The oral microbiota and periodontal health in orthodontic patients.

The oral microbiota develops within the first 2 years of childhood and becomes distinct from the parents by 4 years-of-age. The oral microbiota plays an important role in the overall health/symbiosis of the individual. Deviations from the state of symbiosis leads to dysbiosis and an increased risk of pathogenicity. Deviations can occur not only from daily life activities but also from orthodontic interventions. Orthodontic appliances are formed from a variety of biomaterials. Once inserted, they serve as a breeding ground for microbial attachment, not only from new surface areas and crevices but also from material physicochemical interactions different than in the symbiotic state. Individuals undergoing orthodontic treatment show, compared with untreated people, qualitative and quantitative differences in activity within the oral microbiota, induced by increased retention of supra- and subgingival microbial plaque throughout the treatment period. These changes are at the root of the main undesirable effects, such as gingivitis, white spot lesions (WSL), and more severe caries lesions. Notably, the oral microbiota profile in the first weeks of orthodontic intervention might be a valuable indicator to predict and identify higher-risk individuals with respect to periodontal health and caries risk within an otherwise healthy population. Antimicrobial coatings have been used to dissuade microbes from adhering to the biomaterial; however, they disrupt the host microbiota, and several bacterial strains have become resistant. Smart biomaterials that can reduce the antimicrobial load preventing microbial adhesion to orthodontic appliances have shown promising results, but their complexity has kept many solutions from reaching the clinic. 3D printing technology provides opportunities for complex chemical syntheses to be performed uniformly, reducing the cost of producing smart biomaterials giving hope that they may reach the clinic in the near future. The purpose of this review is to emphasize the importance of the oral microbiota during orthodontic therapy and to use innovative technologies to better maintain its healthy balance during surgical procedures.

Three-Dimensional Cone Beam Computed Tomography (CBCT)-Derived Soft Tissue Changes in Patients with Unilateral Cleft Lip, Alveolus, and Palate with Midfacial Deficiency after 1.5 Years of Bone-Anchored Maxillary Protraction.

Background: Bone-anchored maxillary protraction (BAMP) aims to correct midfacial deficiencies, with proven positive skeletal changes without potential unwanted side effects. However, the influence of BAMP treatment on facial soft tissues, particularly in subjects with complete unilateral cleft lip, alveolus, and palate (CUCLAP), remains unclear. Methods: This single-center longitudinal cohort study examined the effects of 1.5 years of BAMP treatment on facial soft tissues in growing subjects with complete unilateral cleft lip, alveolus, and palate. The sample consisted of 25 patients, age range 9.7 to 12.6 years. Three-dimensional surface models derived from CBCT scans were superimposed on stable structures of the anterior cranial base and on the occipital area posterior of the foramen magnum to assess three-dimensional changes due to growth and BAMP therapy. Results: The results revealed a moderate positive correlation (Pearson's correlation coefficient from 0.203 to 0.560) between changes in hard tissue and soft tissue; some correlations were found to be weak (<0.300). Linear changes in soft tissue following BAMP were in the same direction as skeletal changes, showing downward, forward, and outward displacement. The only exception was in the vertical dimension. The lower facial third showed a slight but significant reduction, mainly in lip length (-1.2 mm), whereas the middle facial third showed a small increase (1.1 mm). Conclusions: It was concluded that during BAMP, soft tissue changes occur in the same direction as skeletal changes, although with a larger variability and less pronounced effects.

Volumetric changes in the upper airway on CBCT after dentofacial orthopedic interventions - a systematic review.

