The role ovariectomies and/or the administration of artificial female sex hormones play in orthodontic tooth movement: A systematic review

The objective was to assess how ovariectomy or the administration of artificial female sex hormones affects orthodontic tooth movement (OTM) with fixed appliances. An electronic search of indexed databases was completed without language or time restrictions up to June 2022. The following eligibility criteria were utilized: (i) prospective original controlled clinical studies; (ii) experimental studies on animal models; (iii) subjects undergoing orthodontic therapy with fixed appliances; (iv) clearly defined control groups not undergoing ovariectomy or administration of artificial female sex hormone; and (v) studies with experimental groups receiving the intervention of interest (ovariectomy or artificial female sex hormone administration). Review articles, letters to the editor, case reports, case series, commentaries, cross-sectional studies, retrospective studies, and studies with no well-defined control group were excluded. The quality of the available evidence and the risk of bias within the studies were assessed. All disagreements were resolved via discussion. Seven animal studies were included in the systematic review. Five studies reported that ovariectomy increased the rate of orthodontic tooth movement. Two studies reported that the administration of artificial female sex hormones decreased the rate of orthodontic tooth movement. There is an association between ovariectomies and OTM and between the administration of artificial female sex hormones and OTM. The full extent of the association remains unclear due to the biases that are present and the length of time of orthodontic therapy.

The second molar dilemma in orthodontics: to bond or not to bond?

OBJECTIVES

To compare orthodontic treatment (OT) outcome in adolescents undergoing nonextraction fixed OT with or without bonding of second molars using the score of the American Board of Orthodontics Cast Radiograph Evaluation (C-R-Eval).

MATERIALS AND METHODS

This study included healthy adolescents with skeletal Class I or mild Class II/Class III malocclusion, normal or deep overbite (OB), and mild-to-moderate dental crowding (<5 mm) who underwent nonextraction fixed OT with ("bonded" group) or without ("not-bonded" group) bonding of second molars. Patient treatment records, pre- and posttreatment digital models, lateral cephalograms, and orthopantomograms were assessed. The evaluated outcomes included leveling of the curve of Spee (COS), OB, control of incisor mandibular plane angle (IMPA), number of emergency visits (related to poking wires and/or bracket failure of the terminal molar tubes), treatment duration, and C-R-Eval. Treatment variables were compared across time points and among groups.

RESULTS

The sample included 30 patients (mean age 16.07 ± 1.80 years) in the bonded group and 32 patients (mean age 15.69 ± 1.86 years) in the not-bonded group. The mean overall C-R-Eval score was significantly higher (P < .001) in the not-bonded group (25.25 ± 3.98) than in the bonded group (17.70 ± 2.97). There were no significant differences in mean changes of COS, OB, IMPA, or treatment duration among groups. The mean number of emergency visits was significantly higher in the bonded (3.3 ± 0.6) than the not-bonded group (1.9 ± 0.4) (P < .001).

CONCLUSIONS

Bonding of second molars enhances the outcome of nonextraction fixed OT as demonstrated by the C-R-Eval without increasing treatment duration, irrespective of more emergency visits.

Artificial intelligence for treatment planning and soft tissue outcome prediction of orthognathic treatment: A systematic review

BACKGROUND

The accuracy of artificial intelligence (AI) in treatment planning and outcome prediction in orthognathic treatment (OGT) has not been systematically reviewed.

OBJECTIVES

To determine the accuracy of AI in treatment planning and soft tissue outcome prediction in OGT.

DESIGN

Systematic review.

DATA SOURCES

Unrestricted search of indexed databases and reference lists of included studies.

DATA SELECTION

Clinical studies that addressed the focused question 'Is AI useful for treatment planning and soft tissue outcome prediction in OGT?' were included.

DATA EXTRACTION

Study screening, selection and data extraction were performed independently by two authors. The risk of bias (RoB) was assessed using the Cochrane Collaboration's RoB and ROBINS-I tools for randomised and non-randomised clinical studies, respectively.

DATA SYNTHESIS

Eight clinical studies (seven retrospective cohort studies and one randomised controlled study) were included. Four studies assessed the role of AI for treatment decision making; and four studies assessed the accuracy of AI in soft tissue outcome prediction after OGT. In four studies, the level of agreement between AI and non-AI decision making was found to be clinically acceptable (at least 90%). In four studies, it was shown that AI can be used for soft tissue outcome prediction after OGT; however, predictions were not clinically acceptable for the lip and chin areas. All studies had a low to moderate RoB.

LIMITATIONS

Due to high methodological inconsistencies among the included studies, it was not possible to conduct a meta-analysis and reporting biases assessment.

CONCLUSION

AI can be a useful aid to traditional treatment planning by facilitating clinical treatment decision making and providing a visualisation tool for soft tissue outcome prediction in OGT.

REGISTRATION

PROSPERO CRD42022366864.

Correction: Santucci et al. Assessment of Posterior Dentoalveolar Expansion with Invisalign in Adult Patients. Int. J. Environ. Res. Public Health 2023, 20, 4318

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Temporomandibular Disorders: Implications in Restorative Dentistry and Orthodontics

Over the past several decades, the science of restorative/reconstructive dentistry and orthodontics has evolved tremendously, following sound principles passed down from robust literature and scientific rationale. These principles have been solid and instrumental in enhancing dentistry, from a single tooth restoration to complex full-mouth rehabilitations. However, it must be noted that some of the principles and philosophies followed over these decades have been questioned based on the advances in science, technology, and evidence-based medicine. The scenario became complex when clinicians were faced with the question of guidance for optimum joint and muscle health as related to restorative dentistry and orthodontics.

Mini-implant assisted posterior intrusion: A quantification of anterior bite closure in nongrowing subjects

INTRODUCTION

This study aimed to identify the vertical radiographic changes in nongrowing patients after treatment of anterior open bites (AOBs) using mini-implant assisted intrusion and to provide a predictive model to quantify the achievable intrusion.

