exhibit higher cytotoxicity if exposed to a longer curing time. This dependence on curing time underscores the importance of following a strict manufacturing process.

Smile dynamics: A comparative study of Fijians and NZ Europeans.

BACKGROUND: The Fijian 'Bula Smile' is often described as the world's friendliest; however, its description remains anecdotal. OBJECTIVE: This study aimed to describe and compare the dynamics of Fijians' smiles with those of New Zealand Europeans. METHODS: An observational study was conducted on two ethnic groups, Fijians (FJ; N = 23) and New Zealand Europeans (NZ; N = 23), age- and gender-matched. All participants were asked to watch amusing videos, and their reactions were video recorded. The videos were analysed by software to assess the frequency, duration, intensity and genuineness of smiling episodes. Based on the Facial Action Coding System, Action Unit 6 (AU6-cheek raiser), Action Unit 12 (AU12-lip corner puller) and Action Unit 25 (AU25-lips apart) were assessed. Data were analysed by generalised linear models after adjusting for personality traits. RESULTS: Fijians smiled longer than New Zealand Europeans (+19.9%; p = .027). Mean intensity of AU6 (+1.0; 95%CIs = 0.6-1.5; p < .001), AU12 (+0.5; 95%CIs = 0.1-0.9; p = .008) and AU25 (+22.3%; 95%CIs = 7.3%-37.3%; p = .005) were significantly higher in FJ group than the NZ group. CONCLUSION: Smiling features of Fijians and New Zealanders showed objective differences, the most distinctive being a higher activation of the Duchenne's marker (AU6) in the Fijian group, which is regarded as a sign of smile genuineness.

Effect of carbamide peroxide on biomechanical properties of vacuum-formed retainers: A split-mouth randomized controlled trial.

OBJECTIVE: To investigate the effect of tooth whitening on biomechanical properties of vacuum-formed retainers (VFRs). METHODS: Using a split-mouth, randomised controlled trial design, thirty participants were randomly allocated to receive whitening on either the upper or the lower arch, using 10 % carbamide peroxide for two weeks. Biomechanical properties such as hardness, tensile strength, and surface roughness were assessed two weeks after whitening was completed. RESULTS: Tensile strength of the whitening arch (mean ± SD: 40.93 ± 3.96 MPa) was significantly lower than that of the control (47.40 ± 5.03 MPa) (difference 6.47 MPa, 95 % CI 4.51 - 8.42, p < 0.001). Hardness and internal roughness of the whitening arch (VHN = 14.63 ± 2.29 N/mm2 and Ra = 1.33 ± 0.35 µm, respectively) were significantly greater than those of the control (12.22 ± 1.86 N/mm2 and 0.96 ± 0.29 µm, respectively) (differences 2.41 N/mm2, 95 % CI 1.56 - 3.25, p < 0.001 and 0.37 µm, 95 % CI 0.23 - 0.51, p < 0.001, respectively). The whitening arch showed greater tooth colour change (ΔE = 6.00 ± 3.32) than the control (ΔE = 2.50 ± 1.70) (difference = 3.50, 95 % CI 2.43 - 4.56, p < 0.001). CONCLUSIONS: Based on this short-term study, marked tooth colour change was achieved by whitening with VFRs as the whitening trays, but this changed the VFRs' biomechanical properties, including a decrease in tensile strength and an increase in hardness and internal roughness. CLINICAL SIGNIFICANCE: The application of carbamide peroxide in VFRs may compromise their mechanical properties.

The effect of passive clear aligners on masticatory muscle activity in adults with different levels of oral parafunction.

