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.

Does planned molar intrusion with aligners assist with closure of anterior open bite?

INTRODUCTION: This study aimed to determine whether prescribed molar intrusion, with or without virtual occlusal bite-blocks (BB), resulted in actual molar intrusion and assisted with anterior open bite (AOB) correction in adult patients treated with Invisalign clear aligners (Align Technology, Santa Clara, Calif). METHODS: A retrospective study was conducted with 36 adult patients with AOB. Subjects were divided into 2 treatment groups: planned molar intrusion (PMI) and no-PMI (No-PMI). PMI was obtained from the tooth movement tables in the ClinCheck software. Patients with PMI were further categorized by the presence or absence of virtual posterior BB (PMI-BB and PMI-No BB, respectively). Treatment success was determined on the basis of positive vertical incisor overlap in posttreatment cephalograms. Treatment changes were assessed using pretreatment and posttreatment cephalometric radiographs (Welch 2-sample t test, 95% confidence interval, P = 0.05). Finally, treatment stability was assessed at least 1-year posttreatment using the Photographic Open Bite Severity Index (POSI). RESULTS: There were 15 patients with No-PMI and 21 without PMI (total n = 36). The mean overbite change was 2.5 ± 1.0 mm for No-PMI and 3.2 ± 1.8 mm for patients with PMI (P = 0.12). All patients had positive vertical incisor overlap in posttreatment cephalograms, indicating 100% treatment success. Open bites were corrected primarily by incisor retroclination and extrusion in both treatment groups. The average measured molar intrusion for the PMI group was 0.71 mm greater than the change for the No-PMI group, but the difference was not statistically significant after controlling for potentially confounding variables (P = 0.074). A total of 14 patients from the original sample were assessed for stability using the POSI analysis. Of those, 12 (85.7%) had a POSI score of 0. CONCLUSIONS: Regardless of whether the molar intrusion was planned or not, the modality of AOB correction with Invisalign clear aligners was primarily incisor extrusion and retroclination. Overall, aligners are an effective appliance for the treatment of adult AOB. Based on our limited sample, treatment stability was similar to that reported for fixed appliances.

Bias in the superimposition of lateral cephalograms in adult patients with anterior open bite.

INTRODUCTION: Anterior open bite malocclusion can be treated nonsurgically using fixed appliances, clear aligners, or temporary anchorage devices (TADs). Proponents of clear aligners and TADs often attribute bite closure to molar intrusion and counterclockwise rotation of the mandibular plane. These changes may be supported by superimpositions. However, the process of creating a superimposition is subjective and may be influenced by practitioner bias. METHODS: The initial and final lateral cephalograms from 30 adult anterior patients with open bite were used in this study. Ten patients were treated with fixed appliances, 10 with clear aligners, and 10 with TADs. We asked 6 orthodontic graduate students and 6 orthodontic practitioners to complete superimpositions using these radiographs in 3 separate sessions. In the first session, the raters were told that all patients only received treatment with fixed appliances. In the second session, the raters were told that all patients were treated with clear aligners only, and in the third session, they were told all patients were treated with fixed appliances and TADs. Superimpositions were performed using Dolphin software, and each superimposition was saved as a Portable Document Format image. Change in the mandibular plane was the primary outcome and was assessed categorically (closed, no change, opened). Cephalometric values were measured and used to investigate the dental and skeletal changes associated with treatment. RESULTS: Although the raters demonstrated a slight tendency toward the mandibular plane closing or staying the same when told the treatment was clear aligners or TADs, these differences were not statistically significant. A high degree of intrarater and interrater variability in the mandibular plane change was present in all 3 superimposition sessions. The measurements from the lateral cephs showed significant changes for overbite and incisor vertical and angular movements. Almost no change was observed in anterior facial height, mandibular plane angle, or vertical movement of the first molars. CONCLUSIONS: This study did not observe a significant amount of superimposition bias. However, there was considerable intrarater and interrater reliability. This suggests that the same initial and final cephs may be interpreted very differently on the basis of the subjective superimposition of the raters.

En-masse retraction of maxillary anterior teeth with the Double J retractor and palatal miniscrews: A case report.

A double J retractor and palatal miniscrews were applied to retract maxillary anterior teeth without brackets after repeated periodontal flare-ups. The line of action passing through the center of resistance of maxillary anterior teeth and the moment generated by palatal miniscrews via torquing springs successfully controlled the overbite and incisor torque during space closure. In addition to en-masse retraction without brackets, it is also possible to combine this setup with labial fixed appliances or clear aligner treatment.

Outcomes used in trials regarding the prevention and treatment of orthodontically induced white spot lesions: A scoping review.

