Mandibular second molar extraction: A retrospective cohort study of spontaneous occlusal changes in adolescent patients.

OBJECTIVES: Evaluate long-term spontaneous occlusal changes following L7 extraction in adolescent patients. MATERIALS AND METHODS: Study models of 144 participants (63 males, 81 females) retrospectively assessed prior to L7 extraction (9-16 years old; T1) and following L8 eruption (14-25 years old; T2). All received upper fixed appliances. A sub-group (n = 86) received no lower fixed appliances and acted as controls. Occlusal changes were compared between treatment (lower fixed appliance) and control (no lower fixed appliance) groups using PAR index. At T2, L8 occlusal outcome was assessed using ABO grading system. RESULTS: Mean follow-up period 6 (SD 2) years. At T1, lower scores observed in control group for Lower Anterior (P < .001), Midline (P = .033) and Lateral Segments (P = .040) components. At T2, lower scores continued being observed in control group for Midline (P < .001) and Lateral segment (P = .019) components. Higher decrease in Lower Anterior PAR scores observed in treatment group (<.001) with comparable scores between groups at T2 (P = .057). Similar PAR score changes between groups for Lateral Segments, Overjet and Overbite components. At T2, no significant difference observed in Total PAR score reduction between control (83%) and treatment (82%) groups. Good-to-acceptable occlusal outcome of the L8 observed in 81.55% of cases at T2 with no difference between groups. CONCLUSION: In growing patients with mild mandibular crowding, extraction of L7 followed by upper fixed appliance therapy, leads to favourable occlusal changes over a 6-year follow-up period, with or without lower fixed appliance therapy, being an alternative extraction protocol where lower fixed appliance therapy is not recommended.

Stability, survival, patient satisfaction, and cost-minimization of CAD/CAM versus conventional multistranded fixed retainers in orthodontic patients: a 2-year follow-up of a two-centre randomized controlled trial.

BACKGROUND: CAD/CAM (computer-aided design/computer-aided manufacturing) fixed retainers (FRs) as an alternative to multistranded FRs to maintain orthodontic treatment outcome. OBJECTIVES: The primary aim was to compare CAD/CAM versus conventional multistranded FRs in terms of stability until 2 years. Secondary outcomes were failure rates, patient satisfaction, and cost-minimization. TRIAL DESIGN: 2-arm parallel, two-centre randomized controlled trial. METHODS: Patients were randomized to CAD/CAM or conventional FRs in both arches, in a 1:1 ratio and blocks of four. Allocation concealment was secured by using sequentially numbered envelopes. Patients were blinded. FRs were bonded at the end of treatment, and patients were recalled after 12 and 24 months. First-time retainer failures were recorded and digital impressions were taken. Arch widths and lengths, as well as Little's Irregularity Index (LII), were measured. Additionally, patients answered satisfaction questionnaires. Linear mixed models were applied for measurements and patient satisfaction. Survival analyses were estimated with Kaplan-Meier curves, along with Cox-regression modelling. Cost-minimization analysis was undertaken. RESULTS: One hundred and eighty-one patients were randomized (98 in Centre 1, and 83 in Centre 2): 90 in CAD/CAM and 91 in conventional group. One hundred and fifty three patients attended T24 follow-up. There were no significant differences in LII and arch dimensions between groups for failure-free patients. Within 24 months, 34% maxillary CAD/CAM FRs and 38% maxillary conventional FRs failed, along with 42% mandibular CAD/CAM FRs and 40% mandibular conventional FRs, with no significant difference in survival between groups (hazard ratios conventional to CAD/CAM: maxillary arch: 1.20 [P = 0.46], mandibular arch: 0.98 [P = 0.94]). There were no significant differences in patient satisfaction between groups. No harms were observed. Cost-minimization analysis showed that CAD/CAM FRs were slightly cheaper than conventional FRs. CONCLUSIONS: There were no clinically significant differences in LII, arch widths, and lengths between CAD/CAM and conventional FRs after 24 months. There were no differences in failures and patient satisfaction between groups. CAD/CAM FRs were slightly cheaper than conventional FRs. TRIAL REGISTRATION: ClinicalTrials.gov NCT04389879.