METHODS

This retrospective radiographic study evaluated the dentoskeletal changes in adults using orthodontic mini-implants in 53 treated patients with AOB. Radiographs before and after posterior intrusion were utilized to evaluate the associated changes. Conventional cephalometric analyses provided data for assessment. A paired t test was used to identify significant changes. A regression model (best subsets selection algorithm) was generated to quantify the relationship between mini-implant-assisted intrusion and the resultant change in overbite. A matched, untreated control sample was used for comparison.

RESULTS

One hundred percent of AOBs were corrected using mini-implant-assisted intrusion of the maxillary molars. The overbite increased by an average of 3.6 mm. The average amount of maxillary first molar intrusion was 2.67 mm. The mandibular first molar moved an average of 1.93 mm closer to the palatal plane because of an average clockwise mandibular rotation of 0.78°. The occlusal plane steepened by an average of 3.95°. If all other inputs are held constant, 1 mm of intrusion of the maxillary first molar results in a 0.86 mm increase in overbite.

CONCLUSIONS

Mini-implant-assisted intrusion successfully treated AOB in adults with significant dentoalveolar but no significant skeletal changes. An average of 2.67 mm of intrusion of the maxillary first molars is achievable with this method showing that 1 mm of intrusion of the maxillary first molar increased overbite by 0.86 mm. Longer periods of intrusion resulted in greater amounts of bite closure.

Assessment of Posterior Dentoalveolar Expansion with Invisalign in Adult Patients

PURPOSE

The primary aim was to evaluate dentoalveolar expansion with Invisalign clear aligners comparing linear measurements in ClinCheck vs. cone beam computed tomography (CBCT). This would enable an assessment of to what extent expansion gained from Invisalign clear aligners was due to buccal tipping and/or bodily translation of the posterior teeth. The study also evaluated the predictive value of Invisalign ClinCheck^® (Align Technology, San Jose, CA, USA) to final outcomes.

METHODS

The orthodontic records of thirty-two (32) subjects comprised the sample to conduct this study. Linear values of the upper arch width were measured for premolars and molars at two different points (occlusal and gingival) utilized for ClinCheck^® measurements and three different points for CBCT measurements before (T₀ and after treatment (T₁). Paired T-tests at a significance level of 0.05 were used for analyses.

RESULTS

Expansion was found to be possible with Invisalign clear aligners. However, more expansion was measured at the cusp tips compared to gingival margins (p < 0.0001), indicating more tipping was occurring than bodily translation. ClinCheck^® also showed a significant overestimation of the amount of expansion capable, with nearly 70% expression in the first premolar area, and the expression decreased as one moved posteriorly with only 35% expressed at the first molar area (p < 0.0001).

CONCLUSIONS

Dentoalveolar expansion with Invisalign is achieved through buccal tipping of posterior teeth and bodily translation; and there is a significant overestimation of the amount of expansion achieved between ClinCheck^® and clinical results.

Association between nonextraction clear aligner therapy and alveolar bone dehiscences and fenestrations in adults with mild-to-moderate crowding

INTRODUCTION

This study aimed to assess the association between nonextraction clear aligner therapy (CAT) and the presence of alveolar bone dehiscences (ABDs) and fenestrations (ABFs) in adults with mild-to-moderate crowding.

METHODS

Cone-beam computed tomography images from 29 adults were obtained before and immediately after nonextraction CAT. Total root lengths were evaluated in axial and cross-sectional slices. Linear measurement for dehiscence (LM-D) was defined as the distance between the alveolar crest to the cementoenamel junction of each root (critical point set at 2 mm). Linear measurement for fenestration (LM-F) was recorded when the defect involved only the apical one-third of a root (critical point set at 2.2 mm). Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs were recorded before and immediately after nonextraction CAT at buccal and lingual root surfaces. Binary logistic regression analyses and repeated measures analyses of variance were performed.

RESULTS

Counts of ABDs/ABFs and magnitudes of LM-Ds/LM-Fs increased at most jaw locations and root surfaces. Nonextraction CAT was associated with an increased presence of ABDs and ABFs. Nonextraction CAT was associated with a higher magnitude of LM-Ds but not LM-Fs.

CONCLUSIONS

Immediate posttreatment cone-beam computed tomography scans showed that nonextraction CAT is associated with increased ABDs and ABFs in adults with mild-to-moderate crowding.

Comparative assessment of chewing sugar-free gum and conventional analgesic drugs in alleviating self-reported pain associated with fixed orthodontic appliances: A systematic review and meta-analysis

OBJECTIVE

To compare the effect of chewing sugar-free gum towards alleviating self-reported orthodontic treatment (OT) pain compared with conventional analgesic drugs (CADs).

SEARCH SOURCES

An unrestricted search of indexed databases and manual searching was performed up to September 2021.

DATA SELECTION

Randomised controlled trials (RCTs) comparing the impact of chewing gum and CADs on relieving self-reported orthodontic pain were included.

DATA EXTRACTION

Data screening, extraction and risk of bias (RoB) assessment were performed by two authors. Meta-analyses were performed using a random-effects model. The quality of available evidence was assessed using the Grades of Recommendation, Assessment, Development and Evaluation approach.

RESULTS

Nine RCTs were included. Eight RCTs used the Visual Analogue Scale for self-reported pain assessment, while one RCT used the Numeric Rating Scale. Five RCTs had a high RoB and four RCTs had a moderate RoB. Power analysis for sample size estimation was performed in six RCTs. Separate meta-analyses were performed by pooling quantitative data from five RCTs that compared self-reported orthodontic pain between chewing gum and ibuprofen groups for the following timepoints: baseline; immediately; 2 hours; 6 hours; bedtime; 24 hours; 2 days; 3 days; 5 days; and 7 days after the placement of orthodontic appliances. None of the timepoints individually indicated a difference in self-reported pain scores between chewing sugar-free gum and ibuprofen groups. The overall level of evidence was very low.