OBJECTIVE: To provide a critical overview of the effect of various orthodontic and/or dentofacial orthopedic interventions on three-dimensional volumetric changes in the upper airway. MATERIALS AND METHODS: Four databases were searched for clinical studies concerning 3D volumetric assessments based on CBCT before and after orthodontics interventions. The quality of the studies was assessed using the quality assessment tool of the National Heart, Lung and Blood Institute. After the use of inclusion and exclusion criteria, the pre-and post-treatment volumes were used to visualize the effect of various orthodontics interventions. RESULTS: A total of 48 studies were included in this review and none of which were RCTs. The quality of all included studies was assessed as medium. Overall, there is a tendency for an increase in airway volumes after various orthodontic interventions, except for studies concerning extraction therapy with fixed appliances in adults, in which both increases and decreases in airway volumes have been reported. CONCLUSION: Orthodontic treatment by growth modification and non-extraction therapy with fixed appliances, regardless of the malocclusion, generally showed positive effects on the airway volume. Orthodontic treatment in combination with extractions does not provide an unambiguous insight. A consensus on the methodology of the airway measurement and nomenclature is urgently needed in order to gain insight into the effect of different interventions on three-dimensional airway changes. CLINICAL RELEVANCE: Various orthodontic treatments do not negatively influence the upper airway volume. However, extraction therapy in adults should be chosen with caution, especially in subjects belonging to a group susceptible to airway obstruction.

A brief history of orthodontic retention.

The retention phase has become an accepted part of orthodontic therapy. Irrespective of the patient's age, underlying malocclusion or the type of mechanotherapy, an orthodontist will use some retention method in virtually every patient following completion of the active treatment. This article presents a short description of the history of orthodontic retention and highlights major developments in retention strategy.

How do general dental practitioners perceive and deal with orthodontic bonded retainers?

INTRODUCTION: Long-term follow-up and management of orthodontic bonded retainers require a strong collaboration between orthodontists and general dental practitioners (GDPs). This study aimed to evaluate if Eastern French GDPs were aware of bonded retainers' complications and side effects and if they were willing to take part in their long-term follow-up. METHODS: Two-hundred and eighteen randomly selected GDPs were invited to answer an online questionnaire. The initial sections covered their experience and management with bonded retainers. In the final sections, GDPs were asked their opinion on the responsibility for long-term follow-up of patients wearing fixed retainers and on the mutual communication between orthodontists and GDPs. Statistical analysis involved descriptive statistics and Fisher exact tests. RESULTS: Response rate was 32.6% (n = 71). The vast majority of GDPs were familiar with loose retainers, but only 45.2% were willing to repair them. Respondents offering orthodontic services on a regular basis were more likely to insert retainers and repair loose or broken retainers (P < 0.001). Approximately 18.6% of GDPs were aware of third-order side effects encountered with unintentionally active retainers bonded to all 6 anterior teeth. For 88.8% of GDPs, permanent retention was justified, whereas 90% of the dentists refused to be responsible for long-term supervision of fixed retainers. In addition, 67.1% were interested in further training on orthodontic retention, and 92.9% would appreciate clinical guidelines. CONCLUSIONS: Knowledge about the harmful side effects of bonded retainers was evaluated as insufficient among surveyed GDPs. Long-term follow-up of patients wearing bonded retainers raises issues that should be addressed globally by enhancing mutual communication, practitioners' education, and patients' involvement.

Development of a clinical practice guideline for orthodontic retention.

OBJECTIVES: To develop a clinical practice guideline (CPG) for orthodontic retention (OR). MATERIALS AND METHODS: The CPG was developed according to the AGREE II instrument and EBRO (Dutch methodology for evidence-based guideline development). Reporting was done according the RIGHT statement. A Task Force developed clinical questions regarding OR. To answer these questions, a systematic literature search in PubMed and EMBASE was performed. Two independent researchers identified and selected studies, assessed risk of bias using Cochrane RoB tool and rated quality of evidence using GRADE. The Task Force formulated considerations and recommendations after discussing the evidence. The concept CPG was sent for commentary to all relevant stakeholders. RESULT: One systematic review-with 15 studies-met the inclusion criteria. In case of low evidence and lack of outcome measures, expert-based considerations were developed. Over four meetings, the Task Force reached consensus on considerations and recommendations, after which the concept CPG was ready for the commentary phase. After processing the comments, the CPG was presented to the Dutch Association of Orthodontists, whereafter authorization followed. LIMITATIONS: The paucity of evidence-based studies concerning OR and the reporting of measurable patient outcomes. CONCLUSION: This CPG offers practitioner recommendations for best practice regarding OR, may reduce variation between practices and assists with patient aftercare. A carefully chosen retention procedure for individual patients, combined with clear information and communication between orthodontist, dentist and patient will contribute to long-term maintenance of orthodontic treatment results.

