Minimally important differences in oral health-related quality of life after fixed orthodontic treatment: a prospective cohort study.

BACKGROUND: The minimally important difference (MID, the smallest difference that patients perceive as beneficial) has been proposed to assess whether study results are clinically meaningful, reducing the shortcoming of P-values-based approaches in the assessment of clinical outcomes. The post-treatment changes and the MID in Oral Health-Related Quality of Life (OHRQoL) among adults undergoing fixed orthodontic treatment were investigated. METHODS: Ninety-two patients (29.1 ±â€…6.3 years old, 18 males and 74 females) were prospectively included. Oral Health Impact Profile (OHIP-14) and United Kingdom Oral Health-related Quality of Life (OHQoL-UK) were used to assess OHRQoL at baseline and post-treatment (50.8 ±â€…15.7 months). Global Transition Rating (GTR) was used to assess oral health/well-being, Peer Assessment Review (PAR), and Index of Complexity, Outcome and Need (ICON) were used to assess occlusion. Wilcoxon signed-rank test was used to assess changes in OHRQoL and occlusion, Kruskal-Wallis one-way ANOVA and Mann-Whitney U-test were used to assess associations between OHRQoL and oral health/well-being or occlusion. MID for OHIP-14 and OHQoL-UK was estimated via anchor-based (PAR, ICON, GTR) and distribution-based approach (effect size, standardized response mean, standard error of measurement). RESULTS: The median OHIP-14 and OHQoL-UK post-treatment scores were significantly changed, indicating improved OHRQoL. Based on the agreement between different methods, the MID of OHIP-14 and OHQoL-UK were at least 15 and 6 scale points, corresponding to a large effect size (1.5-1.7). CONCLUSIONS: Orthodontic treatment had a positive long-term impact on OHRQoL. MID for the OHIP-14 and OHQoL-UK provide guidance to interpreting the impact of orthodontic treatment on the OHRQoL of patients.

Clinical effectiveness of the Eruption Guidance Appliances in treating malocclusion in the mixed dentition: A systematic review and meta-analysis.

AIM: To evaluate the clinical effectiveness of the eruption guidance appliances (EGAs) in treating malocclusion in the early mixed dentition. DESIGN: Electronic databases were comprehensively searched for the eligibility literature of the EGA treatment for a period spanning from the earliest available date in each database up to July 2021. Randomized controlled trials, controlled clinical trials, and prospective and retrospective cohort studies were included in the present review. The quality of clinical trials was assessed according to the Cochrane Collaboration's tools (RoB2.0 and ROBINS-I), whereas cohort studies were based on the Newcastle-Ottawa Scale (NOS). The data were gathered and synthesized with the Stata software (version 12). RESULTS: The screen yielded 436 articles, of which 17 papers were potentially eligible, and 7 articles from 3 studies (1 RCT, 1 CCT, and 1 PCS) were qualified for the final review and analysis. The meta-analysis showed both favorable dentoalveolar and skeletal changes in short term. Both overjet and overbite had a significant decrease after treatment (MD = -2.38 mm, 95% CI: -2.82 to -1.94, p < .001, and MD = -2.43 mm, 95% CI: -3.52 to -1.35, p < .001, respectively), and SNB increased significantly by 0.73 degrees (95% CI: 0.17-1.28, p = .01). After the retention period, however, overbite had a significant increase of 0.88mm, which indicated the occurrence of a relapse (95% CI: 0.60-1.16, p < .001). CONCLUSIONS: According to the existing evidence, the EGA treatment is effectively correcting overjet and overbite in the early mixed dentition in short term; furthermore, high-quality and long-term studies are warranted to determine its long-term effectiveness.

Unilateral Scissor Bite Managed with Prefabricated Functional Appliances in Primary Dentition-A New Interceptive Orthodontic Protocol.

A unilateral scissor bite is a type of severe malocclusion in primary dentition that can influence the development of the mandible and face. The present case report describes an interceptive treatment on a 4-year-old girl with a unilateral scissor bite combined with an anterior crossbite, increased reverse overjet, and overbite on a skeletal Class III base. The patient was treated with a new Prefabricated Functional Appliance (PFA) which was modified from a Frankel-III appliance to induce a mandible to move backwards and relieve an occlusion discrepancy of the dental arch, and a functional dental rehabilitation with resin and myofunctional exercises with a PFA which was modified from an oral screen appliance were performed during the treatment. The total treatment time was 11 months and a satisfactory improvement of occlusion and facial esthetics was achieved. This case report presents a new PFA system and treatment protocol in primary dentition which results in a favorable outcome, and the clinical effectiveness of this appliance system warrants further investigation.