CONCLUSION

Chewing sugar-free gum is a potentially useful alternative to CADs towards pain alleviation during fixed OT.

Effectiveness of Curcumin in Reducing Self-Rated Pain-Levels in the Orofacial Region: A Systematic Review of Randomized-Controlled Trials

The aim was to systematically review randomized controlled trials (RCTs) that assessed the effectiveness of curcumin in reducing self-rated pain levels in the orofacial region (OFR). The addressed focused question was “Is curcumin effective in reducing self-rated pain levels in the OFR?”. Indexed databases (PubMed (National Library of Medicine), Scopus, EMBASE, MEDLINE (OVID), and Web of Science) were searched up to and including February 2022 using different keywords. The inclusion criteria were (a) original studies (RCTs) in indexed databases; and (b) studies assessing the role of curcumin in the management of pain in the OFR. The risk of bias was assessed using the Cochrane risk of bias tool. The pattern of the present systematic review was customized to primarily summarize the pertinent information. Nineteen RCTs were included. Results from 79% of the studies reported that curcumin exhibits analgesic properties and is effective in reducing self-rated pain associated with the OFR. Three studies had a low risk of bias, while nine and seven studies had a moderate and high risk of bias, respectively. Curcumin can be used as an alternative to conventional therapies in alleviating pain in the OFR. However, due to the limitations and risk of bias in the aforementioned studies, more high-quality RCTs are needed.

Anti-nociceptive efficacy of essential oil-based extracts for the management of orofacial pain: a systematic review of available evidence

OBJECTIVE

Experimental studies have shown that essential oil (EO)-based extracts derived from medicinal plants exhibit antinociceptive activity. The aim of the present systematic review was to assess the anti-nociceptive efficacy of EO-based extracts for the management of orofacial pain (OFP).

MATERIALS AND METHODS

To address the focused question "Are EO-based formulations effective for the management of OFP disorders?", indexed databases were searched without time and language restrictions using the preferred reporting items for systematic reviews and meta-analysis guidelines. Risk of bias (ROB) was assessed.

RESULTS

Eight studies were included and processed for data extraction. Two studies were clinical (one in adults and one in children) and 6 were performed in rodents. Results from one clinical study showed that inhalation of EO-extracts does not affect subjective toothache scores; and results from the study on children reported that inhalation of lavender oil reduces anxiety and pain during and after tooth extraction. Results from all experimental studies showed that administration of EO-extracts reduces orofacial nociceptive behavior. The ROB was high in 50% and 83.3% of the clinical and experimental studies, respectively.

CONCLUSIONS

The anti-nociceptive efficacy of EO-extracts for the management of OFP remains debatable. Further well-designed and power-adjusted randomized clinical trials are needed in this regard.

Influence of low-level-laser therapy on the stability of orthodontic mini-screw implants. A systematic review and meta-analysis

BACKGROUND

The influence of low-level-laser therapy (LLLT) on the stability of orthodontic mini-screw implants (MSIs) has not been systematically reviewed.

OBJECTIVES

The aim was to assess the influence of LLLT on the stability of orthodontic MSIs.

METHODS

An unrestricted search of indexed databases was performed.

SELECTION CRITERIA

Randomized controlled clinical trials (RCTs) investigating the influence of LLLT on orthodontic MSI stability.

DATA COLLECTION AND ANALYSIS

Two authors independently performed study retrieval and selection, and data extraction. The risk of bias (RoB) of individual studies was assessed using the Cochrane RoB Tool for RCTs. Meta-analyses were performed separately for RCTs using periotest and resonance frequency analysis (RFA) to measure MSI stability; and a random effects model was applied. Subgroup analyses were performed based on the time-points of MSI stability evaluation. The quality of available evidence was evaluated using the Grades of Recommendation, Assessment, Development, and Evaluation approach.

RESULTS

Initially, 1332 articles were screened. Six RCTs with a split-mouth design were included. The periotest was used in 4 RCTs and 2 RCTs used RFA to measure MSI stability. All RCTs had a low RoB. Subgroup analyses based on periotest indicated that MSIs treated with LLLT had significantly higher stability than untreated MSIs at 21 and 30 days [weighted mean difference (MD) = -2.76, confidence interval (CI): [-4.17, -1.36], P-value = 0.0001) and at 60 days (weighted MD = -3.47, CI: [-4.58, -2.36], P < 0.00001); and the level of certainty was high. Subgroup analyses based on RFA showed higher stability of MSIs treated with than without LLLT at 56 and 60 days (standardized MD = 0.82, CI: [0.32, 1.32], P = 0.001), and at 70 and 90 days (standardized MD = 0.86, CI: [0.36, 1.36], P = 0.0007); and the level of certainty was moderate.

LIMITATIONS

Due to limited number of relevant studies, it was not possible to perform sensitivity analysis, subgroup analyses for patient and intervention-related characteristics, and reporting biases assessment.

CONCLUSIONS

The role of LLLT on the secondary stability of MSIs placed in patients undergoing OT remains debatable.

CLINICAL TRIAL REGISTRATION

PROSPERO (CRD42021230291).

Changes in Airway Dimensions Following Non-extraction Clear Aligner Therapy in Adult Patients with Mild-to-moderate Crowding

AIM AND OBJECTIVE

This retrospective study aimed to assess changes in airway dimensions with non-extraction clear-aligner-therapy (NE-CAT) in adult patients with mild-to-moderate crowding.