Epidemiologic study of orthodontic retention procedures.

INTRODUCTION: The aims of this study were to survey current retention procedures applied by Dutch orthodontists and to examine their acquaintance with "unintentionally active retainers." METHODS: A questionnaire was sent to all 306 Dutch orthodontists involved in patient treatment. Questions were clustered in 4 parts: (1) general information, (2) retention procedures, (3) characteristics of wire materials for bonded retainers, and (4) acquaintance with "unintentionally active retainers." RESULTS: The response rate was 98%. The most applied retention modality in the maxillary arch was a combination of a removable and a bonded retainer (54%); in the mandibular arch, mainly a bonded retainer without a removable retainer was used (83%). Bonded retention was aimed to be lifelong for the maxillary arch (90%) and the mandibular arch (92%). Mean removable retention duration was 2 years. Vacuum-formed retainers were used more frequently and Hawley-type retainers less frequently. The wire materials used for bonded retainers were diverse. All orthodontists were familiar with unintentionally active retainers; 44% believed this phenomenon is caused by the properties of round multistrand wires. The opinion that unwanted changes in tooth position can arise due to the properties of round multistrand wire material was associated with changing the wire material (P <0.005). CONCLUSIONS: Lifelong retention with bonded retainers continues to increase. All orthodontists were acquainted with unintentionally active retainers and their impact. There is a need to identify all causative factors of inadvertent tooth movement in relation to bonded retainers and to prevent the onset of unintentionally active retainers.

Gingival recession in mandibular incisors and symphysis morphology-a retrospective cohort study.

Objective: To evaluate if the morphology of the mandibular symphysis is associated with the development of gingival recession. Materials and methods: A cohort of 177 patients was followed longitudinally for up to 5 years post-treatment. Based on the width of the symphysis, participants were divided into three groups: narrow (n = 57); average (n = 63), and wide symphysis (n = 57). Morphology of the symphysis and inclination of incisors were measured on lateral cephalometric radiographs before treatment (Ts), at the end of treatment (T0) and 5 years after treatment (T5). Gingival recession and the change of clinical crown heights in mandibular incisors were measured on plaster models made at TS, T0, and T5. Results: From TS to T5 the change in inclination was comparable in the narrow, average, and wide groups. At T5, gingival labial recession was present in 19.3 per cent of patients with narrow symphysis, 20.6 per cent with average symphysis, and 14 per cent of patients with wide symphysis. The difference was not significant. The mean change of clinical crown height was <1 mm (TS - T5). The regression model showed some evidence that incisor inclination at Ts might have been associated with the change of mean clinical crown height (-2.51, 95% CI: -4.6 to -0.4, P = 0.02). The logistic regression model demonstrated that H1 (Height 1) might be associated with the development of gingival recession (OR = 0.75, 95% CI: 0.58 to 0.96, P = 0.03). Conclusion: Within the limitations of this study, there is no evidence that the overall morphology of the mandibular symphysis is associated with gingival recession development.

A survey of general dentists regarding orthodontic retention procedures.