Elemental composition, corrosion resistance and mechanical properties of computer-aided design and computer-aided manufacturing fixed retainers versus conventional fixed retainers.

PURPOSE: To investigate the elemental composition, corrosion resistance, and mechanical properties of computer-aided design and computer-aided manufacturing (CAD-CAM) retainers versus conventional fixed retainers (FRs). METHODS: Eight different retainer wires were investigated. Energy dispersive X-ray spectroscopy was used to determine the elemental composition. Leakage was analysed according to ISO 10271:2020 guidelines. Hardness was tested using the Vickers method with a load of 0.3 kg. The tensile force and tensile strength were evaluated. Multiple comparisons among wires of hardness, tensile force, and strength were conducted using the Welch t-test, with Bonferroni correction. RESULTS: Nickel was present in all wires. The CAD-CAM-FR wire, which contained more nickel than the other wires, had no measurable leakage. The gold-plated wires had the highest total leakage, but did not exceed the ISO standard limit. The hardness of the stainless-steel twisted wires was the highest and that of the CAD-CAM-FR wire was the lowest. The tensile strength of the CAD-CAM-FR wire was significantly lower than that of the other wires and similar to the other twisted-wire retainers. CONCLUSION: The CAD-CAM-FR wire is likely to have high corrosion resistance and flexibility due to its low hardness.

Effect of chlorhexidine mouthwash on gingival health around orthodontic miniscrew implants: A pilot placebo-controlled randomized trial.

OBJECTIVE: This randomized controlled trial (RCT) aims to investigate the short-term effects of chlorhexidine mouthwash (MW) on gingival health surrounding orthodontic miniscrew implants (OMIs) and their overall survivability. MATERIALS AND METHODS: Thirty-two participants (mean age, 22.8 years) undergoing fixed orthodontic appliance treatment after maxillary premolar extraction were randomly allocated in a parallel fashion to either receive (1) MW with an active component of chlorhexidine or (2) a placebo. Each participant received two maxillary buccal OMIs for anchorage reinforcement purposes. Participants were assessed for their gingival oral health status around all inserted OMIs and had their OMI survivability recorded at three time points; T1 = 1 month, T2 = 3 months, and T3 = 6 months after OMI placement. A Kaplan-Meier plot was used to estimate the survival function of OMIs. RESULTS: All randomized participants completed the follow-up period. In terms of gingival oral health, there were no statistically significant differences at any time point between the chlorhexidine MW group and the placebo-controlled group (P > .05). One OMI was lost in the chlorhexidine MW group and another two OMIs in the control group. There was no significant difference between both groups in terms of survivability (P = .585). CONCLUSION: The use of chlorhexidine MW does not seem to have a significant clinical impact on gingival health around OMIs or their survivability in this pilot study.

Stability, survival, and patient satisfaction with CAD/CAM versus conventional multistranded fixed retainers in orthodontic patients: a 6-month follow-up of a two-centre randomized controlled clinical trial.

OBJECTIVES: The primary aim of this two-arm parallel two-centre randomized controlled trial was to compare computer-aided design and computer-aided manufacturing (CAD/CAM) versus conventional multistranded fixed retainers (FRs) in terms of stability over 6 months. Secondary outcomes were failure rates and patient satisfaction. METHODS: Patients were randomized to CAD/CAM or conventional FRs in both arches, in 1:1 ratio and blocks of four. Allocation concealment was secured by using sequentially numbered envelopes. Patients were blinded. Retainers were bonded at the end of orthodontic treatment (T0), and patients were recalled after 1 (T1), 3 (T3), and 6 (T6) months. First-time retainer failures were recorded and digital impressions were taken. Arch widths and lengths, as well as Little's Irregularity Index (LII), were measured. Additionally, patients answered satisfaction questionnaires. Linear mixed models were applied for measurements and patient satisfaction. Survival analyses were estimated with Kaplan-Meier curves, along with Cox-regression modelling. RESULTS: One hundred and eighty-one patients were randomized (98 in Centre 1, and 83 in Centre 2): Ninety in the CAD/CAM group and 91 in the conventional group. Three subjects dropped out at baseline, as they did not attend any of the follow-up appointments.168 patients attended the T6 visit. There were no significant differences in arch dimensions between T0 and T6, whilst the LII was different only in the CAD/CAM group (mean difference: 0.2 mm; 95% confidence interval: 0.1 to 0.4; P < 0.001). Within 6 months, 39 upper retainers (19 out of 88 CAD/CAM and 20 out of 90 conventional retainers) and 52 lower retainers failed (26 out of 88 CAD/CAM and 26 out of 90 conventional retainers), with no significant difference between the survival of both types of retainers (hazard ratios conventional to CAD/CAM: upper arch: 0.99 [P =0.99], lower arch: 0.93 [P = 0.80]). There were no significant changes in patient satisfaction between the groups. No harms were observed. CONCLUSIONS: There were no clinically significant differences in LII, arch widths and lengths between CAD/CAM and conventional retainers after 6 months. There was no difference in failures and in patient satisfaction between both types of FRs. REGISTRATION: ClinicalTrials.gov NCT04389879.

