The effects of different orthodontic appliances upon microbial communities.

OBJECTIVES: Orthodontic appliances can promote accumulation of dental plaque, with associated enamel decalcification or gingival inflammation. The aim of this study was to examine longer-term microbiological changes during orthodontic treatment with fixed appliances. MATERIALS AND METHODS: Twenty-four orthodontic patients aged 11-14 years undergoing fixed appliance therapy were recruited into the study. Each was randomized for cross-mouth assignment of molar bands and bonded molar tubes to contralateral quadrants of the mouth. All patients received self-ligating brackets, but again using randomization, one upper lateral incisor bracket (left or right) also received an elastomeric ligature. Plaque samples from the molars and upper lateral incisors were obtained at intervals during treatment and up to 1 year after appliance removal. Denaturing gradient gel electrophoresis and 16S rDNA microarray were used to compare plaque microbial fingerprints. RESULTS: Plaque populations changed within 3 months of commencing treatment at all sites. The greatest differences in plaque composition were seen with self-ligating brackets with an elastomeric ligature. Post-treatment plaque associated with both types of molar attachment contained increased levels of periodontal pathogens Porphyromonas gingivalis, Tannerella forsythia, and Eubacterium nodatum, while Campylobacter rectus, Parvimonas micra, and Actinomyces odontolyticus were also elevated with bonds. CONCLUSIONS: The results suggest that orthodontic treatment may cause sustained changes in plaque microbiotas and that molar bond-associated plaque may have raised disease potential.

A randomized control clinical trial investigating orthodontic bond failure rates when using Orthosolo universal bond enhancer compared to a conventional bonding primer.

OBJECTIVE: This study assessed the in vivo bond failure rates of orthodontic brackets bonded using Orthosolo universal bond enhancer and compared it with the conventional bonding primer, Transbond XT. DESIGN: This was a single centre randomized controlled clinical study. SETTING: Department of Child Dental Health, Bristol Dental Hospital, Bristol, UK. MATERIALS AND METHODS: Thirty-three consecutive patients undergoing fixed orthodontic appliance therapy were included in this study. Using a split-mouth design, diagonally opposite quadrants were randomly allocated a primer, either Orthosolo universal bond enhancer (Ormco, Orange, CA, USA) or Transbond XT primer (3M Unitek, Monrovia, CA, USA). A total of 555 teeth were bonded using a conventional acid-etch technique. 277 received Orthosolo as their primer and 278 received the Transbond XT primer. Bond failures and their positions were recorded at six months. RESULTS: There was an overall bond failure rate of 1.26%. Four brackets failed in the Orthosolo group (0.72%) and three failed in the Transbond XT group (0.54%). CONCLUSION: There was no clinical or statistically significant difference in the in vivo bond failure rates between orthodontic brackets bonded using either Orthosolo universal bond enhancer or the conventional Transbond XT primer.

Tooth-size discrepancy and Bolton's ratios: the reproducibility and speed of two methods of measurement.

OBJECTIVE: To determine and compare the reproducibility and speed of two methods of performing Bolton's tooth-size analysis. DESIGN: Analysis of randomly selected clinical sample. SETTING: Bristol Dental Hospital, University of Bristol, United Kingdom. MATERIALS AND METHODS: Pre-treatment study casts of 150 patients were selected randomly from 1100 consecutively treated Caucasian orthodontic patients. Bolton tooth-size discrepancies and ratios were measured using two methods; one method employed entirely manual measurement and the Odontorule slide rule, while the other employed digital calipers and the HATS analysis software. Twenty study casts were measured twice, a week apart with both methods. Another three investigators also measured 20 study casts twice with the HATS analysis. RESULTS: There were small or no systematic errors within or between these two methods. A very significant difference was evident for mean time measurements between the two methods (mean time for HATS was 3.5 minutes and for Odontorule was 8.9 minutes). There was relatively high error variance of both methods of measurement as a percentage of the total variance. CONCLUSIONS: On-line electronic measurement was found to be more rapid than the manual method used. Both methods demonstrate relatively high random error and this has important consequences for the clinical use of Bolton's ratios.

Tooth-size discrepancy and Bolton's ratios: a literature review.