INTRODUCTION: The objective was to identify and summarize the outcomes and evaluation methods used in clinical trials regarding the prevention and treatment of orthodontically induced white spot lesions (WSLs). METHODS: Three electronic databases were searched to identify studies that were (1) clinical trials on prevention and/or treatment of orthodontically induced WSLs, (2) reported in English, and (3) published between January 2010 and October 2019. At least 2 authors assessed the eligibility and extracted the characteristics, outcomes, and evaluation methods from included studies. All disagreements were resolved through discussion. RESULTS: Among 1328 studies identified, 51 were eligible and included. A total of 48 different outcomes and 11 different evaluation methods were used in these studies. The most frequently used outcomes were WSLs clinical visual examination scores (n = 22, 43.1%), DIAGNOdent values (n = 14; 27.5%), fluorescence loss measured with quantitative light-induced fluorescence (QLF) (n = 10; 19.6%), and lesion area measured with QLF (n = 10; 19.6%). The most frequently used evaluation methods were clinical examination (n = 25; 49.0%), visual inspection by photographs (n = 15; 29.4%), DIAGNOdent (n = 14; 27.5%), and QLF (n = 10; 19.6%). None of the included studies reported data on quality of life. CONCLUSIONS: Substantial outcome heterogeneity exists among studies regarding the prevention and treatment of orthodontically induced WSLs. Most of the identified outcomes are aimed to assess morphologic changes of WSLs and may not reflect patient perspectives. REGISTRATION: The Core Outcome Set for trials on the prevention and treatment of enamel White Spot Lesions (COS-WSL) project was registered in the COMET Initiative database (No. 1399).

The effect of digital diagnostic setups on orthodontic treatment planning.

INTRODUCTION: This study aimed to evaluate whether viewing digital treatment simulations influenced orthodontic treatment planning decisions or practitioners' confidence in their selected plans. METHODS: Records of 6 patients representing different case types (eg, missing teeth, crowding, sagittal discrepancies) were collected. A total of 22 orthodontists and 7 orthodontic residents viewed these records and formulated treatment plans for each case, indicating their most recommended plan and up to 2 alternative plans. After treatment planning each case, digital setups of each treatment plan indicated by the practitioner were shown. The practitioners were then asked if they still recommended their original plan, or if they would now recommend a different plan. Their confidence levels in the success of their plans were recorded before and after viewing the setups. RESULTS: After viewing the digital setups, there was a significant change in the treatment plan for 9.2% of the cases. These included modifications like changing the extraction pattern or proposing space closure rather than opening space for an implant. In an additional 14.4% of the cases, treatment plans underwent partial changes, like adding interproximal reduction or temporary anchorage devices. Practitioner confidence levels increased after viewing the setups. In cases where the treatment plan changed, the practitioner's confidence level in the plan increased the most, and the final confidence level was uniformly high among all practitioners. Practitioners reported the most helpful features of digital setups were the ability to superimpose the setup with the original model, determine the amount of tooth movement needed, check the final incisal relationship (overjet and overbite), and establish the amount of interproximal reduction required. CONCLUSIONS: Viewing digital setups resulted in changes to the treatment plans in about 24% of the cases. The use of digital setups was associated with higher levels of confidence in the selected plans.

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.

The National Dental Practice-Based Research Network Adult Anterior Open Bite Study: Treatment recommendations and their association with patient and practitioner characteristics.

INTRODUCTION: This aim of this paper is to describe and identify the practitioner and patient characteristics that are associated with treatment recommendations for adult anterior open bite patients across the United States. METHODS: Practitioners and patients were recruited within the framework of the National Dental Practice-Based Research Network. Practitioners were asked about their demographic characteristics and their treatment recommendations for these patients. The practitioners also reported on their patients' dentofacial characteristics and provided initial cephalometric scans and intraoral photographs. Patients were asked about their demographic characteristics, previous orthodontic treatment, and goals for treatment. Four main treatment groups were evaluated: aligners, fixed appliances, temporary anchorage devices (TADs), and orthognathic surgery. Extractions were also investigated. Predictive multivariable models were created comparing various categories of treatment as well as extraction/nonextraction decisions. RESULTS: Ninety-one practitioners (mostly orthodontists) and 347 patients were recruited from October 2015 to December 2016. Increased aligner recommendations were associated with white and Asian patients, the presence of tongue habits, and female practitioners. TADs were recommended more often in academic settings. Recommendations for orthognathic surgery were associated with demographic factors, such as availability of insurance coverage and practitioner race/ethnicity, and dentofacial characteristics, such as anteroposterior discrepancies, more severe open bites, and steeper mandibular plane angles. Extraction recommendations were largely associated with severe crowding and incisor proclination. CONCLUSIONS: Both doctor and patient demographic factors, as well as dentofacial characteristics, were significantly associated with treatment recommendations for adult anterior open bite patients.