Survey on retention procedures and use of thermoplastic retainers among orthodontists in Norway, Sweden, and Denmark.

BACKGROUND: Orthodontic retention is the most important factor after successful orthodontic treatment. The use of thermoplastic retainers has increased in recent years, but information is lacking about the product materials and orthodontists' awareness of the products they use. The aim of this survey was to map the retention protocols among Scandinavian orthodontists, particularly their use of thermoplastic retainers. Furthermore, the aim was to investigate their knowledge of thermoplastic materials and record any possible adverse effects. METHODS: An online questionnaire was prepared, and 667 orthodontists in Norway, Sweden, and Denmark were invited to take the survey. The survey was sent to all members of the national orthodontic associations using Nettskjema in Norway and Microsoft Forms in Sweden and Denmark. Data were collected anonymously and analyzed using chi-square and correlation coefficients. RESULTS: Of the 667 orthodontists, 432 (64%) responded (59% female). The most common retention protocol (51%) was fixed retainer in both maxilla and mandible and thermoplastic retainer in the maxilla. Two-thirds of the orthodontists were unaware of the thermoplastic material used, and 58% did not acquire knowledge of the materials. Only 1% of the respondents had registered adverse reactions to thermoplastic retainers, and none were aware of the type of material that was used. CONCLUSIONS: Scandinavian orthodontists use similar retention protocols, with the most common being fixed retainer in the mandible and dual retention, fixed, and thermoplastic retainer in the maxilla. Orthodontists' knowledge about thermoplastic materials was insufficient, but adverse effects related to thermoplastic retainer use were rare.

Patient-Reported Outcome Measures on Oral Hygiene, Periodontal Health, and Treatment Satisfaction of Orthodontic Retention Patients up to Ten Years after Treatment-A Cross-Sectional Study.

Background: This cross-sectional study evaluated patient-reported outcome measures (PROMs) on (1) oral hygiene, (2) periodontal health, (3) retainer failure, (4) orthodontic treatment satisfaction, and (5) outcome satisfaction in orthodontic retention patients. The purpose of the study was to evaluate whether orthodontic retention treatment is associated with patient-reported outcome measures on oral hygiene, periodontal health, and treatment satisfaction. Methods: A ten-item questionnaire on the five PROMs was conducted among 211 consecutive retention patients up to ten years following orthodontic treatment. Linear regression models were computed to detect possible associations between the PROMs and retention treatment or patient characteristics. Results: The presence of a fixed lingual retainer was not associated with the reduced ability to perform oral hygiene, self-perceived periodontal health, or orthodontic outcome satisfaction. Older patients were more content with the orthodontic treatment result (p < 0.05). Patients with fixed lingual retainers in the mandible were less satisfied with the course of orthodontic treatment (p < 0.05). Smokers more often reported gingival bleeding (p < 0.05). Females reported increased gingival recessions (p < 0.05) and perceived their teeth as longer than before treatment (p < 0.05). Longer orthodontic treatment duration corresponded to retainer failure (p < 0.05). Conclusions: In general, long-term orthodontic retention patients were satisfied with orthodontic treatment. These patients reported the satisfactory ability to perform adequate oral hygiene and periodontal health, and they communicated a high degree of treatment and outcome contentment. However, patients with a retainer in the mandible were less satisfied with orthodontic treatment.