OBJECTIVES: To review the literature on Bolton's tooth-size discrepancies (TSD) with specific attention to the prevalence of TSD, and the possible influence of different classes of malocclusion, gender and racial group. Also examined were the validity of the standard deviations from Bolton's samples as an indicator of significant TSD, methods of measurement of TSD and their reproducibility. Based on the review, suggestions are made as to how future work could be improved. RESULTS AND CONCLUSIONS: Studies have reported from 20 to 30% of people with significant tooth-size anterior discrepancies and 5-14% for overall TSD. Bolton's original sample was appropriate for indicating what ratio is most likely to be associated with an excellent occlusion, but was not suited to indicating the size or prevalence of significant TSD. Most studies use samples that are not likely to be representative of orthodontic patients in the UK or, indeed, elsewhere. Although some statistically significant differences have been reported, gender and racial group seem unlikely to have a clinically significant influence on Bolton's tooth-size ratios. Class III malocclusions may have larger average ratios. Computerized methods of measurement are significantly more rapid. Most studies performed or reported their error analysis poorly, obscuring the clinical usefulness of the results. Studies are needed to properly explore the reproducibility of measurement of TSD and to appropriately determine what magnitude of TSD is of clinical significance.

Comparing a quality of life measure and the Aesthetic Component of the Index of Orthodontic Treatment Need (IOTN) in assessing orthodontic treatment need and concern.

OBJECTIVE: To compare the use of the Aesthetic Component (AC) of IOTN and the Child Perceptions Questionnaire (CPQ) in assessing orthodontic treatment need and concern. DESIGN: Cross-sectional observational study. SUBJECTS AND METHODS: The subjects were 204 children aged 10-12 years studying in 10 schools in Bristol, UK. They completed a questionnaire comprising the CPQ and questions regarding orthodontic concern. AC scores as rated by the child and by the calibrated examiner were recorded. MAIN OUTCOME MEASURES: CPQ scores were calculated from the responses in the questionnaire. AC scores and responses to questions regarding orthodontic concern were recorded. RESULTS: The children gave themselves lower AC scores compared to the examiner (p<0.001). The only section of the CPQ that correlated significantly with Examiner AC was the emotional impacts section (rho=0.151). CPQ scores had a slightly higher correlation with self-perceived AC than Examiner AC. However, the correlations were still very low. The emotional impacts section of CPQ (rho=0.332) and overall CPQ score (rho=0.282) were better than the examiner AC (rho=0.209) at reflecting how bothered the children were by the alignment of their teeth, and how upset they would be if they couldn't receive orthodontic treatment (rho=0.464, 0.428 and 0.214, respectively). Children with a normative need for orthodontic treatment, based on examiner AC did not have a worse oral health-related quality of life. CONCLUSION(S): The CPQ and IOTN AC measure different attributes. There should be a shift towards using quality of life measures to supplement the IOTN in assessing the perceived need for orthodontic treatment.

Self-ligating brackets: where are we now?

The current situation regarding self-ligating brackets is reviewed. Recent developments, clinical advantages, and remaining imperfections are described. The question of active versus passive ligation is scrutinized. The evidence regarding treatment efficiency is reviewed. Suggested clinical tips and changes of treatment mechanics are summarized and illustrated. Self-ligating brackets have reached a stage of design and production control, where the advantages are significantly greater than the remaining imperfections.

Development of a treatment outcome standard as a result of a clinical audit of the outcome of fixed appliance therapy undertaken by hospital-based consultant orthodontists in the UK.

Bristol's much-publicised cardiac surgery problems and subsequent enquiry(1) have drawn attention to the need for audit of treatment outcomes throughout all hospital specialties. Patient anxiety, government policy and the desire of the professions to re-establish public confidence, have further encouraged changes to the system. For medical and dental specialties, such challenges have already been taken up by the Royal Colleges with the establishment of clinical effectiveness committees. Hospitals have modified their procedures and, for consultants, yearly appraisal is already a reality. The Orthodontic Clinical Effectiveness Working Party of the Royal College of Surgeons of England (now the Clinical Effectiveness Committee of the British Orthodontic Society) set up this audit to measure the outcome of fixed appliance treatment and to establish a benchmark for the standard of treatment to be expected from a consultant orthodontist. This paper describes how the audit was carried out, presents the findings and goes on to discuss some of the wider issues involved in audit, clinical governance and appraisal. The Consultant Orthodontists Group of the British Orthodontic Society funded this audit and the results and data set of dental casts remain their property.

