Tensile forces in the neurovascular bundle: A contributor to orthodontic relapse?

OBJECTIVES: The aim of this study is to investigate the neurovascular bundle (NVB) as a potential orthodontic relapse factor. The mechanical properties and the forces generated in the NVB after orthodontic extrusion are explored. MATERIALS AND METHODS: Six NVBs branching from the inferior alveolar nerve to the apices of the mandibular canines and premolars of mature pigs were harvested. Stress relaxation tests were conducted. A standard linear solid model (SLS) was utilized to simulate the orthodontic extrusion of a single rooted tooth with NVB length and cross-sectional diameter of 3.6 and 0.5 mm, respectively, so the NVB was stretched 10% and 20% of its original length. The maximum force within the NVB was then calculated. RESULTS: Based on our data, the average Young's modulus before relaxation ( E 0 ), after relaxation ( E P ) and the difference between Young's moduli before and after relaxation ( E S ) were 324 ± 123, 173 ± 73 and 151 ± 52 kPa, respectively. The theoretical force within the NVB stretched to 10% and 20% strain was 3 and 5 mN, respectively. CONCLUSION: The data from our study indicate that the NVB exhibits stress relaxation, a characteristic trait of viscoelastic materials. SLS model simulation predicted residual forces around 5 mN for elongation up to 20%. We observed strain hardening with additional elongation, which has the potential to cause forces to increase exponentially. Therefore, tensile forces in the NVB should not be ruled out as a contributor to orthodontic relapse, especially in adult patients who may have decreased adaptability of their NVB. Further preclinical and clinical models should be developed to further clarify what is the contribution of the NVB to orthodontic relapse.

Treatment acceptance in adult patients with anterior open bite: A National Dental Practice-Based Research Network study.

INTRODUCTION: Orthodontists have many techniques to treat anterior open bites and must involve patients in making treatment decisions. This study aimed to investigate orthodontic treatment plan acceptance by United States adults with anterior open bites and to identify associations between treatment acceptance and patient demographics and dentofacial characteristics. METHODS: A prospective, observational cohort study enrolled the patients of 91 orthodontic providers. A total of 345 adults were included in the sample. Provider personal and practice demographics were captured. Patient demographics, treatment goals, dentofacial characteristics, and reasons for not accepting the recommended plans were recorded. Adjusted regression models were used to identify associations between patient characteristics and the likelihood of accepting the most highly recommended plan. RESULTS: Approximately 78% of patients accepted the most highly recommended treatment plan. 60% of the patients who were recommended surgical plans accepted them. Patients with a history of orthodontics and a concave profile were more likely to accept the most highly recommended plan. Insurance coverage for orthognathic surgery was associated with a higher acceptance rate for surgery. Severe crowding was associated with a lower acceptance of surgery. The most common reasons for declining the recommended plan were not wanting jaw surgery and considering the treatment to be too invasive, risky, and/or costly. CONCLUSIONS: Patient acceptance is less common at higher levels of invasiveness of treatment. Prior orthodontic treatment, concave profile, and insurance coverage for surgery were associated with accepting treatment. Most patients accepted a surgical plan when it was the most recommended option.

The National Dental Practice-Based Research Network Adult Anterior Open Bite Study: Patient satisfaction with treatment.

INTRODUCTION: This article evaluates and reports on the satisfaction of adult patients across the United States who received orthodontic treatment for anterior open bite malocclusion. The factors that influence satisfaction are also described. METHODS: Practitioners were recruited from the National Dental Practice-Based Research Network. On joining the Network, practitioner demographics and information on their practices were acquired. Practitioners enrolled their adult patients in active treatment for anterior open bite. Patient demographics, patient dentofacial characteristics, and details regarding previous and current treatment were collected through questionnaires at enrollment (T1). Pretreatment lateral cephalograms and intraoral frontal photographs were submitted. Treatment performed, and details related to treatment outcome were recorded through questionnaires at the end of active treatment (T2). Posttreatment lateral cephalograms and intraoral frontal photographs were submitted. Patient satisfaction at T2 was assessed using a 5-point Likert-type scale and open-ended responses. Predictive univariate models were developed to evaluate the factors that affect patient satisfaction. Open-ended responses were reviewed for general trends. RESULTS: T2 data were received for 260 patients, and 248 of these patients completed and returned the patient satisfaction questionnaires. High levels of satisfaction were found in this sample of adult patients receiving treatment for anterior open bite malocclusion. Specifically, 96% of the sample reported being very or somewhat satisfied. Only 10 patients (4%) were not satisfied with the treatment provided or an element of the final result. Successful open bite closure, treatment modality, and certain patient characteristics may affect patient satisfaction. However, there was insufficient power to demonstrate statistical significance because of the very low number of dissatisfied patients. Open-ended responses directly associated with patient satisfaction were received from 23 patients (9%). They relayed positive, neutral, and negative feelings about the treatment received and final results. Additional responses regarding the orthodontic treatment in general, but not specifically linked to patient satisfaction, were received from 119 patients (48%). These comments depict an overwhelmingly positive experience. CONCLUSIONS: Adult patients who received orthodontic treatment for anterior open bite malocclusion were generally satisfied with the treatment provided, as well as the final esthetic and functional results.