Presence and Maturation Dynamics of Mandibular Third Molars and Their Influence on Late Mandibular Incisor Crowding: A Longitudinal Study.

The objective of this study was to investigate the relationship between the absence, presence and dynamics of mandibular third molar development and the occurrence and amount of late mandibular incisor crowding. Dental plaster casts and panoramic radiographs of 72 orthodontically untreated subjects from the Nittedal growth study, Norway were analyzed. The subjects were recalled for a checkup at 12, 15, 18 and 21 years of age. Mandibular incisor crowding was assessed using Little's irregularity index and dental maturation of the third molars by the Cameriere's index. The majority of the subjects (64%) had ≥1 mm increase in irregularity; 22% experienced an increase of 0.1-0.9 mm and 14% had unchanged or decreased irregularity. Incisor irregularity increased with age, regardless of absence or presence of third molars. The amount of change in incisor irregularity from 12 to 21 years did not differ significantly between subjects with hypodontia of third molars, extraction and those with third molars present. No differences were observed between erupted, unerupted or impacted third molars. No correlation was found between the amount of change in irregularity and maturation of the third molars. In conclusion, occurrence and amount of mandibular late incisor crowding is not significantly influenced by the presence of mandibular third molars or their development dynamics.

Incisor and profile alterations in extraction cases treated with standard Edgewise and pre-adjusted appliances: A controlled before-and-after study.

BACKGROUND: Even though treatment of Class II malocclusion with premolar extractions and incisor retraction might affect incisor inclination and soft tissue profile, the effects of bracket prescription on this have not been thoroughly assessed. METHODS: Fifty patients (mean age: 13.6 years; 34% male) receiving extraction-based treatment with either standard Edgewise or pre-adjusted appliances were included. Between-group differences in the incisor inclination assessed with lateral cephalograms were analyzed statistically with linear/logistic regression at 5%. RESULTS: Treatment-induced changes included retroclination of the upper/lower incisors (-3.0° and -2.0°, respectively), retraction of the upper/lower incisors (-3.4 mm and -1.5 mm, respectively), retraction of the upper/lower lip (-2.1 mm and -2.0 mm, respectively), and enlargement of the nasolabial angle (+1.6°). Analysis of the data adjusting for confounders indicated that the pre-adjusted group, after treatment, had larger inclination of the upper or lower incisors (+3.2° and +4.5°, respectively), more prominent upper incisors relative to the facial plane (+1.3 mm), and smaller interincisal angle (-7.3 or -7.7°). Post-treatment upper incisor inclination fell within the cephalometric norm significantly more in the pre-adjusted than in the standard Edgewise group (odds ratio 4.3; 95% confidence interval 1.1-16.6). No differences were found in lower incisor prominence, upper/lower lip prominence, or nasolabial angle. CONCLUSIONS: Pre-adjusted appliances were associated with increased inclination of the upper and lower incisors, with more prominent upper incisors, and with more acute interincisal angle after retraction compared with standard Edgewise appliances. However, such differences did not translate in greater retraction of the upper/lower lips and greater nasolabial angle.

Periodontal status in long-term orthodontic retention patients up to 10 years after treatment - a cross-sectional study.