BACKGROUND: There is limited knowledge of the possible side-effects of clear aligners on jaw function. OBJECTIVES: To determine the short-term effect of passive clear aligners (PCAs) on masticatory muscle activity (MMA), occlusal discomfort (OD) and temporomandibular disorder (TMD) symptoms in adults with different levels of self-reported oral parafunction. MATERIALS AND METHODS: Participants were screened for oral parafunctional behaviours using the oral behavioural checklist. Respondents in ≥85th and ≤15th percentiles were invited to participate and allocated to a high (HPF: N = 15) or low (lower parafunction [LPF]: N = 16) parafunction group. Participants underwent a TMD clinical examination; somatisation and somatosensory amplification were assessed by questionnaires; OD and stress were assessed by visual analogue scales. While wearing PCAs, awake-time MMA was assessed three times over 9 days using a wearable electromyography device, along with OD, stress and TMD symptoms. RESULTS: The wearing of PCAs was associated with a significant decrease in mean contraction episode amplitude in both groups (p = 0.003). OD levels increased and remained raised in all participants after insertion of the PCAs (p < 0.001), more so in the HPF group (p = 0.048). The HPF group had higher somatisation scores (p = 0.006) and reported more TMD symptoms at all time points (p ≤ 0.004). No significant changes in stress or TMD symptoms were found in either group during the study period. CONCLUSIONS: PCAs were associated with a decrease in MMA in all participants. HPF individuals had greater somatisation and reported greater discomfort when wearing PCAs than LPF individuals.

Wearables for personalized monitoring of masticatory muscle activity - opportunities, challenges, and the future.

Wearable devices are worn on or remain in close proximity of the human body. The use of wearable devices specific to the orofacial region is steadily increasing. Orofacial applications of wearable devices include supplementing diagnosis, tracking treatment progress, monitoring patient compliance, and understanding oral parafunctional behaviours. In this short communication, the role of wearable devices in advancing personalized dental medicine are highlighted with a specific focus on masticatory muscle activity monitoring in naturalistic settings. Additionally, challenges, opportunities, as well as future research areas for successful use of wearable devices for precise, personalized care of muscle disorders are discussed.

The effect of surface roughening of orthodontic elastomers on hydrophobicity and in vitro adherence of Streptococcus gordonii.

OBJECTIVES: Biofilm formation around orthodontic appliances causes gingivitis, enamel decalcification and caries. Bacteria adhere less readily to superhydrophobic surfaces. The aim of this study was to determine whether a superhydrophobic surface could be generated on orthodontic elastomers by surface modification in order to reduce bacterial adhesion. MATERIALS AND METHODS: Orthodontic elastomers were modified with sandpapers of various grit sizes (80-600 grit). Surface roughness of the modified and unmodified surfaces was assessed qualitatively with scanning electron microscopy and quantitatively with confocal microscopy. Water contact angles were measured with a goniometer to quantify hydrophobicity. Measurements were performed on unextended elastomers (100% original length) and elastomers extended to 150%, and 200% of the original length. Adhesion of Streptococcus gordonii to saliva coated elastomers was measured by counting colony forming units on agar plates. RESULTS: Abrasion with different sandpapers produced elastomers with surface roughness (Ra) ranging from 2 to 12 µm. Contact angles followed a quadratic trend with a maximum contact angle of 104° at an Ra of 7-9 µm. Average water contact angles, when viewed perpendicular to the direction of extension, decreased from 99° to 90° when the extension was increased from 100% to 200% and increased from 100° to 103° when viewed parallel to the direction of extension. Bacterial adhesion increased as roughness increased and this effect was more pronounced with elastomer extension. CONCLUSION: The surface roughness of orthodontic elastomers influences both their hydrophobicity and bacterial adhesion. Superhydrophobicity of elastomers could not be achieved with sandpaper abrasion.

An orthodontic tooth brushing technique to enhance oral hygiene in patients wearing fixed orthodontic appliances: A randomized controlled trial.

BACKGROUND: An effective tooth brushing technique is essential in maintaining oral hygiene, especially for patients wearing fixed orthodontic appliances. Traditional tooth brushing techniques are mainly designed for the general population without orthodontic appliances, which may not account for the oral condition of orthodontic patients due to the increased biofilm formation. The aim of this study was to design an orthodontic tooth brushing technique and compare its effectiveness with the traditional modified Bass technique. METHODS: Sixty patients wearing fixed orthodontic appliances were included in this two-arm paralleling randomized controlled trial. Thirty patients were assigned to the modified Bass technique group and 30 patients were assigned to the orthodontic tooth brushing technique group. The orthodontic tooth brushing technique involved a biting motion on the head of toothbrush in order to place the toothbrush bristles behind the archwires and around the brackets. Plaque index (PI) and gingival index (GI) were used to assess oral hygiene. Outcome measurements were taken at baseline and 1 month after the intervention. RESULTS: The new orthodontic tooth brushing technique significantly reduced PI (average PI reduction = 0.42 ± 0.13), especially in the gingival (0.53 ± 0.15) and interproximal (0.52 ± 0.18) areas (p < 0.05 for all). No significant reduction was found for the GI (p > 0.05 for all). CONCLUSION: The new orthodontic tooth brushing technique showed a promising result in reducing PI in patients wearing fixed orthodontic appliances.