Associations between salivary cytokines and periodontal and microbiological parameters in orthodontic patients.

ABSTRACT: Orthodontic treatment can lead to microbial-induced gingival inflammation and aseptic periodontal inflammations. The aim of this study was to investigate the relationship between salivary pro-inflammatory cytokines levels with gingival health status and oral microbe loads among patients undergoing orthodontic treatment.The present investigation was a cross-sectional study among a sample of 111 consecutive orthodontic patients (mean age 18.4 ±â€Š4.4 years). Clinical examinations were conducted to assess the gingival health status employing the Modified Gingival Index, Gingival Bleeding Index, and Plaque Index. Salivary microbiological assessments of total aerobic and anaerobic bacteria count, streptococci count, and lactobacilli count were undertaken. Saliva immunological assessments included Interleukin-1Beta (IL-1ß) and macrophage migration inhibitory factor (MIF) ELISA assays.The mean ±â€Šstandard deviation of salivary IL-1ß was 83.52 ±â€Š85.62 pg/ml and MIF was 4.12 ±â€Š0.96 ng/ml. Moderate positive correlations were found between salivary IL-1ß levels and total aerobic and anaerobic bacteria count, streptococci count, and lactobacilli count (r = 0.380-0.446, P < .001), and weak positive correlations between salivary MIF levels and total salivary aerobic and anaerobic bacteria counts (r = 0.249-0.306, P < .01) were observed. A positive correlation was found between salivary IL-1ß levels and Bleeding Index (r = 0.216, P < .05).The level of salivary IL-1ß positively correlates with oral bacterial load among orthodontic patients; the relationship between inflammatory cytokines and oral microflora deserved further study.

Changes in the upper airway, hyoid bone and craniofacial morphology between patients treated with headgear activator and Herbst appliance: A retrospective study on lateral cephalometry.

BACKGROUND: The present study compared the treatment changes in the upper airway, hyoid bone position and craniofacial morphology between two groups of children with skeletal class II malocclusion treated with the headgear activator (HGA) and Herbst appliance (Herbst). SETTING AND SAMPLE POPULATION: Orthodontic population from the Faculty of Dentistry of the University of Hong Kong. METHODS: Thirty-four skeletal class II patients treated with the HGA (17 patients, mean age 10.6 ± 1.5 years) and the Herbst (17 patients, mean age 11.0 ± 1.4 years) were matched for sex, age, overjet, skeletal class and mandibular divergence. The patients received lateral cephalometric radiographs (LCRs) at the beginning of treatment (T1 ), after treatment (T2 ) and at follow-up (T3 ). In the HGA group, patients underwent LCRs 7 months before the beginning of treatment (T0 ), which were used as growth reference for intra-group comparison. Paired Student's t tests were used for intra- and inter-group comparisons (α = .05). RESULTS: Treatment changes (T2 -T1 ) did not differ significantly between the groups. However, at follow-up (T3 -T1 ) the Herbst group showed a smaller increase than the HGA group in the vertical position of the hyoid bone relative to the Frankfort plane (P = .013) and mandibular plane (P = .013). CONCLUSIONS: There were no significant differences in the upper airway, hyoid bone position and craniofacial morphology between the groups at the end of treatment. However, the Herbst may provide better long-term control of the vertical position of the hyoid bone than the HGA in children with skeletal class II malocclusion.

Incorrect measurements and misleading conclusions in the article "Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study".

BACKGROUND/OBJECTIVE: To reproduce the methods and results of the study by Alobeid et al. (2018) in which the efficacy of tooth alignment using conventional labial and lingual orthodontic bracket systems was assessed. MATERIALS/METHODS: We used the identical experimental protocol and tested (i) regular twin bracket (GAC-Twin [Dentsply]) and lingual twin bracket systems (Incognito [3M]), (ii) together with NiTi 0.014" wires (RMO), and (iii) a simulated malocclusion with a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially). RESULTS: The method described by Alobeid et al. (2018) is not reproducible, and cannot be used to assess the efficacy of tooth alignment in labial or lingual orthodontic treatment. Major flaws concern the anteroposterior return of the Thermaloy-NiTi wire ligated with stainless steel ligatures. The reproduced experimental setting showed that a deflected Thermaloy-NiTi wire DOES NOT move back at all to its initial stage (= 0 per cent correction) because of friction and binding (see supplemented video), neither with the tested labial nor with the lingual brackets. Furthermore, an overcorrection of up to 138 per cent, which the authors indicate for some labial bracket-wire combinations and which deserves the characterization "irreal", stresses the inappropriateness of the method of measurement.Further flaws include: a) incorrect interpretation of the measurement results, where a tooth tripping around (overcorrection) is interpreted as a better outcome than a perfect 100 per cent correction; b) using a statistical test in an inappropriate and misleading way; c) uncritical copying of text passages from older publications to describe the method, which do not correspond to this experimental protocol and lead to calculation errors; d) wrong citations; e)differences in table and bar graph values of the same variable; f) using a lingual mushroom shaped 0.013" Thermaloy-NiTi wire which does not exist; g) drawing uncritical conclusions of so called "clinical relevance" from a very limited in vitro testing. CONCLUSIONS: Clinical recommendations based on in vitro measurements using the Orthodontic Measurement and Simulation System (OMSS) should be read with caution.