MATERIALS AND METHODS

Cone-beam computed tomographic images were evaluated for 24 adults (16 females and 8 males) with mild-to-moderate crowding, and Class I or mild skeletal Class II malocclusion before and after NE-CAT. Cross-sectional and volumetric airway measurements were performed at the level of the nasal cavity, upper pharyngeal airway space (UAS), and lower pharyngeal airway space (LAS). The Frankfort-mandibular plane angle (FMA), point A-nasion-point B (ANB) angle, and intermolar width were measured. A paired t-test was used to assess changes in airway measurements. Linear regression analyses were performed to identify predictors of the pharyngeal airway volume change at the levels of the UAS and LAS.

RESULTS

There was a significant decrease (p = 0.004) in UAS mean volume (486.63± 752.73 mm³), LAS mean volume (p = 0.006), and cross-sectional airway area (p = 0.022) (1536.92± 2512.02 mm³ and 34.66± 69.35 mm², respectively) with NE-CAT. The mean airway volume of the nasal cavity, mean cross-sectional airway areas of the nasal cavity and UAS, and mean minimum cross-sectional pharyngeal airway area did not change significantly with NE-CAT. Changes in pharyngeal airway volume were not significantly associated with patients' age, gender, treatment duration, pretreatment ANB angle, and changes in FMA and maxillary first intermolar width with NE-CAT.

CONCLUSION

Significant changes in the pharyngeal airway dimensions of the UAS and LAS with NE-CAT in adult patients with mild-to-moderate crowding were identified.

CLINICAL SIGNIFICANCE

The results of the present study show that NE-CAT is not associated with an improvement in airway dimensions in adults with mild to moderate crowding.

Patients' and parents' expectations of orthodontic treatment in university settings

INTRODUCTION

The primary aim was to compare patients' and parents' orthodontic treatment expectations at the Eastman Institute for Oral Health, University of Rochester, Rochester, NY (UR) in the United States. Secondary aims were to assess the association between sociodemographic factors and UR participants' expectations; and compare participants' expectations between UR, Academic Centre for Dentistry Amsterdam (ACTA) and King's College Dental Hospital, London, United Kingdom (KC) (previously published data).

METHODS

One hundred and forty participants [70 patients and one of their parents (n = 70)] completed a validated questionnaire (10 questions) to measure orthodontic treatment expectations before screening at the Orthodontic Department at UR. Various sociodemographic factors were assessed. The paired t test (for continuous responses) and the Fisher exact test (for categorical responses) were used to compare UR patients' and parents' responses. Two-sample t test and the Fisher exact test were used to compare participants' responses among sociodemographic groups. One-way analysis of variance followed by the Tukey test, and the Fisher exact test were used to compare participants' responses between UR, and ACTA and KC (data collected from previous publications). A multiplicity correction was performed to control the false discovery rate.

RESULTS

Patients at UR expected less check-up and diagnosis, and less discussion about treatment at the initial visit, more dietary restrictions, and less improvement in smile esthetics and social confidence with orthodontic treatment than parents. Participants' responses differed by sociodemographic factors at UR and between UR, ACTA, and KC.

CONCLUSIONS

Expectations of orthodontic treatment differ between patients and their parents, are associated with sociodemographic factors, and vary among United States and European University centers.

Influence of mini-screw implant-assisted intrusion on orthodontically induced inflammatory root resorption: a systematic review

AIM

To systematically review indexed literature related to the influence of mini-screw implant (MSI)-assisted intrusion on orthodontically induced inflammatory root resorption (OIIRR).

METHODS

Indexed databases were searched without time and language restrictions using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The inclusion criteria were: (a) original studies; (b) patients/subjects undergoing MSI-assisted intrusion; and (c) tomographic and/or histological assessment of OIIRR. Letters to the Editor, commentaries, case reports/series, reviews, and studies based on two-dimensional radiographic assessment of OIIRR were excluded. For experimental and clinical studies, the risk of bias assessment was performed using the Systematic Review Centre for Laboratory animal Experimentation risk of bias tool and the Risk of Bias in Non-randomized Studies of Interventions guidelines, respectively.

RESULTS

The initial search yielded 453 studies, out of which 6 (3 clinical and 3 on animal-models) were included. The clinical studies were performed on males and females with a mean age ranging between 16.07 and 25.5 years. Duration of the clinical studies ranged from 3.8 to 9 months. The animal studies were performed on mini-pigs, rats, and dogs. The mean age in the studies on rats and mini-pigs was 2.76 and 18 months, respectively. In the study on canine models, mean age was not reported. In all studies, MSI-assisted intrusion was shown to cause OIIRR. Power analysis was performed in one study. All studies had a moderate risk of bias.

CONCLUSIONS

MSI-assisted intrusion is a risk factor for OIIRR; however, from a clinical perspective, further well-designed and power-adjusted studies are needed.

Influence of thyroxine supplementation on orthodontically induced tooth movement and/or inflammatory root resorption: A systematic review

The role of thyroxine administration on orthodontically induced tooth movement and/or inflammatory root resorption remains unclear. The aim was to assess the influence of thyroxine administration on orthodontically induced tooth movement and/or inflammatory root resorption. The study protocol was registered in PROSPERO (CRD42020164151). An electronic search of indexed databases was conducted without time or language restrictions up to and including May 2020. The following eligibility criteria were imposed: (a) original prospective controlled clinical studies and/or experimental studies on animal models; (b) subjects undergoing orthodontic therapy with fixed appliances; (c) presence of a control group [orthodontic tooth movement without thyroxine administration]; and (d) intervention: orthodontic tooth movement with thyroxine administration. Review articles, commentaries, letters to the editor, case reports/series, studies with no control group, cross-sectional studies, retrospective studies and studies where thyroxine was administered along with other interventions such as calcitonin and prostaglandins were excluded. Quality of available evidence and risk of bias within studies were assessed. Any disagreements were resolved via consensus discussions. Based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, 8 animal studies were included. Four studies reported that thyroxine administration increases the rate of orthodontic tooth movement; 3 studies did not show a significant difference. Three studies showed that thyroxine administration decreases orthodontically induced inflammatory root resorption; 2 studies found no significant difference. The risk of bias among studies was high. In conclusion, the influence of thyroxine administration on orthodontic tooth movement and/or orthodontically induced inflammatory root resorption in animal models remains unclear.