AIM: To explore 1. how Swiss general dentists deal with complications associated with fixed orthodontic retainers, 2. collaboration between general dentists and orthodontists with regards to the organization and responsibility for long-term follow-up of orthodontic retainers, and 3. the need for standardized clinical guidelines regarding orthodontic retention. METHODS: A structured questionnaire was sent to 201 randomly selected dentists. They were asked about their experience with retainers, opinions regarding the advantages and disadvantages of different types of retainers, responsibility for patients wearing bonded retention and the communication between orthodontists and general dentists. Statistical analysis was carried out using SPSS software. RESULTS: The response rate was 61 per cent. About 55 per cent of the respondents had had experience with bonding fixed retainers and even more were familiar with their follow-up and repair. In case of complications, dentists usually contacted orthodontists according to the following rule: the more severe the complication, the more intense the communication. Most dentists hesitated to remove retainers when requested to do so by the patient and attempted to convince them to continue wearing them. Retainers bonded to all six anterior teeth were considered more efficient than those bonded to canines only; however, possible side effects (e.g. unwanted changes of the torque) were not well known. 66.4 per cent respondents were willing to take responsibility for patients in retention as early as 6 months after retainer placement. 93.2 per cent respondents would welcome the establishment of standardized guidelines. CONCLUSIONS: Swiss general dentists have good knowledge of orthodontic retention and follow-up procedures. Nevertheless, introduction of clinical guidelines including information on the possible side-effects of bonded retention is justified.

The cervical vertebrae maturation (CVM) method cannot predict craniofacial growth in girls with Class II malocclusion.

INTRODUCTION: The cervical vertebrae maturation (CVM) method is used to determine the timing of treatment of Class II malocclusion. Because its performance has not been tested in patients with Class II, the objective of this study was to evaluate the effectiveness of the CVM method in predicting craniofacial growth in Class II malocclusion. METHODS: Twenty-nine untreated girls with Class II malocclusion were identified among participants of the Nijmegen Growth Study. Each girl had a series of cephalograms taken semi-annually from 9 to 14 years of age. The CVM status was established by five observers on a cephalogram taken at 9 years; mandibular and maxillary length and anterior face height were assessed on all available cephalograms. Method error was evaluated with kappa statistics and Bland-Altman (BA) plots. Regression analysis was used to determine if CVM grade can predict the amount of facial growth. RESULTS: The mean kappa for intra-rater agreement during grading with CVM was 0.36 (fair agreement). BA plots demonstrated acceptable agreement for cephalometric measurements. The regression analysis demonstrated that the only chronologic age was associated with the facial growth. The largest effect of age was for condylion-gnathion (Cd-Gn) and articulare-gnathion (Ar-Gn)-for every additional 6 months the Cd-Gn increases by 1.8mm [95 per cent confidence interval (CI): 1.7, 1.9, P < 0.001] and Ar-Gn increases by 1.59mm (95 per cent CI: 1.52, 1.67, P < 0.001). The CVM grade could not predict the change of cephalometric variables. CONCLUSIONS: There is no evidence to support the hypothesis that the CVM method can predict the amount of craniofacial growth in girls with Class II malocclusion.

No association between gingival labial recession and facial type.

OBJECTIVE: To evaluate if facial type is a predictor of the development of gingival recession. METHODS: A cohort of 179 orthodontic patients (76 males, 101 females; age before treatment T S = 12.4 years, SD = 0.8) were followed until 5 years post-treatment (T 5 = 20.7 years, SD = 1.2). The presence of recessions was scored ('Yes' or 'No') by two raters on initial (T S), end of treatment (T 0), and post-treatment (T 5) plaster models. A recession was noted (scored 'Yes') if the labial cemento-enamel junction was exposed. The clinical crown heights were measured at T S, T 0, and T 5 as the distances between the incisal edges and the deepest points of the curvature of the vestibulo-gingival margins. Determination of the facial type was based on the inclination of mandibular plane relative to cranial base (Sella-Nasion/Mandibular Plane) and the proportion of posterior to anterior face heights (PFHs; SGo/NMe × 100 per cent) on pre-treatment cephalograms. RESULTS: From T 0 to T 5, the number of subjects with recessions increased from 2 (1.1 per cent) to 24 (13.6 per cent), and the number of recession sites increased from 2 to 39. However, most patients had either one or two recession sites. The mean clinical crown height of mandibular incisors increased by 0.86mm (SD = 0.82, P < 0.001). Regression analysis showed that mandibular plane inclination had no effect on the development of gingival recession or on the increase of clinical crown heights of mandibular incisors. CONCLUSIONS: Facial type is not a predictor of the occurrence of gingival recession.