The National Dental Practice-Based Research Network Adult Anterior Open Bite Study: Treatment success.

INTRODUCTION: Anterior open bite (AOB) continues to be a challenging malocclusion for orthodontists to treat and retain long-term. There is no consensus on which treatment modality is most successful. This study reports on the overall success rate of AOB orthodontic treatment in the adult population across the United States, as well as 4 major treatment modalities and other factors that may influence treatment success. METHODS: Practitioners and their adult patients with AOB were recruited through the National Dental Practice-Based Research Network. Patient dentofacial and demographic characteristics, practitioner demographic and practice characteristics, and factors relating to orthodontic treatment were reported. Treatment success was determined from posttreatment (T2) lateral cephalometric films and intraoral frontal photographs. Treatment was categorized into 4 main groups: aligners, fixed appliances, temporary anchorage devices (TADs), and orthognathic surgery. Extractions were also evaluated. Bivariate and multivariable models were used to investigate the association between treatment success and treatment modality, pretreatment (T1) dentofacial characteristics, patient and practitioner demographics, and practice characteristics, adjusting for clustering of patients within practice. RESULTS: A total of 254 patients, enrolled by 84 practitioners, contributed to T2 data for this study. There were 29 patients in the aligner group, 152 in fixed appliances, 20 in TADs, and 53 in surgery. A total of 49 patients underwent extractions of teeth other than third molars. Ninety-three percent finished treatment with a positive overbite on the T2 lateral cephalogram, and 84% finished with a positive vertical overlap of all incisors. The small number of aligners and TAD patients limited the ability to compare success rates in these groups. Patients treated with orthognathic surgery had a higher rate of success compared with those treated with fixed appliances only. Treatment success was also associated with academic practice setting, T1 mandibular plane angle ≤30°, no to mild T1 crowding, and treatment duration <30 months. CONCLUSIONS: The overall success of orthodontic treatment in adult patients with AOB who participated in this study was very high. Orthognathic surgery was the only treatment modality that exhibited a statistically higher odds of successful outcomes. Some T1 dentofacial characteristics and treatment factors were associated with the successful closure of AOB.

Agreement of treatment recommendations based on digital vs plaster dental models.

INTRODUCTION: The purpose of this study was to investigate differences in orthodontists' treatment plans based on digital models compared with plaster models. Additionally, we assessed whether digital or plaster models influence the reliability of orthodontists' treatment plans, as well as the amount of time required to arrive at the plan. METHODS: Sixteen orthodontists planned treatment for 20 patients at 2 time points using either the same or different model formats (digital or plaster). The treatment plan decisions and time spent making the plans were recorded. The permutation test and a random effects model were used to analyze the data. RESULTS: The treatment plans arrived at with digital and plaster models were similar. With respect to extractions, the mean difference between digital and plaster formats was 11.9% (95% CI, 7.5%-16.3%). For surgery, the mean difference was 9.4% (95% CI, 5.0%-13.8%). There was no significant difference in the agreement rate between those who viewed models in different formats compared with those who viewed models twice in the same format (P >0.05). The time spent to plan treatment with plaster models was not significantly different from the time spent with digital models (P = 0.87). CONCLUSIONS: Based on this study, digital models can be substituted for plaster models with no significant differences in the final plans, the reliability of the plans, and the time required to create the plan.

Predicting improvement of postorthodontic white spot lesions.