Long-term 3-dimensional stability of mandibular advancement surgery

PURPOSE

To evaluate 3-dimensional changes in the position of the condyles, rami, and chin from 1 to 3 years after mandibular advancement surgery.

MATERIALS AND METHODS

This prospective observational study used pre- and postoperative cone-beam computed tomograms of 27 subjects with skeletal Class II jaw relation and normal or deep overbite. An automatic technique of cranial base superimposition was used to assess positional and bone remodeling changes that were visually displayed and quantified using 3-dimensional color maps. Analysis of covariance with presence of genioplasty, age at time of surgery, and gender as explanatory variables was used to estimate and test adjusted mean changes for each region of interest.

RESULTS

The chin rotated downward and backward 1 to 3 years after surgery. Changes of at least 2 mm were observed in 17% of cases. Mandibular condyles presented with displacements or bone remodeling of at least 2 mm on the anterior surface (21% of cases on the left side and 13% on the right), superior surface (8% on right and left sides), and lateral poles (17% on left side and 4% on right). Posterior borders of the rami exhibited symmetric lateral or rotational displacements in 4% of cases.

CONCLUSION

In the hierarchy of surgical stability, mandibular advancement surgery is considered one of the most stable surgical procedures. However, 1 to 3 years after surgery, approximately 20% of patients had 2- to 4-mm changes in horizontal and vertical chin positions or changes in condylar position and adaptive bone remodeling.

Prediction of lip response to four first premolar extractions in white female adolescents and adults

OBJECTIVE

To develop models for predicting changes in lip position of Class I extraction patients.

MATERIALS AND METHODS

Pretreatment and posttreatment lateral cephalograms of 46 white female adults and 109 white female adolescents were examined. Mean pretreatment ages for the adolescent and adult groups were 12.2 +/- 1.2 years and 23.0 +/- 8.5 years, respectively. Subjects were treated with conventional edgewise mechanics. Multivariate prediction models were derived from a randomly selected sample of 119 subjects and validated on the remaining 36 subjects.

RESULTS

Adolescents demonstrated significant vertical and horizontal skeletal growth and treatment changes, while adults showed only small increases in anterior face height. While significant retraction of the upper and lower incisors occurred in both groups, the amounts were greater in adults than in adolescents. Ratios for horizontal hard tissue to soft tissue movements ranged from 1.4:1 to 1.1:1 and 1.3:1 to 1:1 for the upper (Ls) and lower (Li) lips, respectively. There were moderate relationships between horizontal lip and underlying hard tissue movements (correlations ranged from .57 to .78 for Ls and from .58 to .86 for Li). Multiple regressions to predict lip movements showed moderately strong relationships for the upper lip (R = .79 to .81) and strong relationships for the lower lip (R = .89 to .90). Two to three variables were necessary to predict vertical lip movements (R = .82 to .87). The validation sample showed no systematic biases and similar levels of accuracy.

CONCLUSIONS

Upper and lower lip retraction in four first premolar extraction cases can be predicted with moderately high levels of accuracy in white female adolescents and adults.

Masticatory Exercise as an Adjunctive Treatment for Hyperdivergent Patients

OBJECTIVE

This retrospective study was designed to evaluate the morphologic effects of masticatory muscle exercise as an adjunctive therapy for hyperdivergent patients treated with fixed orthodontic appliances.

MATERIALS AND METHODS

Three samples of 50 subjects were selected, including one sample treated with orthodontics combined with exercise, one sample treated with orthodontics only, and an untreated control sample. Subjects were matched on the basis of age, sex, mandibular plane angle (MPA), treatment duration, and treatment rendered. Patients in the treated exercise sample were instructed to clench their teeth together as hard as possible for 15 seconds and to repeat this process at least four times for a total of one minute; this one-minute exercise was to be performed as often as possible throughout the day. Morphologic data was derived from pre- and posttreatment lateral cephalograms.

RESULTS

Exercise with orthodontics produced significant (P < .05) increases in overbite compared to orthodontics alone. However, changes in vertical facial morphology were not significantly different between the two treated samples. Relative to untreated controls, both treated samples showed significantly greater increases in the MPA (S-N to Go-Me), Y-axis, and the lower to total facial height ratio; the treated samples also showed significantly less true forward mandibular rotation than the untreated controls.

CONCLUSION

Short-term clenching exercises performed daily are insufficient as an adjunct to traditional orthodontic treatment for correcting or controlling the vertical dimension.

Glass ionomer cements as luting agents for orthodontic brackets

The objectives of the present study were to (1) assess the shear bond strengths of resin-reinforced glass ionomer Fuji Ortho LC and GC Fuji Ortho cements under differing conditions and (2) compare their bonding performance with that of conventional resin composite bonding systems. A sample of 264 bovine incisors was divided into 22 groups of 12 teeth each and bonded with SPEED central incisor brackets. Enamel surfaces of the teeth in the two experimental groups were conditioned according to the manufacturer's instructions; moreover, groups unconditioned before bonding were also included under both wet and dry conditions. A self-cure composite resin (Phase II) and a light-cure composite resin (Transbond XT) served as controls and were etched with 37% phosphoric acid and bonded in a dry field. After incubation at 37 degrees C for 24 hours and for seven days, the specimens were tested to failure with a shear force in an Instron machine. The Adhesive Remnant Index (ARI) was used to assess the amount of resin left on the enamel surfaces after debonding. Selected specimens were examined using scanning electron microscopy. Statistical analyses included analysis of variance tests, t-tests, and correlation coefficient calculations and showed that no significant difference existed between the glass ionomer cements under wet or dry conditions, provided the enamel was conditioned with 10% polyacrylic acid before bonding. Both glass ionomer cements were thus acceptable for bonding. Transbond XT had the highest mean shear bond strength irrespective of the incubation period. A positive correlation was obtained between the ARI scores and bond strength.