Gingival labial recessions and the post-treatment proclination of mandibular incisors.

INTRODUCTION: A prerequisite for development of gingival recession is the presence of alveolar bone dehiscence. Proclination of mandibular incisors can result in thinning of the alveolus and dehiscence formation. OBJECTIVE: To assess an association between proclination of mandibular incisor and development of gingival recession. METHODS: One hundred and seventeen subjects who met the following inclusion criteria were selected: 1. age 11-14 years at start of orthodontic treatment (TS), 2. bonded retainer placed immediately after treatment (T0), 3. dental casts and lateral cephalograms available pre-treatment (TS), post-treatment (T0), and 5 years post-treatment (T5), and 4. post-treatment (T0) lower incisor inclination (Inc_Incl) <95° or >100.5°. Two groups were formed: non-proclined (N = 57; mean Inc_Incl = 90.8°) and proclined (N = 60; mean Inc_Incl = 105.2°). Clinical crown heights of mandibular incisors and the presence of gingival recession sites in this region were assessed on plaster models. Fisher's exact tests, t-tests, and regression models were computed for analysis of inter-group differences. RESULTS: The mean increase of clinical crown heights (from T0 to T5) of mandibular incisors ranged from 0.75 to 0.83mm in the non-proclined and proclined groups, respectively (P = 0.273). At T5, gingival recession sites were present in 12.3% and 11.7% patients from the non-proclined and proclined groups, respectively. The difference was also not significant (P = 0.851). CONCLUSIONS: The proclination of mandibular incisors did not increase a risk of development of gingival recession during five-year observation in comparison non-proclined teeth.

Orthodontic retention procedures in Switzerland.

OBJECTIVE: To survey retention procedures used in orthodontic practices in Switzerland. MATERIAL AND METHODS: A questionnaire previously developed by Renkema et al. (2009) was sent to 223 Swiss orthodontists. The questionnaire comprised six parts, mainly containing multiple-choice questions. Information as to background education of the individual orthodontist, retention in general, frequency of different types of removable or bonded retainers that were used, retention pro- tocol, and the type and size of the wire used for bonded retainers was assessed. RESULTS: The overall response rate was 65 percent. Most orthodontists placed a bonded retainer in the upper and lower arch, except when the upper arch was expanded during treatment or when extractions were performed in the upper arch, in which case they placed a combination of fixed and removable retainers. Opinions varied with regard to how many hours the removable retainers should be worn and the duration of the retention phase. As far as bonded retainers were concerned, 87 percent of the orthodontists preferred life-long retention. Ninety-three percent of the orthodontists considered that the development of a guide- line on retention procedures would be useful. CONCLUSIONS: The choice of retention procedures is mostly based on orthodontists personal preference. A further research into the long-term effectiveness of individual retention protocols is needed.

Gingival labial recessions in orthodontically treated and untreated individuals: a case - control study.

OBJECTIVES: To evaluate the long-term development of labial gingival recessions during orthodontic treatment and retention phase. MATERIAL AND METHODS: In this retrospective case-control study, the presence of gingival recession was scored (Yes or No) on plaster models of 100 orthodontic patients (cases) and 120 controls at the age of 12 (T12 ), 15 (T15 ), 18 (T18 ), and 21 (T21 ) years. In the treated group, T12 reflected the start of orthodontic treatment and T15 - the end of active treatment and the start of retention phase with bonded retainers. Independent t-tests, Fisher's exact tests and a fitted two-part "hurdle" model were used to identify the effect of orthodontic treatment/retention on recessions. RESULTS: The proportion of subjects with recessions was consistently higher in cases than controls. Overall, the odds ratio for orthodontic patients as compared with controls to have recessions is 4.48 (p < 0.001; 95% CI: 2.61-7.70). CONCLUSIONS: Within the limits of the present research design, orthodontic treatment and/or the retention phase may be risk factors for the development of labial gingival recessions. In orthodontically treated subjects, mandibular incisors seem to be the most vulnerable to the development of gingival recessions.