Malocclusion severity and smile features: Is there an association?

INTRODUCTION: This observational study investigated the relationship between malocclusion and smiling. METHODS: Adolescents and young adults (n = 72; aged 16-25 years) were identified according to their Dental Aesthetic Index (DAI) and allocated to 3 groups: (1) malocclusion group (n = 24; DAI ≥31), (2) retention group (n = 24; pretreatment DAI ≥31) with a prior malocclusion that had been corrected by orthodontic treatment, (3) control group with no-to-minor malocclusion (n = 24; DAI ≤25). Participants were requested to watch an amusing video. Based on the Facial Action Coding System, automated pattern recognition was used to detect smile episodes and assess their frequency, duration, genuineness, intensity, and extent of tooth show. Demographics, Big Five personality dimensions, and self-perceived smile esthetics-related quality of life were collected from all participants via questionnaires. Data were analyzed by mixed-model analysis and adjusted for possible confounders. RESULTS: Patients from the malocclusion and retention groups smiled significantly less than participants from the control group, with the duration of smiles and smiling time being around half those of control subjects. Smile genuineness, smile intensity, and teeth shown did not differ across groups. Personality traits did not differ significantly among the 3 groups, whereas the malocclusion group scored around 30% less for dental self-confidence than the other 2 groups. CONCLUSIONS: Patients with severe malocclusion tend to smile less, but the features of their smiles are similar to those without malocclusion. A lower propensity to smile in patients with a corrected malocclusion may persist after orthodontic treatment.

Immediate effect of clear aligners and fixed appliances on perioral soft tissues and speech.

OBJECTIVES: To compare the immediate three-dimensional (3D) perioral soft-tissue changes and impact on speech induced by clear aligners and fixed appliances. MATERIALS AND METHODS: In this repeated-measure experimental study, stereophotogrammetric 3D photographs of 40 participants were recorded before and immediately after the introduction of clear aligners and fixed appliances. The 3D surface meshes were registered to quantify changes in the direction and magnitude of nine soft tissue landmarks located on the upper and lower lips. Self-reported speech disturbance was evaluated using a questionnaire. Data were analysed using repeated-measures analysis of variance. RESULTS: In the vertical plane, the clear aligners induced inferior displacement (range 0.4-1.5 mm) for all nine landmarks (P < .01), whereas fixed appliances induced inferior displacement only of A-point (0.4 ± 0.9 mm), right crista philtri (0.5 ± 1.1 mm) and left crista philtri (0.7 ± 1.1 mm). The clear aligners induced greater vertical changes than fixed appliances for all landmarks (P < .05). In the sagittal plane, both clear aligners and fixed appliances slightly advanced all perioral landmarks, except subnasale. Fixed appliances caused greater changes than clear aligners for right cheilion (+0.8 mm), left cheilion (+0.8 mm) and labrale inferius (+0.9 mm) (P < .01). Both orthodontic appliances had a significant self-perceived effect on speech, with clear aligners affecting speech to a greater degree. CONCLUSION: Clear aligners and fixed appliances produced immediate effects on perioral soft tissues, which are most evident in the vertical plane for clear aligners, and in the sagittal plane for fixed appliances. Speech was affected by both appliances.

Three-dimensional digital assessment of typodont activations.