OBJECTIVE: To assess periodontal status in long-term orthodontic retention patients and investigate possible risk indicators. MATERIALS AND METHODS: Plaque index (PI), gingival index (GI), probing pocket depth (PPD), gingival recessions (GR) and calculus were recorded in 211 patients with or without fixed retainers. RESULTS: Periodontal parameters were within the limits of clinically healthy periodontium. The use of fixed retainers was associated with higher PI in the maxilla (ß = 1.10 [0.37]; p <.05). Older age was associated with higher PI in the mandible (ß = 0.27 [0.11]; p <.05). Smoking was associated with gingival bleeding on both palatal (ß = 0.63 [0.16]; p < .01) and labial sides in the maxilla (ß = 0.46 [0.20]; p <.05). Smoking was also associated with increased prevalence of GR in the mandible (ß = 0.24 [0.07]; p <.01), while use of snuff had similar effect on the labial side in the maxilla (ß = 0.35 [0.08]; p <.01). Higher age (ß = 0.05 [0.02]; p <.05) and the presence of a retainer (ß = 0.23 [0.07]; p < .05) were associated with calculus accumulation on the lingual side in the mandible. CONCLUSION: The present observational study suggest that long-term fixed retainers alone have no detrimental effect on the periodontium. Additional factors may increase the risk of plaque deposits and increased probing pocket depths. Further prosepective studies are needed to confirm the present outcome.

Craniofacial Growth in Adolescence and its Influence on the Mandibular Incisor Crowding.

BACKGROUND: To analyze craniofacial growth during adolescence from the ages of 12 to 21 years and its relation to late mandibular incisor crowding. MATERIAL AND METHODS: The study included 61 orthodontically untreated subjects (49% males). Lateral cephalograms were used to assess the jaw growth and inclination of the incisors. Little's Irregularity Index and the anterior mandibular dental arch depth of mandibular dentition were measured. RESULTS: A reduction of the skeletal class angle (ANB) was observed in both genders, although it was significant only in males (η2=0.188; p=0.015). The growth of the mandible was more prominent compared to that of the maxilla, and it was more prominent in males than in females. The skeletal vertical dimension, however, demonstrated a significant reduction in both genders (η2=0.527-0.593, p<0.001). The mandibular incisors tended to retrocline in both genders, while the maxillary ones tended to procline in males, and slightly retrocline in females. A decrease in the mandibular dental arch depth occurred in both genders (η2=0.259; p<0.05). An increase in the irregularity of incisors for 1.8±1.7 mm on average (95% CI 1.3-2.2; η2=0.520; p<0.001) was observed in both genders. A logistic regression revealed that less sagittal growth of maxilla (increase of SNA angle ≤2°) and reduction of convexity in skeletal sagittal interjaw relationship (reduction of ANB ≥1°) were significant predictors of the occurrence of crowding (Δ Little Irregularity Index ≥1mm) yielding odds ratios of 4.9 and 4.8. CONCLUSIONS: The differential growth of the maxilla and mandible is related to the occurrence of late crowding, mostly in smaller amounts in maxillary sagittal growth compared to the mandible.

Occlusal outcome after orthodontic treatment with preadjusted straight-wire and standard edgewise appliances : A retrospective cohort study.

PURPOSE: Orthodontic fixed appliances have been proven to be effective in treating a wide variety of malocclusions, and different types of appliances have emerged during recent decades. However, the comparative effects of different appliances have not been adequately assessed. Thus, the aim was to assess the occlusal outcome of orthodontic treatment with preadjusted straight-wire (SWIRE) and standard edgewise (SEDGE) appliances. METHODS: In all, 56 patients (mean age: 13.5 years; 45% male) receiving extraction-based treatment with either SWIRE or SEDGE appliances were included. Between-group differences in the occlusal outcome assessed with the American Board of Orthodontists Objective Grading System (ABO-OGS) and treatment duration were analyzed statistically at the 5% level. RESULTS: The average ABO-OGS score was 31.3 ± 7.2 points and 34.0 ± 10.4 points in the SWIRE and SEDGE groups with no statistically significant difference between groups (P = 0.26). Treatment duration was significantly shorter in the SWIRE group compared to the SEDGE group, with an average difference of -6.8 months (95% confidence interval [95% CI] = -9.6 to -4.0 months; P < 0.001). Likewise, fewer visits were needed with SWIRE compared to SEDGE appliances with an average difference of -7.2 visits (95% CI = -10.3 to -4.2 visits; P < 0.001). Adjusting for the influence of any potential confounders did not considerably impact the results. CONCLUSION: Similar treatment outcomes were observed after premolar extraction treatment with SWIRE and SEDGE appliances. On the other hand, SEDGE appliances were associated with prolonged treatment duration and more visits needed to complete treatment compared to SWIRE appliances.