Adhesion of bonded orthodontic attachments to dental amalgam: In vitro study

Bonding orthodontic attachments to molars is difficult in the presence of extensive buccal amalgam restorations. The purposes of this study were (1) to examine different amalgam surface preparations, (2) to examine properties of adhesive cements to amalgam, (3) to determine the most shear-resistant bonding technique and (4) to discuss whether these shear bond strengths were of adequate magnitude to be of clinical acceptability. The sample consisted of 108 standardized amalgam cylinders divided into 9 groups of 12 based on surface treatment technique and resin type. SPEED brackets (Strite Industries, Cambridge, Ontario) were bonded to amalgam surfaces that were either polished, sandblasted with 50 microm aluminium oxide, or chemically corroded. Adhesives used were Phase II (Reliance Orthodontic Products Inc, Itasca, Ill), Panavia EX (J Morita USA Inc, Tustin, Calif), or C & B Metabond (Parkell, Farmingdale, NY). After thermocycling from 10 degrees C to 50 degrees C 10,000 times, all samples were tested for shear bond strength with the Universal Testing Machine (Instron Corporation, Canton, Mass). The results show significantly higher bond strengths for all of the resin systems when sandblasting of the amalgam surface is used (P <.0001). Only Panavia EX bonded strongly to polished samples, suggesting the presence of a chemical bond. Laboratory acceptable bond strengths to amalgam are possible. The surface characteristics of the amalgam appear to be more influential in the strength of the bond than does the nature of the resin.

Postretention mandibular incisor stability after premolar serial extractions

The purpose of this study was to evaluate the mandibular incisor alignment in serial extraction cases, using the longitudinal dental cast records of the Burlington Growth Center as a control sample. Various parameters were investigated and the statistical differences determined between the treated and untreated groups. The results were also compared with data from serial extraction groups that subsequently had orthodontic treatment. Untreated subjects and subjects treated only with serial extractions showed similar longitudinal changes. However, the extraction group that also received orthodontic treatment appeared to show more lower incisor crowding long-term. No predictors for stability of clinical significance could be determined. Mechanotherapy influences the craniofacial and dentoalveolar dimensions, which appear to cause more long-term lower incisor crowding.

A longitudinal evaluation of extraction versus nonextraction treatment with special reference to the posttreatment irregularity of the lower incisors

A tendency exists in contemporary orthodontics to pursue a completely non-extraction philosophy. Moreover, it has been shown that the extraction versus non-extraction debate is still with us. Controversy exists as to which treatment decision will eventually lead to orthodontic stability. It is thus imperative to conduct investigations on long-term changes of the dentition in both treatment regimens. The present study serves as an example of such a longitudinal study. A random sample, inclusive of both extraction and non-extraction treatments, was examined with respect to long-term stability and an assessment was made as to whether one treatment option favors success over the other. It was concluded that the correct initial treatment choice will not only lead to correction of the malocclusion, but will also ensure clinically acceptable stability with no significant differences between extraction and non-extraction treatments.

Terminology: semantics of postorthodontic treatment changes in the dentition

Correct terminology eliminates confusion in communication between clinicians, as well as between clinician and patient. Long-term stability seems to be an elusive goal, because the terminology in this respect eludes to the various changes occurring in the posttreatment dentition. However, a stable orthodontic result can be achieved when the physiologic changes that naturally occur in the dentition are considered as part of the long-term result. Standardization of terminology is therefore important.

Optimization of a procedure for rebonding dislodged orthodontic brackets

The purpose of this study was to compare shear bond strength (SBS) of bonded and rebonded orthodontic brackets following a variety of commonly used conditioning treatments and using both light-cured and self-cured composite resin systems. Brackets debonded during the initial determination of SBS were rebonded after the removal of residual resin from enamel surfaces using five different treatments: (1) Remove residual resin using a tungsten carbide bur, re-etch enamel surface, then bond a new bracket; (2) Remove resin from the base mesh with micro-etching then rebond the same bracket, (3) Remove residual resin from the enamel surface using resin-removing pliers, recondition the enamel with an air-powder polisher, then bond a new bracket; (4) Remove residual resin using a rubber cup and pumice, then bond a new bracket; (5) Remove residual resin using pliers alone, then bond a new bracket. The results revealed that the light-cured system produced higher shear bond strength in the initial bond than the self-cured system (p<0.005). Reconditioning the enamel surfaces using a tungsten carbide bur and acid-etching gave the highest SBS (difference 5.8 MPa; p<0.01) and clinically favorable fracture characteristics. The data suggest that the optimal procedure for rebonding dislodged orthodontic brackets is to resurface the enamel using a tungsten carbide bur, acid-etch the enamel, and use a new or re-use an old bracket after microetching.

Combinations of etchants, composite resins, and bracket systems: an important choice in orthodontic bonding procedures

The objectives of this investigation were: (1) to compare the shear bond strengths (SBS) of metal, ceramic, and plastic brackets using different concentrations of maleic and phosphoric acid gels and aqueous solutions, and (2) to determine if a relationship exists between the type of acid etchant and the location of resin after debonding. A sample of 210 bovine incisors was divided among three different bracket groups (Victory series metal, Transcend 6000 ceramic, Spirit MB plastic). Prior to bonding, enamel was acid-etched using 37% phosphoric acid (H3PO4) gel and aqueous solution, 10% maleic acid gel and aqueous solution, 10% H3PO4 gel and aqueous solution, or 2% H3PO4 aqueous solution. SBS testing and the adhesive remnant index (ARI) score provided insight into the effects of the bonding process on enamel. Resin tags associated with each etchant type were inspected under scanning electron microscopy (SEM). Statistical analyses (level of significance, p = 0.05) of the data showed significant differences among groups. It was concluded that specific acid-composite-bracket combinations are recommended for use in clinical orthodontic practice in order to achieve efficient bonding.