OBJECTIVES: Wax typodonts are widely used as pre-clinical teaching tools to test and research the complex force systems created by archwire activations, however, a limitation is the inability to quantify the resultant statically indeterminate tooth movements. The aim of this study was to develop an analogue-to-digital typodont system to quantify the effects of archwire activations on individual typodont teeth in three dimensions. METHODS: The typodont system was developed using CAD/CAM technology. Posterior expansion, squared, tapered, asymmetrical arch forms and reversed curve of Spee activations were tested with three repeats. The resulting three-dimensional movements of individual typodont teeth were assessed with six degrees of freedom (df). Cartesian coordinate systems were set for each tooth. Mesio-distal, bucco-lingual and intrusive-extrusive movements were assessed as changes in the location of the geometrically estimated centre of resistance in the x, y and z axes, respectively. Torque, tip and rotation movements were assessed as the rotations around the mesio-distal, bucco-lingual and intrusive-extrusive axes, respectively. RESULTS: Individual typodont tooth displacements from each activation could reliably be described with six df. The transversal-to-sagittal movement ratio ranged from 2:1 to 7:1, depending on the activation. Asymmetrical arch form activations caused a midline shift and affected the lateral overjet. Reversing the curve of Spee led to intrusion of incisors and second molars, extrusion of premolars and first molars and pronounced first and third order effects. CONCLUSION: The digital typodont system is a promising teaching tool. The tested activations have implications in three dimensions, which should be considered when planning tooth movements.

Predictability of lower incisor tip using clear aligner therapy.

BACKGROUND: Uprighting incisors is particularly important with clear aligner therapy as incisor tip determines the mesio-distal space needed in the arch, and consequently the fit of the aligner. The objective of this study was to investigate the accuracy of ClinCheck® software to predict lower incisor tip by comparing digitally prescribed movements with actual clinical outcomes and to determine whether the presence of a vertically orientated rectangular composite attachment influences the efficacy of incisor tip. METHODOLOGY: This retrospective study included 66 lower incisors from 42 non-extraction adult patients treated using the Invisalign® appliance. Twenty-one incisors had vertical attachments, while 45 incisors did not have any attachments. Lower incisor tip was measured at T0 (pre-treatment), T1 (predicted post-treatment) and T2 (achieved post-treatment) on digital models using metrology software. The change in position from T0 to T1 and T0 to T2 was measured from the estimated centre of resistance (CRes) of each tooth. The estimated centre of rotation was plotted relative to the CRes to describe the type of orthodontic tooth movement (OTM) predicted and achieved. RESULTS: Predicted incisor tip and achieved incisor tip were positively correlated (R2 = 0.55; p < 0.001). For every degree of tip planned 0.4 degrees of tip was achieved. The presence of an attachment resulted in 1.2 degrees greater tip (F = 3.7; p = 0.062) and 0.5 mm greater movement of the predicted apex of the tooth (F = 4.3; p = 0.042) compared with the no attachment group. The type of OTM achieved differed from the type predicted. Sixty-seven percent of incisors investigated were predicted to move by root movement, while 46% achieved this type of movement. CONCLUSIONS: The amount of lower incisor tip achieved was on average substantially less than the ClinCheck® displayed. Vertically orientated rectangular attachments are recommended where large root movement is planned, and their presence slightly improves apex movement.

Automated detection of smiles as discrete episodes.

BACKGROUND: Patients seeking restorative and orthodontic treatment expect an improvement in their smiles and oral health-related quality of life. Nonetheless, the qualitative and quantitative characteristics of dynamic smiles are yet to be understood. OBJECTIVE: To develop, validate, and introduce open-access software for automated analysis of smiles in terms of their frequency, genuineness, duration, and intensity. MATERIALS AND METHODS: A software script was developed using the Facial Action Coding System (FACS) and artificial intelligence to assess activations of (1) cheek raiser, a marker of smile genuineness; (2) lip corner puller, a marker of smile intensity; and (3) perioral lip muscles, a marker of lips apart. Thirty study participants were asked to view a series of amusing videos. A full-face video was recorded using a webcam. The onset and cessation of smile episodes were identified by two examiners trained with FACS coding. A Receiver Operating Characteristic (ROC) curve was then used to assess detection accuracy and optimise thresholding. The videos of participants were then analysed off-line to automatedly assess the features of smiles. RESULTS: The area under the ROC curve for smile detection was 0.94, with a sensitivity of 82.9% and a specificity of 89.7%. The software correctly identified 90.0% of smile episodes. While watching the amusing videos, study participants smiled 1.6 (±0.8) times per minute. CONCLUSIONS: Features of smiles such as frequency, duration, genuineness, and intensity can be automatedly assessed with an acceptable level of accuracy. The software can be used to investigate the impact of oral conditions and their rehabilitation on smiles.