Upper Airway Changes following Functional Treatment with the Headgear Herbst or Headgear Twin Block Appliance Assessed on Lateral Cephalograms and Magnetic Resonance Imaging.

OBJECTIVE: The present study compared the changes in the upper airway dimensions and sleep-related breathing disorder (SRBD) condition between functional treatment with the headgear Herbst (HG-Herbst) and headgear Twin Block (HG-TB) appliance. Soft tissues were assessed on lateral cephalometric X-ray and magnetic resonance imaging (MRI). MATERIALS AND METHODS: Consecutive patients who sought orthodontic treatment at the Faculty of Dentistry of The University of Hong Kong were screened. Adolescents (12-17 year sold for boys and 10-15 years old for girls), with class II molar relationship and overjet >5 mm, with no severe transverse maxillary deficiency, were recruited. Patients were assigned either to the HG-Herbst or to the HG-TB treatment by stratified block randomisation, with sex as the stratification factor. Lateral cephalograms, magnetic resonance imaging (MRI), and the Paediatric Sleep Questionnaire (PSQ) were obtained at baseline and after treatment. RESULTS: 28 patients were enrolled, and 26 patients (13 in each group) completed the treatment. Following 1 year of functional appliance treatment, a significantly lower increase of the lower anterior facial height was observed in the HG-Herbst group compared to the HG-TB group (p = 0.024). However, no significant differences were observed in the upper airway structures or SRBD between the two groups. CONCLUSION: The changes in upper airway dimensions and SRBD condition were not significantly different between the HG-Herbst and the HG-TB appliance treatment. Additional studies with larger sample size are warranted.

Orthodontic Treatment Need and the Psychosocial Impact of Malocclusion in 12-Year-Old Hong Kong Children.

OBJECTIVES: To determine the prevalence of orthodontic treatment need in 12-year-old children in Hong Kong and its relationship with the psychosocial impact of malocclusion and to assess their associations with sociodemographic factors. MATERIALS AND METHODS: A random sample of 687 12-year-old children was recruited from 45 secondary schools in Hong Kong. Orthodontic treatment need was assessed on study models by five indices: the Dental Health Component of the Index of Orthodontic Treatment Need (IOTN-DHC), the Aesthetic Component of the IOTN (IOTN-AC), the Dental Aesthetic Index (DAI), the Index of Complexity Outcome and Need (ICON), and the Peer Assessment Rating (PAR). The psychosocial impact of malocclusion on participants and sociodemographic factors were obtained from a questionnaire. Logistic regression was used to examine the correlations between treatment need and the psychosocial impact of malocclusion as well as their associations with sociodemographic factors. RESULTS: The final number of participants was 667 (339 boys and 328 girls, participation rate 667/687 = 97.1%). The prevalence of orthodontic treatment need varied depending on the indices used (10.9-47.8%), but significant correlations were found among the five indices (p < 0.01). The uptake of treatment among the cohort was 2.3%. Boys had higher IOTN-DHC (p < 0.05), DAI (p < 0.05), and PAR (p = 0.05) scores than girls. IOTN-AC was significantly associated with the psychosocial impact of malocclusion (p < 0.05). Parents' level of education and household income were not significantly associated with either treatment need or the psychosocial impact of malocclusion (p > 0.05). CONCLUSION: The need for orthodontic treatment in 12-year-old children in Hong Kong remained high, and the uptake of treatment was low. Boys had a higher normative treatment need than girls. Among the five indices, IOTN-AC appears to be the best indicator of the psychosocial impact of malocclusion.

Elastodontic appliance assisted fixed appliance treatment: A new two-phase protocol for extraction cases.