Effects of vibrational devices on orthodontic tooth movement: A systematic review.

INTRODUCTION: The aim of this systematic review was to investigate the ability of vibrational devices to increase the rate of orthodontic tooth movement or reduce pain associated with orthodontic treatment. METHODS: An electronic search for relevant randomized controlled trials (RCTs) was conducted using Medline via OVID (January 1, 1966, through March 30, 2018), and EMBASE, PubMed, and the Cochrane Central Register of Controlled Trials until August 2017. Hand searching of selected orthodontic journals was also undertaken. RESULTS: Through the electronic searches, 152 titles and abstracts were identified. From these, 10 articles were retrieved for review, and 4 of these met the inclusion criteria. Two additional articles were identified by hand searching. This resulted in 6 studies from 5 separate randomized controlled trials that were included in this systematic review. One RCT reported increased tooth movement with vibrational devices, but the other 4 RCTs reported no difference. Three studies investigated the effect of vibrational devices on pain reduction and found no effect. CONCLUSIONS: The ability of vibrational forces to increase the rate of tooth movement and reduce pain in orthodontic patients has been studied in several RCTs. The results from all but 1 of the included studies indicate no advantage from the use of vibrational devices during orthodontic treatment. Future studies should focus on total treatment duration, the mechanism by which vibration may speed up tooth movement, and the use of vibration with aligners. FUNDING: No funding was received for this review.

Effect of supplemental vibration on orthodontic treatment with aligners: A randomized trial.

INTRODUCTION: Supplemental vibration has been reported to accelerate orthodontic tooth movement and reduce discomfort. Our purpose was to investigate the effects of AcceleDent on Invisalign treatment. This randomized clinical trial was carried out in 2 orthodontic private practices with a 1:1 allocation ratio. METHODS: Adult patients who were beginning their orthodontic treatment were randomly allocated to either an active (A) or a sham (B) AcceleDent Aura device (OrthoAccel Technologies, Inc. Houston, TX). All patients were placed on a 1-week aligner change regimen, and fit was evaluated every 3 weeks. The outcomes were the ability to complete the initial set of aligners and the incisor irregularity measurements for those who completed their regimen of aligners. In addition, aligner compliance, pain levels, and oral health-related quality of life data were gathered from questionnaires. The subjects, investigators, and assessors were all blinded to the treatment arms. RESULTS: Twenty-seven subjects were randomized into 2 groups (A and B), 1 subject discontinued treatment, and 13 subjects were analyzed in each group. The Fisher exact test showed no significant difference in completion rates between the 2 groups (group A, 77%; group B, 85%; P = 1). Independent-sample t tests showed no significant difference between the final irregularity index or change in irregularity index between the 2 groups. Compliance was similar in both groups. The Wilcoxon rank sum test showed minimal differences in pain levels. Quality of life responses were similar in both groups. No serious harm was observed. CONCLUSIONS: We found no evidence that the AcceleDent Aura device impacts the ability to complete a series of aligners with a 1-week change regimen or the final alignment achieved in adult patients. It also had no significant effect on the reduction of orthodontic pain or oral health-related quality of life parameters when used with Invisalign.

Management of overbite with the Invisalign appliance.

INTRODUCTION: Most of the published literature on the management of overbite with the Invisalign appliance (Align Technology, Santa Clara, Calif) consists of case reports and case series. METHODS: In this retrospective study of 120 patients, we sought to assess the nature of overbite changes with the Invisalign appliance. Records were collected from 3 practitioners, all experienced with the Invisalign technique. The patients were consecutively treated adults (>18 years old) who underwent orthodontic treatment only with the Invisalign appliance. Patients with major transverse or anteroposterior changes or extraction treatment plans were excluded. The study sample included 68 patients with normal overbites, 40 with deepbites, and 12 with open bites. Their median age was 33 years, and 70% of the patients were women. RESULTS: Cephalometric analyses indicated that the deepbite patients had a median overbite opening of 1.5 mm, whereas the open bite patients had a median deepening of 1.5 mm. The median change for the normal overbite patients was 0.3 mm. Changes in incisor position were responsible for most of the improvements in the deepbite and open bite groups. Minimal changes in molar vertical position and mandibular plane angle were noted. CONCLUSIONS: The Invisalign appliance appears to manage the vertical dimension relatively well, and the primary mechanism is via incisor movements.

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.