Prevalence of halitosis among young adults in Dunedin, New Zealand.

OBJECTIVES: To investigate the prevalence of halitosis in young adults. METHODS: Young adults (n = 372; mean age = 21.0 ± 2.6 years old, range = 18-30 years) in Dunedin, New Zealand, were recruited into the cross sectional study after providing informed consent. The prevalence of halitosis was determined using both objective measurements (parts per billion [ppb] volatile sulphur compounds [VSCs] in the exhaled air) and subjective measurements (self-reported halitosis questionnaire, tongue coating index, and organoleptic assessment). RESULTS: Volatile sulphur compounds measurements indicated that the prevalence of halitosis (values ≥140 ppb) was 31.2%; 25.6% of participants self-reported halitosis. The organoleptic assessment revealed that 14.3% of the participants had a score of ≥2. A positive correlation was found between the VSC measurements and organoleptic assessment (p < 0.05). No significant relationship was found between self-reported halitosis and either organoleptic assessment or VSC measurements. Self-reported dry mouth, smoking, oral hygiene index, DMFT index, and tongue coating score were significantly associated with the organoleptic assessment (p < 0.05). The self-reported dry mouth, mouth breathing and tongue coating score were significantly associated with the VSC scores (p < 0.05). CONCLUSION: Halitosis, as represented by VSC, was found in 31.2% of the participants. VSC scores and organoleptic assessment were positively correlated. There was no significant relationship between self-reported halitosis and either organoleptic assessment or VSC measurements.

Effect of prior knowledge about treatment on cephalometric measurements.

OBJECTIVE: We hypothesised that prior knowledge of details for a growth modification treatment influences cephalometric measurements and results in a detectable bias. DESIGN: Observational study. SETTING: University teaching facility. METHODS: Six orthodontic residents assessed 48 lateral cephalograms taken before and after functional appliance treatment from 24 patients. The residents assessed six cephalometric measurements, (Cd-Pog, Cd-Me, Ar-Pog, Ar-Me, Go-Me, SNB) over three separate sessions, in either a random concealed order or as matched pairs with information about treatment and time disclosed. RESULTS: When information was disclosed, five out of the six cephalometric measurements were significantly higher that the corresponding cephalometric measurements taken randomly with undisclosed information. The bias was in the range of 1.6-3.2 mm for linear measurements and was 1.1° for SNB. CONCLUSION: Disclosing treatment information does introduce systematic errors in cephalometric measurements. Cephalometric analysis in orthodontic clinical research should be carried out by assessors who are blinded to treatment details, to minimise risk of bias.

A qualitative meta-synthesis of research into patients' past experiences and perceptions of orthodontic treatment outcomes.

BACKGROUND: There is a growing body of evidence emphasizing the importance of research into patient-centred experience in orthodontics. Benefits following orthodontic treatment are mainly related to improved aesthetics and psychosocial outcomes. However, treatment experience from the perspective of orthodontic patients is yet to be fully understood. OBJECTIVE: To understand the past experiences and current perceptions of treatment outcomes of orthodontic patients. STUDY DESIGN: A qualitative meta-ethnography. SELECTION CRITERIA: Qualitative studies and mixed-methods articles with a distinct qualitative component presenting patients' perception of outcomes and overall experiences after an active course of orthodontic treatment were included. SEARCH METHODS: Comprehensive electronic searches were conducted in MEDLINE, Scopus, Web of Science, PsycINFO, and EMBASE up to May 2021, supplemented by grey literature and manual searches. DATA COLLECTION AND ANALYSIS: Two independent reviewers were involved in study selection, data extraction, and quality appraisal. The Critical Appraisal Skills Programme tool for qualitative research was used to assess the quality of included studies. Analysis of data was conducted using meta-ethnographic methods. RESULTS: Out of 801 retrieved search hits, six studies fulfilled the inclusion criteria and were included in the synthesis. The analysis revealed three main themes and associated sub-themes: (1) Reflection on the past treatment experience, (2) Patient satisfaction with treatment outcomes, and (3) Learning to live with retainers. LIMITATIONS: Results express patients' opinions shortly after treatment, and the long-term impact of orthodontic treatment is yet to be understood. CONCLUSIONS: Orthodontic patients mainly viewed their experiences and treatment results positively. Desirable aesthetic outcomes, psychosocial outcomes, and satisfaction with smiles were often reported in the studies reviewed. However, some barriers to optimal experiences were noticed concerning orthodontic retention. REGISTRATION: PROSPERO (CRD42020180121).