Radiographic localization of mandibular anesthesia landmarks

The objective of this study was to assess whether bony landmarks used for the standard inferior alveolar nerve block can be used to accurately determine the position of the mandibular foramen and whether panoramic radiographs are appropriate for this purpose. A total of 11 landmarks from 79 panoramic radiographs and 70 corresponding cases of oblique (45-degree) cephalometric radiographs were examined. Ten measurements of the distance from each landmark to the mandibular foramen, as well as 6 ratios from these distances, were calculated from all radiographs. The results showed that the position of the mandibular foramen was highly individualistic and not consistently related to traditional clinical landmarks. Panoramic radiographs were as good as oblique cephalometric radiographs for the locating of the mandibular foramen. No age or gender correlations were found. It was concluded that the mandibular foramen can be localized in panoramic radiographs but that its relation to bony landmarks is highly variable.

The effect of various storage methods and media on shear-bond strengths of dental composite resin to bovine dentine

A variety of media and methods have been used to store teeth used in bond-strength studies of resin restorative materials to dentine. This study examined the effect of 2 months of storage using 11 different methods and media on the shear-bond strength of Z100 resin composite to bovine dentine mediated by Scotchbond Multi Purpose adhesive. Freshly harvested teeth were used as controls. The results showed that 7 of the l1 storage methods or media were similar in shear-bond strengths and bond-failure characteristics. Four of the 11 methods (irradiation, or storage in thymol, methanol, and glutaraldehyde) resulted in significantly lower shear-bond strengths and atypical shear-bond failure, indicating that these are the least desirable methods of tooth storage for studies of this type. This study has further shown that if insufficient numbers of fresh teeth are available for studies of shear-bond strength, then freezing is the preferred method of storage for the registration of high shear-bond strengths. It is also apparent that further investigations are needed to examine what post mortem changes occur in dentine, whether these changes are modified by various storage conditions, and whether they have any significant effect on bonding of resin composites.

The relationship between bond strength and orthodontic bracket base surface area with conventional and microetched foil-mesh bases

The aim of this study was to test the effects on the shear bond strength by sandblasting bracket base surfaces, reducing base surface area, and etching enamel with various acid types. Four different base sizes, used as either standard (untreated), sandblasted or microetched were bonded with Phase II resin (Reliance Orthodontic Products, Inc.) in four groups of 12 bovine enamel specimens after enamel etching with phosphoric acid gel (37%), 37% phosphoric acid aqueous solution, 10% maleic acid gel, or 10% maleic acid aqueous solution. Storage of samples was for 7 days in distilled water at room temperature before shear bond testing with an Instron universal testing machine with a crosshead speed of 0.5 mm/min. Statistical analyses included the analysis of variance, the Student t test, and the Chi-square test at p < 0.05. An increase in shear bond strength was associated with sandblasting and microetching of foil-mesh bases for all base sizes (p < 0.05). No statistically significant difference in shear bond strength existed between the three larger base sizes, which indicated that shear bond strength is independent of surface area between 6.82 and 12.35 mm2. A reduction in bond strength was associated with the reduction of base surface area from 6.82 to 2.38 mm2 (p < 0.05). There appears to be no need to increase base surface area beyond 6.82 mm2. Aqueous maleic acid (10%) etching of the enamel was associated with the highest shear bond strength, with no statistically significant difference between the other three acids used.

Some "sealants" seal--a scanning electron microscopy (SEM) investigation

White spot lesions of enamel around orthodontic brackets as a result of demineralization have been well documented in the orthodontic literature. Various methods of treatment have been attempted to reduce or eliminate this danger. The purpose of this study was to evaluate, by means of scanning electron microscopy, the polymerization of the sealant layer around orthodontic brackets with direct and indirect methods of bonding. Twenty-four sound human lateral maxillary incisor teeth were collected, cleaned, divided equally into four groups A through D, and stored in 70% ethyl alcohol. Their buccal surfaces were pumiced, etched with 37% phosphoric acid for 1 minute, and washed under running water for 30 seconds. Metal brackets were bonded with the chemically cured BIS-GMA resin, Ortho Concise, as follows: group A, indirectly bonded with coping; group B, indirectly bonded without coping; and group C, directly bonded; light activated Transbond was used in group D, directly bonded brackets. After washing in alcohol for 20 seconds, all teeth were dried, and sectioned longitudinally, through the middle of the bracket. All were subjected to 5% hydrochloric acid for 30 seconds and then washed under running water for 30 seconds. After drying and sputter coating, the teeth were viewed under scanning electron microscopy. Groups A and D showed a sealant layer surrounding the brackets and covering the buccal enamel. Groups B and C showed total absence of a cured sealant layer around the brackets or surrounding enamel.(ABSTRACT TRUNCATED AT 250 WORDS)

Profile enhancement and cephalometric landmark identification

The reproducibility of two soft tissue landmarks (SN, V) and two anterior bony landmarks (A, ANS) was determined by three observers for three cephalometric techniques. The three techniques were aimed at soft tissue profile enhancement either by standard exposure control (technique 1), a hand-held metal shield covering the profile (technique 2), or a brass wedge in the collimator (technique 3). For each technique, the sample was restricted to 20 subjects with a skeletal convexity greater than +4 mm. The four landmarks were identified three times with 7-day intervals between readings. The figure-of-merit (or mean radius) method was used to assess the probability of "hitting" a target (landmark) area. The mean radius from the sample mean point of impact (MPI) ranged from 0.585 mm to 1.758 mm. For a specific landmark, the difference was never greater than 0.5 mm when grouped by observer and technique. No technique excelled in overall consistency for the identification of anterior bony and soft tissue landmarks. Techniques 1 and 3 produced the most consistent identification of points ANS and SN, but with no significant difference between the two techniques. Interacting factors prevented any recommendation regarding a preferential technique for the identification of points A and V. There is statistically no reason to recommend the use of a handheld, metal profile shield for more consistent landmark identification.