Stability of single-jaw vs two-jaw surgery following the correction of skeletal class III malocclusion: A systematic review and meta-analysis.

This review aims to compare the stability of sagittal skeletal and overjet anteroposterior correction of skeletal class III malocclusion in single-jaw and two-jaw orthognathic procedures. An unrestricted comprehensive electronic search was undertaken on Embase, Cochrane's CENTRAL, Web of Science, Medline, Scopus and LILACs databases up to October 2020. The bibliographies of relevant studies, ongoing, unpublished and grey literature were screened. Two independent reviewers performed study selection, bias assessment and data extraction; a third reviewer mediated inconsistencies. Randomized clinical trials, prospective cohort, retrospective cohort and series with a minimum of 1 year follow-up were eligible for inclusion. Additional subgroup analyses were undertaken. The generated effects were scored using the GRADE approach. Nine articles met the inclusion criteria and eight studies were subsequently analysed quantitatively. No significant difference in sagittal stability at the ANB angle, A-point or B-point on a short-term was detected. However, a statistically significant difference, indicating a greater short-term relapse in overjet with mandibular setbacks alone, was found (MD: -0.40 mm; 95% CI -0.77 to -0.04; I2 : 0%; P = .03). Long-term follow-up (≥5 years) revealed a statistically non-significant difference in stability of sagittal skeletal and overjet corrections. Within the limitations of this review, both procedures seem to offer comparable skeletal and overjet stability outcomes; however, further high-quality research is required to confirm these findings.

Effectiveness of prefabricated myofunctional appliances in the treatment of Class II division 1 malocclusion: a systematic review.

BACKGROUND: Prefabricated myofunctional appliances (PMAs) are widely advocated for correcting Class II division I malocclusion. However, their effectiveness is associated with a high amount of uncertainty within contemporary literature. OBJECTIVES: The aim of this review was to systematically examine the available literature regarding the effectiveness of PMAs in treating Class II division 1 malocclusion in children and adolescents. SEARCH METHODS: Comprehensive unrestricted electronic searches in multiple databases as well as manual searches were conducted up to August 2018. SELECTION CRITERIA: Randomized controlled trials (RCTs) and non-randomized studies (NRS) matching the eligibility criteria. DATA COLLECTION AND ANALYSIS: Two independent review authors were directly involved in study selection, data extraction, and bias assessment. The Cochrane risk of bias tool and the ROBINS-I tool were used for assessing the risk of bias. Quantitative pooling of the data was undertaken with a random-effects model with its 95% confidence interval (CI). RESULTS: Three RCTs comparing PMAs to activators and three NRS comparing PMAs to untreated controls met the inclusion criteria. On a short-term basis, exploratory quantitative synthesis indicated that the activators were more effective than the PMAs in correcting overjet with a mean difference of (1.1 mm; 95% CI: 0.44 to 1.77). On a long-term basis, there were no significant differences between the two appliances. Qualitative synthesis indicated less favorable soft tissue changes as well as patient experiences and compliance with the PMAs when compared to the activators. However, PMAs were associated with reduced costs compared to customized activators and modest changes when compared to untreated controls. CONCLUSIONS: On a short-term basis, low quality of evidence suggests that PMAs were generally less effective than the activators in treating Class II division 1 malocclusion. The main advantage of PMAs seems to be their reduced costs. These results should be viewed with caution, as a definitive need for high-quality long-term research into this area is required. REGISTRATION: PROSPERO (CRD42018108564).

Irisin promotes growth, migration and matrix formation in human periodontal ligament cells.