Changes in incisor relationship over the life course - Findings from a cohort study.

OBJECTIVE: The aim of this longitudinal cohort study was to investigate the changes in incisor relationship over three decades from adolescence to mid-adulthood. MATERIALS AND METHODS: The sample included 1,037 children (48.4% female) born between April 1972 and March 1973 from the longitudinal birth cohort Dunedin Multidisciplinary Health and Development Study. Overjet and overbite values were assessed at age 15 and 45 years and entered in a regression model as outcome variables. Baseline occlusal variables, sex, history of orthodontic treatment, periodontal data recorded at age 38, and self-reported oral parafunction and orthodontic treatment history recorded at age 45 were entered as covariates in the regression analysis. RESULTS: Regression modelling showed that overjet/overbite category (high or low) at age 15 tends to predict overjet/overbite category at age 45, with overjet become slightly larger (around +0.5 mm) and overbite slightly lower (-0.5 mm) over time. Study members with self-reported tooth clenching had a slighter greater overbite (+0.3 mm) at age 45 than those who did not. Additionally, those with signs of periodontal disease at age 38 had a slightly larger overjet (+0.5 mm) at age 45 than those without disease. Sex differences were demonstrated with females having 0.6 mm larger overjet, and 0.4 mm overbite at age 45. CONCLUSIONS: Overall, overjet values tend to be higher during mid-adulthood than during adolescence, while the converse is true for overbite. There appears to be a degree of sexual dimorphism in overjet and overbite values later in life. CLINICAL SIGNIFICANCE: Incisor relationships change during the life course and are related to ageing, sex, periodontal health, and parafunctional habits. Clinicians and educators should be aware of these changes when making treatment decisions that alter incisor relationship.

The effect of ligation methods on biofilm formation in patients undergoing multi-bracketed fixed orthodontic therapy - A systematic review.

BACKGROUND: Many modifications to fixed orthodontic appliances have been introduced to manage biofilm formation. The aim of this review was to investigate elastomeric ligation in comparison with stainless steel ligation and self-ligation with regard to microbiological and clinical indicators of biofilm formation in patients wearing multi-bracketed fixed orthodontic appliances. METHODS: The MEDLINE and the EMBASE databases were searched up to February 2021 and supplemented by additional manual searches of bibliographies. Parallel-group and split-mouth randomized controlled trials (RCTs) comparing different ligation methods were identified. The Cochrane Risk of Bias-2 tool was applied to assess the quality of evidence. RESULTS: A total of 11 RCTs were included in this review. Nine RCTs compared self-ligation and elastomeric ligation; two compared elastomeric ligation and stainless steel ligation. The included studies had either some concerns or were at a high risk of bias. Qualitative assessment of the studies identified that there were no significant differences in biofilm formation between elastomeric ligation and self-ligation, but that stainless steel ligation was less susceptible to biofilm formation than elastomeric ligation. CONCLUSIONS: There were no significant differences between self-ligation and elastomeric ligation for biofilm formation in patients wearing multi-bracketed fixed orthodontic appliances. Stainless steel ligation may accumulate less biofilm than elastomeric ligation; however, the clinical significance of the difference could not be evaluated. Further high-quality studies are required in order to determine which ligation method is better for managing biofilm formation in patients wearing multi-bracketed fixed orthodontic appliances.