Elastodontic appliance (EA) is a type of removable appliance that has been widely used in interceptive orthodontics. The present case report describes a severe crowding case treated with a new two-phase protocol by using an EA and a fixed appliance. A 13-year-old patient with severe dental crowding, increased overjet and overbite on a skeletal Class II base was selected. The patient had four bicuspids extracted; during the first phase of treatment, she wore the EA for 2 h during the daytime plus overnight, combined with a myofunctional exercise. During the second phase of treatment, a fixed appliance was employed to close residual space and improve the teeth angulations. The total treatment time was 14 months, of which the second phase with fixed appliance lasted 10 months. Satisfactory improvements of the overjet and teeth alignment were achieved. This case report used a new two-phase treatment protocol which resulted in a favourable outcome after comparatively short treatment.

Digital Models as an Alternative to Plaster Casts in Assessment of Orthodontic Treatment Outcomes.

OBJECTIVE: This study aimed to compare the use of digital models and plaster casts in assessing the improvement in occlusion following orthodontic treatment. MATERIALS AND METHODS: Digital models and plaster casts of 39 consecutive patients at pre- and posttreatment stages were obtained and assessed using the Peer Assessment Rating (PAR) index and the Index of Complexity and Treatment Need (ICON). PAR and ICON scores were compared at individual and group levels. Categorization of improvement level was compared using Kappa (κ) statistics. RESULTS: There was no significant difference in neither PAR scores (p > 0.05) nor ICON scores (p > 0.05) between digital and plaster cast assessments. The Intraclass Correlation Coefficient (ICC) values for changes in PAR and ICON scores were excellent (ICC > 0.80). Agreement of ratings of occlusal improvement level between digital and plaster model assessments was 0.83 (κ) for PAR and 0.59 (κ) for ICON, respectively. CONCLUSION: The study supported the use of digital models as an alternative to plaster casts when assessing changes in occlusion at the 'individual patient' level using ICON or PAR. However, it could not fully support digital models as an alternate to plaster casts at 'the group level' (as in the case of clinical audit/research).

Change of mandibular position during two-phase orthodontic treatment of skeletal class II in the Chinese population.

The aim of this study was to evaluate the change in mandibular position during a two-phase orthodontic treatment of skeletal Class II malocclusion. Thirty consecutively treated Chinese male adolescents who had undergone two-phase treatment with Herbst appliance and fixed appliance and fulfilled the specific selection criteria were sampled. Cephalograms taken at T0 (before treatment), T1 (at the end of functional appliance treatment), and T2 (at the end of fixed appliance treatment) were analyzed. The change in sagittal positioning of the mandible was 6.8 ± 3.44 mm in phase I (T0-T1), 0.4 ± 2.79 mm in phase II (T1-T2), and 7.2 ± 4.61 mm in total. The mandible came forward in 100% of the patients at T1. In phase II, it came forward in one-third (positive group) remained unchanged in one-third (stable group) and went backward in one-third (negative group) of the patients. At T2, it came forward twice as much in the positive group compared to the negative group. Mandibular length was significantly increased in 100% of the patients in both phases. In conclusion, during the treatment with functional appliance, the mandibular prognathism increases in all patients, whereas during the treatment with fixed appliance there is no significant change in mandibular prognathism.

Craniofacial characteristics related to daytime sleepiness screened by the paediatric daytime sleepiness scale.

The present cross-sectional study aimed to assess daytime sleepiness in Chinese adolescents using the Paediatric Daytime Sleepiness Scale (PDSS) and to identify associations between PDSS answers and craniofacial characteristics. A group of 265 Chinese adolescents aged 11-17 years self-completed the PDSS, and their extra- and intra-oral craniofacial characteristics were recorded. Among the participants, 59.7% (157) experienced one or more daytime sleepiness events. No significant associations were found between total PDSS scores and the craniofacial parameters, but when PDSS answers were assessed at the item level, several craniofacial characteristics were found to be positively associated with daytime sleepiness, such as hypertrophic tonsils (P = 0.05), a relatively large tongue (P < 0.01), a bilateral Class II molar relationship (P < 0.05) and increased overjet (P < 0.05). A short lower face (P < 0.01) and a convex profile (P < 0.01) were found to be negatively associated with daytime sleepiness. Daytime sleepiness is commonly reported among Chinese adolescents seeking orthodontic treatment and there are potential associations between the condition and craniofacial characteristics. An assessment of daytime sleepiness is recommended to orthodontists in young patients presenting with hypertrophic tonsils, relative large tongues and Class II tendency malocclusions, and appropriate medical referrals should also be considered.