OBJECTIVE: The objective of the study was to examine the effect of irisin on human periodontal ligament cells (hPDLCs) growth, migration and osteogenic behaviour in vitro. MATERIALS AND METHODS: Primary hPDLCs and human osteoblasts (hOBs), used as positive controls, were cultured with irisin (10 and 100 ng/ml), and effect on cell proliferation was evaluated with 5-bromo-2`-deoxyuridine incorporation at 1, 2, and 3 days, and on migration capacity was investigated by scratch assay at 2, 6, and 24 h. Osteogenic behaviour was assessed with alkaline phosphatase activity, immunoassay at 3, 7, 14, and 21 days, and confocal laser scanning microscopy at 21 days. Mineralization was examined by Alizarin red staining at 21 days. Data were compared group wise using ANOVA tests. RESULTS: Irisin induced increased proliferation of primary hPDLCs and hOBs at all time points compared to untreated controls. This was confirmed by scratch assay where irisin enhanced migration of both hPDLCs and hOBs after 6 and 24 h compared to controls. Irisin treatment promoted osteogenic behaviour of both cell types by enhancement of extracellular matrix formation. In hPDLCs irisin increased expression of type I collagen, secretion of osteoblastogenesis related proteins osteocalcin and leptin, and calcium deposition/mineralization compared to controls at 21 days. In addition, to enhance calcium deposition/mineralization in hOBs, irisin increased expression of periostin, and secretion of osteoblastogenesis related proteins osteopontin, alkaline phosphatase and osteocalcin, as compared to controls at 21 days. CONCLUSIONS: Primary hPDLCs responded to irisin treatment with enhanced cell growth, migration, and matrix formation in vitro.

Changes of mandibular dental arch shape during adolescence and its influence on late mandibular incisor crowding.

The aim was to analyze the changes in mandibular dental arch shape during adolescence and assess its relation to late mandibular incisor crowding. Longitudinal study included 68 orthodontically untreated subjects (49% female) and analyzed their data for the ages of 12, 15, 18 and 21 years. Measurements included anterior arch depth, intercanine, interpremolar/anterior and intermolar/posterior width, Little's Irregularity and Bolton's index and the ratio between anterior arch depth and width. Males had significantly greater posterior widths than females at any age (p < 0.05). The anterior arch depth continuously decreased (p < 0.05), while width increased after the age of 18 years. Mandibular incisor crowding increased during all investigated periods (p < 0.05). The increase of intercanine width at 12-21 years of age reduced the risk for mandibular incisor crowding in the same period by 74% (OR: 0.265: 95% CI 0.076-0.931; p = 0.045). The shape of mandibular dental arch continues to change during adolescence becoming more squared while mandibular incisor crowding increases. The increase in mandibular intercanine width reduces the risk of crowding.

Occlusal changes during a 10-year posttreatment period and the effect of fixed retention on anterior tooth alignment.

INTRODUCTION: The objectives of this research were to evaluate changes in occlusal components in 3 subperiods during a 10-year posttreatment time span and to examine the long-term effects of fixed retention on maxillary and mandibular anterior alignment. METHODS: Ninety-six patients were examined; the Peer Assessment Rating Index and Little's Irregularity Index were measured at pretreatment, posttreatment, and 3 (T3), 5 (T5), and 10 (T10) years posttreatment. Unweighted Peer Assessment Rating component scores were analyzed for differences between all subperiods. The effect of fixed retention on posttreatment changes in Little's Irregularity Index was analyzed for both jaws with regression analysis. For the maxilla, 2 groups were compared: MX0, removable retainer until T3 (n = 52) and MX10, removable retainer until T3 combined with a fixed retainer until T10 (n = 23). For the mandible, 3 groups were compared: MD3, fixed retainer until T3 (n = 19); MD5, fixed retainer until T5 (n = 19); and MD10 fixed retainer until T10 (n = 48). RESULTS: The Peer Assessment Rating Index percentage of improvement was 79% at T10. A gradual deterioration of occlusal components was seen, with small insignificant changes in each subperiod. Corrected for pretreatment irregularity, MX10 showed 0.6 mm lower LII than MX0. MD10 had significantly better alignment than MD3 (1.1 mm) and MD5 (0.7 mm). CONCLUSIONS: Gradual occlusal changes of limited clinical importance were seen during a 10-year posttreatment period. Long-term fixed retention in the maxilla was of minor importance in patients also wearing removable retainers. In the mandible, a 10-year fixed retention protocol gave moderately lower alignment scores compared to a 3-year protocol and slightly better alignment compared to a 5-year protocol.

The effect of biologic factors and adjunctive therapies on orthodontically induced inflammatory root resorption: a systematic review and meta-analysis.