Development of labial gingival recessions in orthodontically treated patients.

INTRODUCTION: Our aim was to assess the prevalence of gingival recessions in patients before, immediately after, and 2 and 5 years after orthodontic treatment. METHODS: Labial gingival recessions in all teeth were scored (yes or no) by 2 raters on initial, end-of-treatment, and posttreatment (2 and 5 years) plaster models of 302 orthodontic patients (38.7% male; 61.3% female) selected from a posttreatment archive. Their mean ages were 13.6 years (SD, 3.6; range, 9.5-32.7 years) at the initial assessment, 16.2 years (SD, 3.5; range, 11.7-35.1 years) at the end of treatment, 18.6 years (SD, 3.6; range, 13.7-37.2 years) at 2 years posttreatment, and 21.6 (SD, 3.5; range, 16.6-40.2 years) at 5 years posttreatment. A recession was noted (scored "yes") if the labial cementoenamel junction was exposed. All patients had a fixed retainer bonded to either the mandibular canines only (type I) or all 6 mandibular front teeth (type II). RESULTS: There was a continuous increase in gingival recessions after treatment from 7% at end of treatment to 20% at 2 years posttreatment and to 38% at 5 years posttreatment. Patients less than 16 years of age at the end of treatment were less likely to develop recessions than patients more than 16 years at the end of treatment (P = 0.013). The prevalence of recessions was not associated with sex (P = 0.462) or extraction treatment (P = 0.32). The type of fixed retainer did not influence the development of recessions in the mandibular front region (P = 0.231). CONCLUSIONS: The prevalence of gingival recessions steadily increases after orthodontic treatment. The recessions are more prevalent in older than in younger patients. No variable, except for age at the end of treatment, seems to be associated with the development of gingival recessions.

Gingival recessions and the change of inclination of mandibular incisors during orthodontic treatment.

SUMMARY A recent systematic review demonstrated that, overall, orthodontic treatment might result in a small worsening of periodontal status. The aim of this retrospective study was to test the hypothesis that a change of mandibular incisor inclination promotes development of labial gingival recessions. One hundred and seventy-nine subjects who met the following inclusion criteria were selected: age 11-14 years at start of orthodontic treatment (TS), bonded retainer placed immediately after treatment (T0), dental casts and lateral cephalograms available pre-treatment (TS), post-treatment (T0), 2 years post-treatment (T2), and 5 years post-treatment (T5). Depending on the change of lower incisor inclination during treatment (ΔInc_Incl), the sample was divided into three groups: Retro (N = 34; ΔInc_Incl ≤ -1 degree), Stable (N = 22; ΔInc_Incl > -1 degree and ≤1 degree), and Pro (N = 123; ΔInc_Incl > 1 degree). Clinical crown heights of mandibular incisors and the presence of gingival recessions in this region were assessed on plaster models. Fisher's exact tests, one-way analysis of variance, and regression models were used for analysis of inter-group differences. The mean increase of clinical crown heights (T0 to T5) of mandibular incisors ranged from 0.6 to 0.91 mm in the Retro, Stable, and Pro groups, respectively; the difference was not significant (P = 0.534). At T5, gingival recessions were present in 8.8, 4.5, and 16.3 per cent patients from the Retro, Stable, and Pro groups, respectively. The difference was not significant (P = 0.265). The change of lower incisors inclination during treatment did not affect development of labial gingival recessions in this patient group.

Long-term effectiveness of canine-to-canine bonded flexible spiral wire lingual retainers.

