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Survival of resin-bonded bridgework provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors.

OBJECTIVE: To analyse the clinical performance and factors influencing the survival of resin-bonded bridgework provided for hypodontia patients with missing maxillary lateral incisors, following orthodontic treatment to open, maintain or redistribute the missing tooth space. DESIGN: A retrospective analysis of patients treated at a single centre using case notes with all patients invited for review to corroborate findings. SETTING: Departments of Orthodontics, Child Dental Health and Restorative Dentistry, Newcastle upon Tyne Dental Hospital and School. SUBJECTS AND METHODS: Between 1989-2000, 59 suitable hypodontia patients were identified of whom 45 had complete records. For these patients 73 resin-bonded bridges (RBBs) were provided. Following invitation, 24 patients attended for a review appointment. The survival of the RBBs, grade of operator providing treatment, duration of post-orthodontic retention, the influence of design, presence of pontic contact in static and dynamic excursions, and the effect of habits were assessed. Life table, Kaplan-Meier and Cox regression analysis were carried out for the 73 RBBs with complete records. A separate analysis of the RBBs provided for patients who attended for the invited review did not show a higher failure rate than those patients who did not attend. Therefore both sets of data were combined. RESULTS: Of the 73 RBBs provided, 30 had debonded on at least one occasion (41.1%), six of these debonds were due to trauma (20%). The mean survival time of all the restorations was 59.3 months, with a median survival time of 59 months. Senior members of staff (Consultant, Senior Lecturer or Specialist Trainee) provided most restorations (n = 39) and achieved the highest mean survival of 72.6 months and median survival time of 100+ months. RBBs provided by junior staff and students had significantly lower survival times (p <0.05) compared with senior staff. Risk of failure was 3.9 times greater with junior staff and 2.5 times greater with students (p = 0.01 and p = 0.02, respectively). Analysis of all the other factors investigated showed no statistical difference in survival times or in hazard ratios. Analysis of fixed/fixed versus cantilevered bridges was limited by the number of fixed/fixed bridges (n = 11), and only two cantilevered bridges with multiple abutments were provided; both failed within one month. CONCLUSION: RBBs provided for post-orthodontic hypodontia patients with missing maxillary lateral incisors can for many patients be an acceptable and definitive restoration. Experienced staff achieved the best results, but why this should be was not explained by the individual factors analysed in this study.

Adolescent↗

Instrument sterilization in orthodontic offices.

1. Three different quaternary ammonium compound solutions remained bactericidal against specific vegetative bacteria in three orthodontic offices over a ten day working period. However, no spore formers or viruses were tested. 2. Bacterial contaminants were cultured on pliers and scalers at the chair at least once in each of three orthodontic offices sampled twice a day for ten working days. 3. Sampled chairside instruments wiped with an alcohol sponge only, between patients, were contaminated an excessive 32.5% of the time, too frequently to be seriously considered for routine disinfection of pliers. 4. Chairside instruments, sampled regardless of other means of disinfection or sterilization used, were contaminated from 3.5 to 15% of the time. Therefore, storage and handling of orthodontic instruments must be evaluated and upgraded to prevent recontamination of previously sterilized instruments. 5. Staff personnel need courses in sterilization and disinfection procedures to prevent cross contamination from patient to patient and to protect themselves. These courses should be related specifically to orthodontic practice procedures.

Bacteria↗

Orthodontic treatment, dental health, and oral health behavior in young Norwegian adults.

Information about previous orthodontic treatment and oral health is evaluated for 525 17 yr-olds and 175 21 yr-olds. Of these, 24.6% of the 17 yr-olds and 14.3% of the 21 yr-olds had received orthodontic treatment. Orthodontic treatment did not appear to have had any adverse effect on the level of periodontal disease, and caries prevalence in the orthodontically treated 17 yr-olds was less than in the untreated subjects.

Adolescent↗

Communication in orthodontic treatment planning: bioethical and informed consent issues.

Orthodontic treatment planning is an interactive process in which the patient or parent and the orthodontist serve as co-decision makers. As in most partnerships, there is a natural tension between the orthodontist and the patient because of differences in their frames of reference. The orthodontist generally is influenced more by the objective findings (the problem list), whereas patients are guided more by subjective issues related to their perceived needs, desires, and values. The art of careful probing and listening to the patient as part of the treatment planning process is an essential skill. One of the most difficult situations in contemporary orthodontics is presented by the patient with a jaw discrepancy for which the alternative treatments are orthodontic camouflage through dental compensation or surgical-orthodontic correction. Computer imaging to simulate the probable treatment outcomes can facilitate communication about these alternatives by eliminating misconceptions. Full disclosure and the consideration of all viable treatment alternatives have great benefits from a risk management standpoint, in addition to their bioethical merits.