INTRODUCTION: Patients undergoing orthodontic treatment are at greater risk for developing white spot lesions (WSLs). Although prevention is always the goal, WSLs continue to be a common sequela. For this reason, understanding the patterns of WSL improvement, if any, has great importance. Previous studies have shown that some lesions exhibit significant improvement, whereas others have limited or no improvement. Our aim was to identify specific patient-related and tooth-related factors that are most predictive of improvement with treatment. METHODS: Patients aged 12 to 20 years with at least 1 WSL that developed during orthodontic treatment were recruited from private dental and orthodontic offices. They had their fixed appliances removed 2 months or less before enrollment. Photographs were taken at enrollment and 8 weeks later. Paired photographs of the maxillary incisors, taken at each time point, were blindly assessed for changes in surface area and appearance at the individual tooth level using visual inspection. RESULTS: One hundred one subjects were included in this study. Patient age, brushing frequency, and greater percentage of surface area affected were associated with increased improvement. Central incisors exhibited greater improvements than lateral incisors. Longer time since appliance removal and longer length of orthodontic treatment were associated with decreased levels of improvement. Sex, oral hygiene status, retainer type, location of the lesion (gingival, middle, incisal), staining, and lesion diffuseness were not found to be predictive of improvement. CONCLUSIONS: Of the various patient-related and tooth-related factors examined, age, time since appliance removal, length of orthodontic treatment, tooth type (central or lateral incisor), WSL surface area, and brushing frequency had significant associations with WSL improvement.

Retrospective investigation of the effects and efficiency of self-ligating and conventional brackets.

INTRODUCTION: The purpose of this retrospective cohort study was to assess the effects and efficiency of self-ligating brackets compared with conventional brackets. A secondary purpose was to identify the pretreatment factors associated with the choice of self-ligating or conventional brackets. METHODS: The subjects were treated by 2 private practitioners who used both self-ligating and conventional brackets in their practices. The self-ligating subjects were consecutively identified (treatment completed between January 2011 and April 2012), and then an age- and sex-matched control group was chosen from the same office. The outcome measures were changes in arch dimensions, changes in mandibular incisor inclinations, final peer assessment rating (PAR) scores, percentages of PAR reduction, overall treatment times, total number of visits, and number of emergency visits. All cast and cephalometric measurements were performed on digital records in a blinded manner. Two calibrated assessors measured the PAR scores. RESULTS: The final sample comprised 74 patients from clinician 1 and 34 patients from clinician 2. The practitioners had significant differences for several treatment parameters; therefore, the data from the 2 clinicians were analyzed separately. For clinician 1, no significant differences were observed between the self-ligating and conventional groups, other than increased arch length in the self-ligating group. The self-ligation patients treated by clinician 2 demonstrated significant increases in transverse dimensions, lower percentages of reduction in PAR scores, shorter treatment times, fewer visits, and more wire-sliding emergencies than the conventional bracket group. CONCLUSIONS: Although some significant findings were observed, the small sample and the lack of consistent findings between the 2 clinicians made it difficult to draw strong conclusions.

Recommendations for third molar removal: a practice-based cohort study.

OBJECTIVES: We investigated general dentists' reasons for recommending removal or retention of third molars and whether patients adhered to dentists' recommendations. METHODS: In a 2-year prospective cohort study (2009-2011) in the Pacific Northwest, we followed 801 patients aged 16 to 22 years from 50 general dental practices. Generalized estimating equations logistic regressions related patient and dentist characteristics to dentists' recommendations to remove third molars and to patient adherence. RESULTS: General dentists recommended removal of 1683 third molars from 469 (59%) participants, mainly to prevent future problems (79%) or because a third molar had an unfavorable orientation or was unlikely to erupt (57%). Dentists recommended retention and monitoring of 1244 third molars from 366 (46%) participants, because it was too early to decide (73%), eruption path was favorable (39%), or space for eruption was sufficient (26%). When dentists recommended removal, 55% of participants adhered to this recommendation during follow-up, and the main reason was availability of insurance (88%). CONCLUSIONS: General dentists frequently recommended removal of third molars for reasons not related to symptoms or pathology, but rather to prevent future problems.

A prospective study of clinical outcomes related to third molar removal or retention.