An evaluation of two different mandibular advancement devices on craniofacial characteristics and upper airway dimensions of Chinese adult obstructive sleep apnea patients.

OBJECTIVES: To evaluate the effects of two different mandibular advancement devices (MADs) on craniofacial characteristics and upper airway dimensions of Chinese adult patients with obstructive sleep apnea (OSA). MATERIALS AND METHODS: Forty-five patients with OSA were recruited as part of a prospective randomized crossover trial for treatment with two different MADs. Lateral cephalograms were taken, and the Epworth Sleepiness Scale and the Sleep Apnea Quality of Life Index were completed at baseline. RESULTS: The Apnea-Hypoxia Index was highly significantly reduced with the monoblock (P < .001) and significantly reduced with the twin block (P < .01). The monoblock demonstrated a superior result than the twin block (P < .05). A significant reduction was found in the distances between the hyoid bone to retrognathia (monoblock, P < .01; twin block, P < .001) as well as the distance between the hyoid bone and mandibular plane angle (P < .001). Furthermore, soft palate length increased significantly (P < .05) with both MADs. However, the changes did not differ in favor of either MAD. CONCLUSION: Monoblock was the better MAD to improve OSA severity. No difference could be found in changes of subjective OSA indicators. Significant but similar cephalometric changes were observed, indicating both MADs alter the position of the surrounding musculature and improve upper airway patency. Therefore, the different design features of the MADs suggest an impact on some OSA indicators.

Angular photogrammetric analysis of the soft tissue profile in 12-year-old southern Chinese.

INTRODUCTION: To quantify average angular measurements that define the soft tissue profiles of 12-year-old southern Chinese and to determine gender differences. MATERIALS AND METHODS: A random population sample of 514 12-year-old children was recruited (about 10% of a Hong Kong Chinese birth cohort). Photographs were taken in natural head posture and 12 soft tissue landmarks were located on the photos to measure 12 angular measurements using ImageJ (V1.45s) for Windows. Approximately 10% of photographs were reanalyzed and method error was calculated. Angular norm values for the 12 parameters were determined and gender differences were assessed using 2 sample T-test with 95% confidence interval. RESULTS: The response rate was 54.1% (278/514). Norm values for the 12 angular measurements were generated. The greatest variability was found for the nasolabial (Cm-Sn-Ls) and labiomental (Li-Sm-Pg) angles. Gender differences were found in 4 angular parameters: vertical nasal angle (N-Prn/TV) (p < 0.05), cervicomental angle (G-Pg/C-Me) (p < 0.001), facial convexity angle (G-Sn-Pg) (p < 0.01) and total facial convexity angle (G-Prn-Pg)(p < 0.01). CONCLUSION: Norm values for 12 angular measurements among 12-year-old southern Chinese children were provided and some variability noted. Gender differences were apparent in several angular measurements. This study has implications in developing norm values for southern Chinese and for comparison with other ethnic groups.

Cephalometric norms for the upper airway of 12-year-old Chinese children.

OBJECTIVE: To establish cephalometric norms for the upper airway of 12-year-old Chinese children, and to assess these norms with regard to gender, age, ethnicity and other craniofacial structures. METHODS: Lateral cephalograms were obtained from a random sample of 425 12-year-old Chinese children (224 boys and 201 girls) to establish the Chinese norms, and from a matched group of 108 12-year-old Caucasian children (61 boys and 47 girls) as an ethnic comparison. Published data on the upper airway norms of Chinese adults were used to make age comparisons. Nine upper airway and 14 craniofacial variables were measured. RESULTS: Chinese boys tended to have a thicker soft palate (P = 0.008), and less depth in the retropalatal (P = 0.011), retroglossal (P = 0.034) and hypopharyngeal (P < 0.001) pharynx than Chinese girls, whereas no gender dimorphism was found in Caucasian children. Ethnic differences were found in the depth of the retroglossal oropharynx in both genders and the position of the hyoid bone in boys. Compared with Chinese adults, the overall size of the upper airway in Chinese children was smaller. The mandibular body length and the craniocervical inclination were found to be statistically significantly, albeit weakly correlated with upper airway variables. CONCLUSIONS: Cephalometric norms for the upper airway of Chinese 12-year-old children were established, indicating gender-specific differences, and some ethnic differences were found in comparison with those of 12-year-old Caucasian children. An association between the mandibular body length and the craniocervical inclination with upper airway variables was also noticeable.