Adolescent↗

Changes in masseter muscle activity during orthodontic treatment evaluated by a 24-hour EMG system.

This study was conducted to investigate changes in masseter muscle activity during orthodontic treatment. Data was collected using a 24-hour electromyogram (EMG) system. Bursts of masseter muscle activity were counted over 24-hour periods approximately weekly before, during, and after an 18-month period of active orthodontic treatment. The patient, a 25-year-old male, was treated with a multibracket appliance. The number of bursts decreased substantially during the initial leveling period when the archwires were adjusted and then recovered to near the original preactivation level. No remarkable changes in masseter muscle activity were recorded during the latter half of treatment, although masseter muscle activity fell again when the appliance was removed. Six months after the end of treatment, relatively stable masseter muscle activity-similar to that recorded before treatment-was maintained. These changes in masseter muscle activity during orthodontic treatment were probably due to discomfort or pain or to changes in the occlusal relationship between the maxillary and mandibular dentitions produced by tooth movement or by the orthodontic appliance itself.

Adult↗

Corrosion of stainless steel, nickel-titanium, coated nickel-titanium, and titanium orthodontic wires.

Orthodontic wires containing nickel have been implicated in allergic reactions. The potential for orthodontic wires to cause allergic reactions is related to the pattern and mode of corrosion with subsequent release of metal ions, such as nickel, into the oral cavity. The purpose of this study was to determine if there is a significant difference in the corrosive potential of stainless steel, nickel titanium, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium orthodontic wires. At least two specimens of each wire were subjected to potentiostatic anodic dissolution in 0.9% NaCl solution with neutral pH at room temperature. Using a Wenking MP 95 potentiostat and an electrochemical corrosion cell, the breakdown potential of each wire was determined. Photographs were taken of the wire speci mens using a scanning electron microscope, and surface changes were qualitatively evaluated. The breakdown potentials of stainless steel, two nickel titanium wires, nitride-coated nickel titanium, epoxy-coated nickel titanium, and titanium were 400 mV, 300 mV, 750 mV, 300 mV, 1800 mV, and >2000 mV, respectively. SEM photographs revealed that some nickel titanium and stainless steel wires were susceptible to pitting and localized corrosion. The results indicate that corrosion occurred readily in stainless steel. Variability in breakdown potential of nickel titanium alloy wires differed across vendors' wires. The nitride coating did not affect the corrosion of the alloy, but epoxy coating decreased corrosion. Titanium wires and epoxy-coated nickel titanium wires exhibited the least corrosive potential. For patients allergic to nickel, the use of titanium or epoxy-coated wires during orthodontic treatment is recommended.

Coated Materials, Biocompatible↗

Bracket bond strength with transillumination of a light-activated orthodontic adhesive.

The literature describes transillumination as a means of curing orthodontic light-cured composite adhesive. The literature also recommends a 2 to 3 times increase in light exposure time when light curing using transillumination. The purpose of this study was to determine the transmittance of the curing light through human enamel and the effect of transillumination on the bond strength of orthodontic brackets. One hundred extracted human maxillary incisors were used in this study. Brackets with orthodontic composite adhesive were placed on the labial surface of the incisors and light cured from either the labial or the lingual (transillumination). The control sample was cured from the labial for a total of 40 seconds of light exposure. Experimental samples were cured from the lingual (transillumination) for 20, 30, 40, or 50 seconds. The shear-peel bond strengths were tested at 30 minutes and 24 hours after light application. The results of this study demonstrated no statistically significant difference between 40 seconds of labial curing and most of the lingually cured groups. The only experimental group that differed statistically from the control group was the 40-second lingual cure group tested at 30 minutes after light application. Actual bond strengths, however, were lower for all experimental samples. The samples tested at 24 hours that received 50 seconds of transillumination were nearly the same as the control values. This study demonstrated that transillumination of maxillary incisors is an acceptable method of curing orthodontic adhesive, particularly if the exposure time is increased from 40 to 50 seconds.