OBJECTIVES: We investigated outcomes of third molar removal or retention in adolescents and young adults. METHODS: We recruited patients aged 16 to 22 years from a dental practice-based research network in the Pacific Northwest from May 2009 through September 2010 who had at least 1 third molar present and had never undergone third molar removal. Data were acquired via questionnaire and clinical examination at baseline, periodic online questionnaires, and clinical examination at 24 months. RESULTS: A total of 801 patients participated. Among patients undergoing third molar removal, rates of paresthesia and jaw joint symptoms lasting more than 1 month were 6.3 and 34.3 per 100 person-years, respectively. Among patients not undergoing removal, corresponding rates were 0.7 and 8.8. Periodontal attachment loss at distal sites of second molars did not significantly differ by third molar removal status. Incident caries at the distal surfaces of second molars occurred in fewer than 1% of all sites. CONCLUSIONS: Rates of paresthesia and temporomandibular joint disorder were higher after third molar removal. Periodontal attachment loss and incident caries at the distal sites of second molars were not affected by extraction status.

Classification and treatment of Class II subdivision malocclusions.

INTRODUCTION: Patients with Class II subdivision malocclusions are a challenge for clinicians because reestablishing symmetry in 1 arch or both arches is often a treatment goal. In patients with mandibular skeletal asymmetry, surgery is often a treatment option. However, patients may be unwilling to undergo surgery, and other options might have to be considered. The aim of this study was to evaluate the etiologies and outcomes of Class II subdivision patients treated at the University of Washington graduate orthodontic clinic in Seattle from 1995 through 2011. METHODS: A search of patients treated between 1995 and 2011 resulted in the identification of 110 consecutively treated Class II subdivision subjects with complete records. Ninety-eight subjects could be classified into 1 of 3 groups, based on midline position and dental or skeletal etiology. Initial and final models were used to measure the peer assessment rating scores, midlines, overjet, overbite, and molar positions. Initial and final cephalograms were traced and measured. Charts were reviewed for information regarding treatment. RESULTS: Twenty-five percent of the 98 subjects had their maxillary and mandibular midlines coincident with the facial midline; their asymmetries were due to a maxillary posterior dental asymmetry. Another 15% had maxillary midlines deviated from their facial midlines, caused by maxillary anterior and posterior dental asymmetry. About 50% of the subjects had mandibular midlines that were not coincident with their facial midlines, and most of them exhibited some degree of mandibular skeletal asymmetry. Over the past 15 years, treatment strategies used at the University of Washington indicated trends toward less surgery, fewer extractions, less use of headgear, and more reliance on fixed functional appliances. Ideal correction of midlines was not always achieved, especially in patients with mandibular skeletal asymmetry, with undercorrection occurring more commonly than overcorrection. Final peer assessment rating scores were comparable, regardless of the origin of the asymmetry or the extractions status. Mandibular incisor proclination was increased when fixed functional appliances were used, as well as when a Class I molar relationship was the target for the Class II side. CONCLUSIONS: Class II subdivision malocclusions were grouped into 3 main categories; the largest category was mandibular asymmetry. Interesting trends were noted with regard to treatment strategies, midline and molar corrections, and mandibular incisor proclination.

Effectiveness of MI Paste Plus and PreviDent fluoride varnish for treatment of white spot lesions: a randomized controlled trial.

INTRODUCTION: White spot lesions are a common sequela of orthodontic therapy. In this parallel-group randomized trial, we assessed the effectiveness of 2 agents commonly used to ameliorate white spot lesions compared with a normal home-care regimen. METHODS: Patients aged 12 to 20 years were recruited from the offices of orthodontists and dentists who belonged to the Practice-based Research Collaborative in Evidence-based Dentistry network. The patients had their orthodontic appliances removed within the past 2 months and had at least 1 white spot lesion affecting their maxillary incisors. The subjects were randomized to 1 of 3 arms: (1) an 8-week regimen of MI Paste Plus (GC America, Alsip, Ill), (2) a single application of PreviDent fluoride varnish (Colgate Oral Pharmaceuticals, New York, NY), and (3) usual home care (control). Photographs were taken at enrollment and 8 weeks later. Two panels consisting of 5 dental professionals and 5 laypersons assessed the before-and-after pairs of photographs in a blinded fashion. Objective assessments and self-assessments were also performed. RESULTS: One hundred fifteen subjects completed the study; 34 were assigned to the MI Paste Plus group, 40 to the fluoride varnish group, and 41 to the control group. The mean improvements assessed by the professional panel were 21%, 29%, and 27% in the MI Paste Plus, fluoride varnish, and control groups, respectively.The results from the lay panel were 29%, 31%, and 25%, respectively. Objective improvements in the surface affected were 16%, 25%, and 17%, respectively; self-assessments of improvement were 37% in all 3 groups. No assessments indicated significant differences between subjects in the active arms compared with the control arm. CONCLUSIONS: MI Paste Plus and PreviDent fluoride varnish do not appear to be more effective than normal home care for improving the appearance of white spot lesions over an 8-week period.