Malocclusion in patients presenting for orthodontic treatment

The Angle and Steiner classifications are used extensively in orthodontics. The prevalence of malocclusions in Caucasian patients living in the Western Cape was determined using both classifications and the degree of concordance of the data thus obtained was ascertained. A high prevalence of Angle Class I and II was found. No statistically significant differences could be demonstrated between the data obtained from the two systems although there were discrepancies. The implications of the findings are discussed and it is concluded that each classification system used on its own does not provide enough information for accurate diagnostic and treatment planning purposes.

A longitudinal evaluation of the anterior border of the dentition

Posttreatment changes of orthodontically treated dentitions are inherent to every orthodontic practice. Various studies have documented the ideal posttreatment dental and cephalometric norms that could pertain to stable long-term occlusal results. Clinically, changes in these parameters are often observed as mandibular incisor crowding. The purpose of this study was to evaluate the longitudinal changes in certain variables representing the anterior border of the dentition. Eighty-eight white subjects were assessed regarding stability of the dentition after edgewise orthodontic treatment. (44% nonextraction, 56% extraction) The following variables in proximity of the anterior limit of the dentition (overbite, overjet, mandibular arch length, upper and lower incisor position, Little irregularity index) were assessed and correlated with each other. The data were subjected to descriptive statistics, the Friedman test for significant changes and pairwise comparisons, and the Spearman correlation test. Mandibular intercanine width was not significantly altered during treatment, but although not significantly, p > 0.05 did decrease beyond the original measurement during posttreatment evaluation (mean 7 years after treatment). The other variables influenced by the orthodontic manipulation were all within normal ranges and remained stable. The arch length decreased significantly (p < 0.05) during the entire evaluation period and was the only variable not stable. It was concluded that: (1) sound treatment leads to attainment of ideal occlusal parameters, (2) mandibular intercanine expansion could lead to failure of results, (3) arch length change plays a major role in causing irregularity of mandibular incisors after treatment, and (4) patient education regarding posttreatment orthodontic changes is imperative.

Orthodontic microabrasive reproximation

Reproximation (enamel stripping) is described in the literature as a clinical procedure for correction of tooth size deviations. The objective of this study was to qualitatively assess, by means of scanning electron microscopy, (1) the differences exhibited on enamel with mechanical and chemical methods of stripping, and (2) the effect of a synthetic calcifying solution on the etched enamel. Part 1. Sixty human anterior teeth (10 complete sets) that were previously stored in 70% ethanol were subdivided into groups I and II. The teeth in group I were divided into five sets of six teeth mounted in a plaster block in the anterior arch form. Each set was stripped with one of the following mechanical abrasive methods: garnet disks, tungsten carbide and fine diamonds burs, coarse and fine diamond burs, diamond wheel and 3M strips, diamond-coated metal and 3M strips. The teeth in group II were similarly treated, except each set was subjected to a further microabrasive chemical stripping with 37% phosphoric acid used in conjunction with 3M strips. The teeth were then prepared for scanning electron microscopy, viewed, and photographed under magnification. Part 2. Ten human central incisor teeth were etched and used to study the effect of remineralization solutions at various time intervals. The results showed that teeth stripped by routine mechanical abrasive methods exhibited deep furrows and roughness. The teeth that received mechanical and chemical abrasive treatments showed a flattened, etched surface free of furrows. These etched surfaces showed marked crystal growth at 5 and 10 hours after remineralization suggesting the possibility of repair of the chemically altered enamel surface.

Shear peel bond strengths of esthetic orthodontic brackets

Anecdotal reports of bracket fracture and tooth damage associated with the use of certain esthetic orthodontic brackets have been reported in the literature. With the advent of new esthetic orthodontic brackets, the need has arisen to test the claims of the manufacturers. The objectives of this study were to determine: (1) shear peel bond strengths (SPBS) of various debonded orthodontic brackets, (2) SPBS of these rebonded esthetic brackets with and without use of silane, and (3) fracture sites of all groups examined. Seventy-five noncarious human premolar teeth were randomly divided into five groups (A through E). The teeth were cleaned, stored in 70% ethyl alcohol, and mounted for testing in the Instron machine. The following brackets were bonded to the teeth with Ortho-Concise bonding resin: (A) metal brackets, (B) Silkon brackets, (C) Transcend 2000 brackets, (D) debonded Transcend 2000 brackets, and (E) debonded silanized Transcend 2000 brackets. After wet storage at 37 degrees C for 7 days, the SPBS of brackets were recorded, and fracture sites observed. There were statistically significant differences between the SPBS of metal brackets when compared with the Transcend 2000 and the Silkon brackets. These groups exhibited clinically acceptable SPBS. Debonded silanized Transcend 2000 brackets showed clinically unacceptable SPBS. Fracture sites of metal and Transcend 2000 brackets were resin-bracket, whereas Silkon brackets fracture sites were predominantly resin-enamel.

The frontal sinus and mandibular growth prediction

The skeletal growth patterns of 103 subjects with Class I and III malocclusions were cephalometrically analyzed as advocated by Ricketts el al. to assess abnormal mandibular growth. The surface area (mm2) of the frontal sinus was assessed by a Summagraphics decoder linked to a microcomputer. The results indicate that there is a significant correlation between maxillary length, mandibular length, symphysis width, condylar length, and frontal sinus size on a lateral cephalogram. The frontal sinus can possibly be used as an additional indicator when one is predicting mandibular growth.