Analysis of Variance↗

Effect of using a new cyanoacrylate adhesive on the shear bond strength of orthodontic brackets.

During bonding of orthodontic brackets to enamel, conventional adhesive systems use three different agents: an enamel conditioner, a primer solution, and an adhesive resin. A unique characteristic of some new bonding systems is that they need neither a priming agent nor a curing light to bond brackets. Such an approach should be more cost-effective for the clinician and indirectly also for the patient. The purpose of this study was to determine the effects of using a cyanoacrylate adhesive on the shear bond strength of orthodontic brackets and on the bracket/adhesive failure mode. The brackets were bonded to extracted human teeth according to one of two protocols. Group 1: Teeth were etched with 37% phosphoric acid. After applying the primer, the brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif) and were light-cured for 20 seconds. Group 2: Teeth were etched with 35% phosphoric acid. The brackets were then bonded with Smartbond (Gestenco International, Göthenburg, Sweden). The present in vitro findings indicated that the use of the cyanoacrylate adhesive to bond orthodontic brackets to the enamel surface did not result in a significantly different (P = .24) shear bond force (mean = 5.8 +/- 2.4 MPa) as compared to the control group (mean = 5.2 +/- 2.9 MPa). The comparison of the Adhesive Remnant Index scores indicated that there was significantly (P = .006) less residual adhesive remaining on the tooth with the cyanoacrylate than on the tooth with the conventional adhesive system. In conclusion, the new adhesive has the potential to be used to bond orthodontic brackets while reducing the total bonding time.

Acid Etching, Dental↗

In vivo aging of orthodontic alloys: implications for corrosion potential, nickel release, and biocompatibility.

Despite the large number of studies investigating nickel release from orthodontic stainless steel and nickel-titanium alloys, there is a lack of conclusive evidence with respect to the composition and kinetics of the corrosive products released. The objective of this review is to address the critical issues of corrosion potential and nickel leaching from alloys by investigating the effect of intraoral conditions on the surface reactivity of the materials. After an overview of fundamentals of metallurgical structure of orthodontic alloys, we provide an analysis of corrosion processes occurring in vivo. We present recent evidence suggesting the formation of a proteinaceous biofilm on retrieved orthodontic materials that later undergoes calcification. We illustrate the vastly irrelevant surface structure of in vivo- vs in vitro-aged alloys and discuss the potential implications of this pattern in the reactivity of the materials. Finally, we present a comprehensive review of the issue of nickel release, based on three perspectives: its biologic effects, the methods used for studying its release, and nickel-induced hypersensitivity in orthodontic patients.

Corrosion↗

The effect of argon laser irradiation on demineralization resistance of human enamel adjacent to orthodontic brackets: an in vitro study.

Argon lasers, because of their significant timesavings over conventional curing lights, have been investigated for use in bonding orthodontic brackets. They are also being investigated for their ability to confer demineralization resistance on enamel, which is of great interest in orthodontics. A two-part in vitro study on 86 human posterior teeth was conducted to determine the effects of a five-second argon laser exposure on shear bond strength and to evaluate the effects of a five- and 10-second argon laser exposure (250 mW) on demineralization of enamel surrounding orthodontic brackets after exposure to an artificial caries bath. Brackets cured with the argon laser for five seconds yielded mean bond strengths similar to those attained with a 40-second conventional light-cured control (n = 13 per group, 20.4 vs 17.8 MPa). Brackets cured with the argon laser for 10 seconds resulted in significantly lower mean lesion depth when compared with a visible light control (n = 20 per group, 107.8 vs 137.2 microm, P = .038). There were no statistically significant differences in lesion depth between the five-second argon laser and the visible light control groups. Overall, there was a 15% and 22% reduction in lesion depths for the five- and 10-second group, respectively. Poor correlations were found between the clinical appearance of decalcifications and their lesion depth. Argon lasers used for bonding orthodontic brackets would save a significant amount of chair time while possibly conferring demineralization resistance upon the enamel.

Acetates↗

Relationship between signs and symptoms of temporomandibular disorders and orthodontic treatment: a cross-sectional study.