Medicaid and privately financed orthodontic patients have similar occlusal and psychosocial outcomes.

OBJECTIVE: This study compares occlusal and psychosocial outcomes from comprehensive orthodontic treatment in Medicaid (MC) and privately financed (private pay, PP) patients. METHODS: Two cohorts received comprehensive orthodontics: MC (n = 66); PP (n = 60). A calibrated, blinded examiner scored dental casts at baseline (pretreatment, T1) and after completing 2 years of treatment (posttreatment, T2) using the Peer Assessment Rating (PAR) and the Index of Complexity, Outcome, and Need (ICON). The prevalence of patients in the validated ICON categories for treatment need, complexity, and improvement were calculated. Questionnaires to assess body image (BI) and expectations/experiences were administered. Occlusal measures at T2 were compared after adjustment for baseline characteristics. Psychosocial measures were compared between and within groups. Occlusal and psychosocial associations were evaluated. RESULTS: MC was 1.3 years younger (P < 0.001) and had worse malocclusions at baseline (PAR 32 versus 25; P < 0.001); (ICON 64 versus 56; P = 0.06). After adjustment for age and initial severity, estimated average differences between groups at T2 (MC-PP) were slight: 1.5 [95 percent confidence interval (CI) -2.9, 5.9] and 2.4 (95 percent CI -4.4, 8.9) for PAR and ICON, respectively. More PP completed treatment under 2 years (85 percent versus 62 percent; P = 0.03). At baseline, both groups needed treatment, but MC malocclusions were more complex (P = 0.05). At T2, both groups were acceptable and there were no differences in ICON improvement categories. Group differences in psychosocial measures and associations between psychosocial and occlusal measures were evident in the "teeth" domain but weak or lacking elsewhere. CONCLUSIONS: Occlusal and psychosocial outcomes from orthodontics in MC and PP were comparable, despite worse MC malocclusions at baseline.

Bisphosphonates as a risk factor for adverse orthodontic outcomes: a retrospective cohort study.

INTRODUCTION: Bisphosphonates are a class of drugs commonly prescribed to treat osteoporosis. They act by decreasing the resorption of bone. Since tooth movement depends on bone remodeling, these drugs can impact orthodontic treatment. The purpose of this study was to evaluate the extent to which bisphosphonate therapy is a risk factor for poor orthodontic outcomes. METHODS: Orthodontists were invited to participate in the study by performing case reviews of women over age 50 who were treated from 2002 through 2008. Women who used bisphosphonates were compared with women who did not have a history of bisphosphonate use. Outcomes assessed included treatment time, osteonecrosis of the jaws, incisor alignment, incomplete space closure, and root parallelism. RESULTS: The records for 20 subjects with bisphosphonate exposure were collected, as well as records for 93 subjects without bisphosphonate exposure. In patients undergoing extractions, treatment times were significantly longer if they had a history of bisphosphonate use. No occurrences of osteonecrosis of the jaws were reported, nor did patients end treatment with incisor alignment discrepancies greater than 1 mm, regardless of bisphosphonate exposure. Among patients with extractions or initial spacing, there were higher odds of incomplete space closure (odds ratio, 13) and poor root parallelism (odds ratio, 26) at the end of treatment for patients using bisphosphonates. CONCLUSIONS: Bisphosphonate use is associated with longer treatment times among extraction patients, increased odds of poor space closure, and increased odds of poor root parallelism.

Long-term stability of anterior open-bite closure with bilateral sagittal split osteotomy.