Objective: Biologic factors and adjunctive therapies are known to affect the degree of orthodontically induced inflammatory root resorption (OIIRR). However, a systematic overall assessment of their impact on OIIRR has not previously been reported. We, therefore, aimed to systematically assess effects on OIIRR of biologic factors and adjunctive therapies in human and animal subjects. Methods: A comprehensive search strategy was performed for all major electronic databases. Two reviewers independently selected studies, undertook data extraction and assessed the risk of bias for all included studies according to a pre-specified protocol inspired by Cochrane and the PRISMA guidelines. Eligible studies compared the effect of intervention(s) in an experimental and a control group. Results: A total of 9 human and 36 animal trials met the inclusion criteria. Where appropriate, random-effect meta-analyses were carried out to determine the outcome measure OIIRR. The random-effect meta-analysis demonstrated that OIIRR was inhibited by fluoride (ES = -2.08 [-3.02, -1.14]), thyroxine (ES = -1.91 [-3.20, -0.61]), and steroids (ES = -2.79 [-4.26, -1.33]). In contrast, corticotomy (ES = 0.38 [0.05, 0.71]) significantly enhanced OIIRR. Conclusion: In animals, administration of fluoride, thyroxine and steroids decreased OIIRR, whereas corticotomy increased OIIRR. In general, the effect on OIIRR increased with higher dosage and/or exposure time. Despite methodological limitations of the included studies, this systematic review provides an important overview of the effect of biologic factors and adjunctive therapies on OIIRR.

Adiponectin prevents orthodontic tooth movement in rats.

OBJECTIVE: The objective was to examine the effects of repetitive local administration of adiponectin on experimental tooth movement in rats. MATERIALS AND METHODS: The maxillary right first molar of male Wistar rats (n=24) was moved mesially for 14days, with local adiponectin injections (0.2 or 2µg) every third day. Micro-computed tomography was performed at days 0, 6 and 14 and molar movement, bone density and bone volume fraction were calculated from the scans. Changes in extracellular matrix collagen and cell numbers in the periodontal ligament were analyzed histologically, and levels of circulating cytokines were measured by Luminex and ELISA. RESULTS: Adiponectin injections induced a reduction in tooth movement after 12 and 14days compared to controls. No tooth movement was observed between days 3 and 14 in the group receiving the highest dosage (2µg) of adiponectin. Differences in bone density and bone volume fractions between treatment and control groups were not identified. Relative size and morphology of collagen fibrils, and cell number in the periodontal region after adiponectin injections were unchanged compared to controls. Levels of circulating adiponectin or other selected factors in plasma were not influenced by the adiponectin injections. CONCLUSIONS: Submucosal injections of adiponectin prevented experimental tooth movement in rats. The effect was dosage-dependent and local. Adiponectin injections caused no detectable changes in bone density, periodontal cell number or collagen content.

Long-term influence of fixed lingual retainers on the development of gingival recession: A retrospective, longitudinal cohort study.

OBJECTIVE: To investigate the long-term influence of fixed lingual retainers on the development of mandibular gingival recession and to compare the prevalence with untreated individuals. MATERIALS AND METHODS: The material consisted of 144 subjects: 96 orthodontically treated patients followed for 5 years after therapy and 48 untreated age-matched subjects. The treated patients were divided in two groups: one receiving a fixed mandibular retainer (n = 48) and one receiving no form of retention in the mandible (n = 48). The presence or absence of gingival recession and calculus accumulation were scored before treatment (T0), after debonding (T1), and 5 years after debonding (T5) for each tooth in the mandibular intercanine region using plaster models and intraoral photographs. The chi-square test, one-way ANOVA, and Cochran's Q test were used to evaluate inter- and intragroup differences. RESULTS: The prevalence of patients with recession increased gradually and significantly throughout the observation periods in all groups, but the intergroup differences at T5 were not significant. Significantly more calculus accumulation was observed at T5 in the retainer group compared with the group without retainers. CONCLUSIONS: Long-term presence of fixed lingual retainers does not seem to increase the development of mandibular gingival recession, but does increase calculus accumulation.