Self-ligating brackets and treatment efficiency.

A number of laboratory studies have shown very low levels of archwire friction for self-ligating brackets when compared to conventional ligation methods. However, justifiable reservations have been expressed as to the in vivo relevance of these findings. This study was designed to compare treatment efficiency with conventional fully programmed brackets and Damon SL self-ligating brackets. Thirty consecutively finished cases treated by the author with Damon SL brackets were compared with 30 matched cases treated by the author with conventional brackets. Parallel studies quantified the incidence of technical problems with Damon SL brackets and with conventional ligatures and also the chairside time required for ligation/slide closure and ligature removal/slide opening with these two bracket types. The Damon SL cases required an average of four fewer months and four fewer visits to be treated to an equivalent level of occlusal regularity as measured by the PAR scores.

The effects of torque control spurs in twin-block appliances.

The study compared the effects of torque control spurs on upper incisor retroclination and extrusion with two designs of a twin-block functional appliance in Class II/1 cases. The two designs were also compared with respect to anchorage loss in the lower arch and for patient compliance rates. Consecutively started cases were chosen - 90 patients with a design incorporating a labial bow (CTB group) and 110 with upper incisor 'torquing' spurs (STB group) and used to calculate failure rates. Thirty consecutive patients with satisfactory records from each group were analysed cephalometrically. The STB group experienced substantially less upper incisor retroclination, reduced upper incisor extrusion and slightly more favourable mandibular growth. The labial movement of lower incisors and the patient compliance were not significantly different in the two groups. Overall, 82.5% of patients fully reduced their overjet with 9% failing to reduce the overjet below 6 mm.Fig. 1f

Soft tissue profile changes in patients with cleft lip and palate following maxillary osteotomies.

OBJECTIVE: To investigate the soft tissue profile changes associated with Le Fort maxillary osteotomy in subjects with cleft lip and palate and the predictability of those changes. DESIGN: A retrospective cephalometric study. The sample comprises 28 patients with cleft lip and palate. All consecutively treated cases with satisfactory records at Frenchay Hospital, Bristol, and St. Lawrence Hospital, Chepstow, were included. RESULTS: Males and females showed no significant differences in their soft tissue response. The proportion of soft to hard tissue change increased progressively for points that are more inferiorly placed on the upper soft tissue profile. The horizontal change in upper incisor position was the most common significant predictor of soft tissue change but accounted for less than 50% of the variability of change for all soft tissue points. The cleft lip patients in this study did not have upper lips that were compressed as a result of the orthognathic surgery by a significantly different amount when compared with those of noncleft patients in previous studies. CONCLUSIONS: The soft tissue response to Le Fort osteotomy is similar in amount in cleft and noncleft subjects. Movement of the upper incisor tip is the best predictor of soft tissue changes, but the confidence limits of predictability are relatively wide.

The effect of extraction of third molars on late lower incisor crowding: a randomized controlled trial.

The problem of late mandibular incisor crowding is a well established phenomenon, the cause of which has been the substance of considerable debate over the years. A central issue is the possible role of the third molars though no definitive conclusions have been consistently drawn. This prospective study was designed to investigate the effects of randomly assigned early extraction of third molars on late crowding of the mandibular incisors. One-hundred-and-sixty-four patients entered the study from 1984 following completion of retention after orthodontic treatment. Seventy-seven patients (47%) returned for records up to a mean of 66 months later, and their start and finish study casts were digitized on a reflex microscope to determine Little's index of irregularity, intercanine width and arch length. Forty-four of the patients had been randomized to have third molars removed. There was no evidence of responder bias. Where third molars were extracted the mean increase in lower labial segment irregularity was reduced by 1.1 mm from a mean of 2.1 mm for the group where third molars were retained (P = 0.15, not statistically significant). This difference was also not considered to be clinically significant. The principal conclusion drawn from this randomized prospective study is that the removal of third molars to reduce or prevent late incisor crowding cannot be justified.

The clinical use of Activa self-ligating brackets.