INTRODUCTION: The flexible spiral wire (FSW) canine-to-canine lingual retainer bonded to all 6 anterior teeth is a frequently used type of mandibular fixed retainer. This study aimed to assess the long-term effectiveness of FSW canine-to-canine lingual retainers in maintaining the alignment of the mandibular anterior teeth after orthodontic treatment. METHODS: The sample consisted of dental casts of 221 consecutively treated patients (75 girls, 146 boys) from the archives of the Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Center, The Netherlands, who received a FSW canine-to-canine lingual retainer bonded to all 6 anterior teeth after active orthodontic treatment. The casts were studied before treatment (Ts), immediately after treatment (T0), 2 years (T2), and 5 years (T5) posttreatment. RESULTS: The main irregularity index decreased significantly from 5.40 mm (SD, 3.47) at Ts to 0.07 mm (SD, 0.23) at T0. At T5, the alignment of the mandibular anterior teeth was stable in 200 patients (90.5%); in 21 patients (9.5%), a mean increase of 0.81 mm (SD, 0.47) was observed. The increase of irregularity was strongly related to the bonding failures of the retainer. In 6 patients (2.7%), unexpected posttreatment complications (torque differences of the incisors, increased buccal canine inclination) were observed. CONCLUSIONS: The FSW canine-to-canine lingual retainer is very effective in maintaining the alignment of the mandibular anterior region after active orthodontic treatment. However, regular checkups are necessary to determine bonding failures, posttreatment changes, and complications as early as possible.

A survey on orthodontic retention procedures in The Netherlands.

The objective of this study was to survey retention procedures used in orthodontic practices in The Netherlands. A questionnaire was sent to all 279 orthodontists working in The Netherlands. The questionnaire consisted of six parts, mainly containing multiple-choice questions. Information as to background data on the individual orthodontist, retention in general, frequency of different types of removable or bonded retainers that were used, retention protocol, and the type and size of the wire used for bonded retainers was assessed. All statistical analyses were performed using Statistical Package for Social Sciences version 12.0.1. Tests for the relationship between two items were based on the chi-square test. The overall response rate was 91 per cent. Most orthodontists placed a bonded retainer in the upper and lower arch, except when the upper arch was expanded during treatment or when extractions were performed in the upper arch, in which case they placed a removable retainer. Opinions varied with regard to how many hours the removable retainers should be worn and the duration of the retention phase. Contraindications for bonded retainers were given by 96 per cent of the orthodontists, with poor oral hygiene being the most commonly mentioned. As far as bonded retainers were concerned, 84 per cent of the orthodontists preferred permanent retention. Fifty-nine per cent of the orthodontists believed that a practice guideline for retention after orthodontic treatment needs to be developed, which was confirmed by the varied responses in this survey.

Effectiveness of lingual retainers bonded to the canines in preventing mandibular incisor relapse.

INTRODUCTION: A retainer bonded to the lingual surfaces of the mandibular canines (3-3 retainer) is a widely used type of retention. Our aim in this study was to assess the effectiveness of the 3-3 mandibular lingual stainless steel retainer to prevent relapse of the orthodontic treatment in the mandibular anterior region. METHODS: The sample consisted of the dental casts of 235 consecutively treated patients (96 boys, 139 girls) from the archives of the Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Center, The Netherlands, who received a 3-3 mandibular lingual stainless steel retainer at the end of active orthodontic treatment. The casts were studied before treatment (Ts), immediately after treatment (T0), and 2 years (T2), and 5 years (T5) posttreatment. RESULTS: The main irregularity index decreased significantly from 7.2 mm (SD, 4.0) at Ts to 0.3 mm (SD, 0.5) at T0; it increased significantly during the posttreatment period to 0.7 mm (SD, 0.8) at T2 and 0.9 mm (SD, 0.9) at T5. The irregularity index was stable during the 5-year posttreatment period (T0-T5) in 141 patients (60%) and increased by 0.4 mm (SD, 0.7) in 94 patients (40%). The intercanine distance increased 1.3 mm between Ts and T0 and remained stable during the posttreatment period. CONCLUSIONS: The 3-3 mandibular lingual stainless steel retainer (bonded to the canines only) is effective in preventing relapse in the mandibular anterior region in most patients, but a relatively high percentage will experience a small to moderate increase in mandibular incisor irregularity.