Acid etching of human enamel in clinical applications: a systematic review.

STATEMENT OF PROBLEM: The laboratory-based enamel acid-etching doctrine with 30% to 50% phosphoric acid for 60 seconds to generate the maximum amount of Type 1 and/or Type 2 etch pattern has been established for more than 30 years. However, this recommendation may not be clinically relevant. PURPOSE: The purpose of this systematic review was to compare clinically accepted protocols of enamel acid etching with the laboratory protocol. MATERIAL AND METHODS: Studies were identified by searching 4 electronic databases: Medline, CINAHL Plus, Embase, and Cochrane Library. The final search was run on November 8, 2012. All clinical studies published in English that investigated enamel acid pretreatment methods on human permanent teeth were included. Additional publications were obtained from the reference lists of the included studies. The clinical evidence of all included studies was tabulated. RESULTS: Initially, 4543 publications were retrieved from the databases. A total of 4508 articles were excluded, including 2285 duplicates, 1805 publications according to exclusion criteria by their titles and abstracts, 368 laboratory articles, 49 reviews, and 1 pilot study. Only 1 study was added from reference lists of the included studies. Finally, 36 clinical publications were included. The included clinical studies provided different levels of clinical evidence on the efficacy of acid-etching protocols to enable successful enamel adhesion. CONCLUSIONS: Clinical protocols of enamel acid etching differ from the laboratory-generated doctrine, which may imply that maximization of the Type 1 and/or Type 2 etch pattern is not important in the clinical acid etching of human enamel.

Natural compounds containing mouthrinses in the management of dental plaque and gingivitis: a systematic review.

OBJECTIVES: To evaluate the effectiveness of natural compounds containing mouthrinse (NCCM) as an adjunct to unsupervised oral hygiene in the management of dental plaque and gingivitis. MATERIALS AND METHODS: An electronic search for clinical studies of NCCMs was conducted in Medline-PubMed, the Cochrane Central Register of Controlled Trials and EMBASE for a period spanning from the earliest available date in each database up to February 2013. Plaque index, gingival index, and gingival bleeding index were selected as primary outcomes. The methodological quality of the studies was assessed according to the "Levels of Evidence" outlined by the Center of Evidence-Based Medicine, and to the Jadad scale. RESULTS: The screen yielded 2,236 titles and abstracts that met the inclusion criteria. These identified 11 clinical trials testing 13 different NCCMs, and were used for data extraction. Heterogeneity and the limited number of studies on any individual NCCM precluded a formal meta-analysis. Of the 13 NCCMs tested, eight demonstrated positive results, and few reported any adverse effects or events. CONCLUSIONS: Evidence proving the effectiveness of NCCM as an adjunct to unsupervised oral hygiene for plaque and gingivitis control is still insufficient. However, some natural products (compounds) may have oral health benefits, so further high-quality study is warranted. CLINICAL RELEVANCE: This review provides an overview of the strength of clinical evidence regarding the effectiveness of natural compounds containing mouthrinses in promoting gingival health.

Lingual retainers bonded without liquid resin: a 5-year follow-up study.

INTRODUCTION: The aim of this in-vivo study study was to evaluate the effect of excluding the liquid resin component of a composite bonding product that is based on bisphenol A diglycidylmethacrylate when bonding lingual retainers. METHODS: The material comprised 40 metal multistrand lingual retainers bonded onto the lingual surfaces of maxillary and mandibular anterior teeth. Transbond LR composite paste and liquid resin (3M Unitek, Monrovia, Calif) were used to bond retainers in the control group (20 retainers). The same bonding material was used in the test group (20 retainers), but the liquid resin component was excluded. The durations (in months) of retainer survival were analyzed by using the Kaplan-Meier product limit method and the log rank test. RESULTS: Fifty percent of the retainers in the control group and 60% of those in the test group had no bond failures during the 5-year observation period; the difference was not statistically significant. Bond failures were recorded in 13.6% of the bonded tooth surfaces in the control group and in 14.9% in the test group; the difference was not statistically significant. On average, the retainers stayed intact in the control and test groups for 36 and 32 months, respectively. The median survival times of the control and test groups were 43 months and more than 47 months, respectively. Neither the survival analysis nor the 95% confidence intervals (24-49 months in the control group, 24-40 months in the test group) suggested any statistically significant difference between the groups. CONCLUSIONS: Metal lingual retainers can be successfully bonded without liquid resin and serve the patient equally as well clinically as retainers bonded with the conventional bonding technique.