The advantages and disadvantages of Activa self-ligating brackets ("A" Company, San Diego, Calif.) are discussed in the light of extensive clinical experience and the currently available data concerning frictional forces between arch wires and these brackets. Detailed practical recommendations are made concerning the problems that are encountered. The principal clinical advantages arise from the unusual combination of very low friction and excellent control of arch wire engagement. The potential benefits are the rapid alignment of very irregular teeth, lower anchorage requirements, and facilitation of sliding mechanics. Several problems arise from the unfamiliarity of a bracket without tie-wings, but the most significant drawback is the bond failure rate which is currently higher than with conventional brackets from the same manufacturer.

Bilateral root-resorption of upper first permanent molars.

Root-resorption of first permanent molars by impacted premolars is generally considered to be rare, although a few cases have been reported. A case is presented, of bilateral root-resorption of upper first permanent molars by unerupted second premolars, and a number of clinical conclusions are discussed.

A sectional approach to the alignment of ectopic maxillary canines.

A sectional fixed appliance is described for the alignment of ectopic maxillary canines. This system has a number of advantages over conventionally employed mechanics. These include both good aesthetics and optimal tooth alignment.

Screw fixation after mandibular sagittal split osteotomy: an intra-oral approach.

Intra-oral, rigid, non-compressive fixation was used in a feasibility study in 10 consecutive sagittal split osteotomies using two 3.5 or 2.7 mm diameter AO screws on each side. Seven patients were prognathic, three were retrognathic, and two had severe mandibular asymmetry. Lower third molars were removed concurrently in three patients. Horizontal and vertical stability was assessed by means of repeated, digitised cephalometry before operation, at 24-48 h and at 6 months. Intermaxillary fixation (IMF) was necessary during the first 48 h in one patient where the lingual fragments were too small. Intermaxillary elastics were used later in three patients. This method was straightforward, reliable, required no skin incisions and stability was similar to that following the use of transbuccal screw fixation. Mean horizontal relapse at 6 months (0.6 mm; maximum: 1.5 mm) was 8% of operative movement. Unsatisfactory occlusion (anterior open bite) necessitated removal of screws at 28 days in one patient. This was carried out intra-orally under local anaesthesia. These results suggest that stable, screw fixation for sagittal split osteotomies can be achieved without recourse to an external approach.

Changes in the complexity of orthodontic treatment for patients referred to a teaching hospital.

The records of 200 orthodontic patients accepted for treatment by the Orthodontic Department of the Bristol Dental Hospital in 1977 were compared with 200 taken on in 1985 in order to determine whether there had been any change in the proportion of referred cases requiring more complex procedures. Within each sample, cases were categorized as follows: (a) suitable for removable appliance treatment by an undergraduate or general practitioner; (b) requiring simple one arch fixed appliance treatment such as might be attempted by a general practitioner after a period of further training; (c) needing specialist treatment such as full multibracketed fixed appliances or orthognathic surgery. It was found that there had been no change in the proportions of simple and complex cases referred during the 8-year period although the proportion of patients now receiving complex treatment had increased greatly. Possible explanations and implications are discussed.

Computerized prediction of the results of orthognathic surgery.

Methods of visually and numerically predicting the results of orthognathic treatment are reviewed. The use of a computer program written by the authors and employing computer graphics for orthognathic prediction is described and illustrated. Suggested advantages and disadvantages of such a method are discussed.

Lip and mentalis activity and its influence on incisor position--a quantitative electromyographic study.

In order to investigate both the relationship between perioral muscular activity and tooth position and also the clinical indicators of this activity, two quantitative EMG studies were carried out. The first investigated the reproducibility of the method in 16 adults. Subsequently, a study employing the same protocol was conducted on 41 subjects with untreated malocclusions. Activity was measured during speech, whilst chewing biscuit, swallowing saliva, resting, and in those subjects with incompetent lips, during lip-seal. In addition to the EMG recordings, measurements were taken from study models, lateral skull radiographs and of the clinical lip heights. In general between visits random variability was sufficiently small for the method to be applied experimentally. The results suggest that the effects of perioral muscular activity are determined by the presence or absence of competent lips. This was despite similar levels of activity in both groups except during chewing. Resting activity did influence incisor position in subjects with competent lips but the intermittent activity from chewing, speaking and swallowing, did not. No clinical indicators of the level of perioral activity were found.