INTRODUCTION: Maxillary impaction and bimaxillary osteotomies are used to treat anterior open-bite malocclusions but can have adverse soft-tissue effects. Correcting an anterior open bite with a single mandibular procedure avoids these undesirable soft-tissue effects, but the stability of this procedure is unknown. The purpose of this study was to assess the long-term stability of anterior open-bite correction with bilateral sagittal split osteotomy and rigid internal fixation. METHODS: Orthognathic surgical records of 1 oral surgeon were searched for all patients treated for anterior open bite with bilateral sagittal split osteotomy and surgical closing rotation of the mandible with rigid internal fixation. Cephalometric films from initial consultation, presurgery, postsurgery, orthodontic appliance removal, and a mean of 4.5 years after orthodontic appliance removal were collected, traced, and measured. RESULTS: Thirty-one patients fit the inclusion criteria for this study and had an initial mean open bite of -2.6 mm (SD, 1.1 mm). The patients experienced an average mandibular closing rotation of 3.7° (SD, 2.4°) with surgery. By orthodontic appliance removal, the mandible rotated open 1.1°, and incisor overlap was 1.4 mm (SD, 1.0 mm). Approximately 4.5 years after orthodontic appliance removal, the mean incisor overlap was maintained at 1.0 mm (SD, 1.0 mm), yet the mandible rotated open an additional 1.1°. Only 3 patients relapsed to no incisor overlap in the long term, and only 3 patients experienced relapse greater than 1 mm in the long term. CONCLUSIONS: Approximately 90% of the treated patients had a positive incisor overlap 4.5 years after orthodontic appliance removal. Despite a 60% loss of mandibular surgical closing rotation, only 10% of the patients relapsed to no incisor overlap in the long term. Bilateral sagittal split osteotomy and surgical closing rotation of the mandible by using rigid internal fixation should be considered a stable alternative in the treatment of mild-to-moderate anterior open-bite malocclusions.

Stability of treatment for anterior open-bite malocclusion: a meta-analysis.

INTRODUCTION: Anterior open-bite (AOB) treatment is considered challenging because of difficulties in determining and addressing etiologic factors and the potential for relapse in the vertical dimension after treatment. In this review, we compiled evidence on the long-term stability of the major therapeutic interventions for correcting AOB. Our objective was to review and compile evidence for the stability of surgical and nonsurgical therapies for AOB malocclusion. Our data sources were PubMed, EMBASE, Cochrane Library, limited gray literature search, and hand searching. METHODS: A search was performed of the electronic health literature on the stability of AOB after treatment. Hand searching of major orthodontic journals and limited gray literature searching was also performed, and all pertinent abstracts were reviewed for inclusion. Full articles were retrieved for abstracts or titles that met the initial inclusion criteria or lacked sufficient detail for immediate exclusion. Studies accepted for analysis were reviewed and their relevant data retrieved for pooling. The long-term stability estimates were pooled into nonsurgical and surgical groups, and summary statistics were generated. RESULTS: One hundred five abstracts met the initial search criteria, and 21 articles were included in final analyses. Rejected articles failed to exhibit follow-up times of 12 months or more, did not include measurements of overbite (OB), or did not meet inclusion criteria. All included articles were divided into a surgical group (SX) with a mean age of 23.3 years and a nonsurgical group (NSX) with a mean age of 16.4 years. All studies were case series. Random-effects statistical models were used to pool the mean OB measures before and after treatment and also at the long-term follow-up. The pretreatment adjusted means of OB were -2.8 mm for the SX and -2.5 mm for the NSX. AOB closures up to +1.6 mm (SX) and +1.4 mm (NSX) were achieved. Relapse in the SX group during the mean 3.5 years of follow-up reduced the OB to +1.3 mm; the NSX group relapsed to +0.8 mm in the mean 3.2 years of follow-up. Pooled results indicated reasonable stability of both the SX (82%) and NSX (75%) treatments of AOB measured by positive OB at 12 or more months after the treatment interventions. CONCLUSIONS: In the included case series publications, success of both the SX and NSX treatments of AOB appeared to be greater than 75%. Because the SX and the NSX were examined in different studies and applied to different clinical populations, no direct assessment of comparative effectiveness was possible. The pooled results should be viewed with caution because of the lack of within-study control groups and the variability among studies.

Retention: taking a more active role.

Retention may be particularly challenging after the correction of specific malocclusion features, such as tooth rotations, open bite and expansion, which are all inherently unstable. In this article, some indications for active retention are reviewed by highlighting a variety of clinical techniques and appliances. Active retention is discussed in relation to preservation of tooth alignment and in the three planes of space: sagittal, vertical and transverse. In some situations, an active retention regimen may be helpful to minimise or counteract relapse after orthodontic treatment and to improve patient satisfaction during the typically lengthy post-treatment period.