The aim of this study was to evaluate the prevalence of temporomandibular disorders (TMD) in individuals before and after orthodontic treatment. The sample comprised 200 individuals divided into four groups according to the type of malocclusion (class I or II) and the orthodontic treatment accomplished. An anamnestic questionnaire, comprising questions regarding the most frequent symptoms of TMD, was used to classify the sample according to the TMD presence and severity. A clinical examination, including TMJ and muscle palpation, mandibular range of motion, and joint noise analysis was performed. Based on the anamnestic questionnaire, 34% of the sample was considered as having mild TMD, whereas 3.5% had moderate TMD. A higher TMD prevalence was found in females. Joint noises (15.5%) followed by headache (13%) constituted the most frequent reported symptoms. The presence and severity of TMD have not shown any relationship with either the type of orthodontic mechanics or extraction protocols. On the other hand, a positive association was found between TMD and parafunctional habits and reported emotional tension. Orthodontic treatment is not associated with the presence of signs and symptoms of TMD.

Adolescent↗

An in vitro study simulating effects of daily diet and patient elastic band change compliance on orthodontic latex elastics.

This project investigated the effects of food exposure and patient compliance with elastic-band change on the degradation of forces in 3/16-inch, medium-wall, latex elastic bands during a simulated day of clinical wear. Six levels of daily diet/patient compliance were chosen as representative of orthodontic patients and a quasicontrol group. The groups differed with respect to how much exposure to artificial saliva and foodstuffs they experienced. After exposure in mild tension to daily diets and based on compliance with instructions about changing orthodontic elastics, the elastics were tested in tensile mode by stretching to 25 mm, where the load was recorded in newtons. The bands of three manufacturers, Rocky Mountain Orthodontics (RMO), 3M Unitek (UNO), and American Orthodontics (AMO), were examined, with 10 bands per group, per manufacturer, forming a cohort. Two-way analysis of variance and the Tukey-Kramer honestly significant difference tests were used to identify statistical significance (P > .05). With respect to bands from a single manufacturer, no differences were found between daily diet/patient compliance levels. However, differences (P < .0001) were found between manufacturers' bands. RMO > UNO > AMO in all environments. Over a 24-hour period, latex elastics maintain their applied load in the simulated oral environments.

Adolescent↗

Conventional and high-intensity halogen light effects on polymerization shrinkage of orthodontic adhesives.

The objectives of this study were to compare the polymerization shrinkage of three orthodontic adhesives. In addition we wanted to determine the effectiveness of the high-intensity quartz tungsten halogen (HQTH) in curing orthodontic adhesives on polymerization shrinkage with that of the quartz tungsten halogen (QTH). A total of 120 glass ring molds were prepared using a low-speed saw. The internal surface of the glass rings were roughened and etched. Adhesive pastes were placed into the glass molds, which were sandwiched between two glass slides. Samples were divided into six groups according to the combination of three orthodontic adhesives (Kurasper F, Light Bond, and Transbond XT) and two light intensities. One half of each 40 samples of three adhesive pastes was polymerized for 20 seconds by a QTH (Hilux 350), and the other half was polymerized for 10 seconds by a HQTH (Optilux 501). The volumetric polymerization shrinkage for each system was measured through the specific density method modified by Puckett and Smith. Statistical analysis was performed using two-way analysis of variance for intergroup comparisons. The HQTH-curing unit resulted in a more polymerization shrinkage than did the QTH for all investigated adhesives. However, no statistically significant differences were found. The highest shrinkage was observed for Light Bond cured with HQTH (1.59 +/- 0.82%), and the lowest value was observed for Transbond XT cured with QTH (1.23 +/- 0.60%). There are no significant differences in polymerization shrinkage of the three investigated orthodontic adhesives when polymerized with a QTH or a HQTH.

Acid Etching, Dental↗

Endodontic and orthodontic treatment of a cross-bite fused maxillary lateral incisor.

AIM: To describe combined endodontic and orthodontic treatment of a maxillary lateral incisor fused with a supernumerary. SUMMARY: A rare case is presented in which combined endodontic and orthodontic treatment was performed on a cross-bite fused tooth. Clinical and radiographic examination showed the maxillary lateral incisor fused with a supernumerary and an impacted canine. The fused tooth required nonsurgical and surgical endodontic treatment for functional and aesthetic reasons. The root canals were dressed with calcium hydroxide for 2 months before they were obturated with thermoplasticized injectable gutta-percha. Then, the distal part of the fused tooth was removed and the mesial part of the tooth was replanted and fixed. Three months after the completion of orthodontic therapy, the impacted canine erupted between the remaining tooth and the first premolar. Recall examination, 3 years after completion of root canal treatment, showed clinical and radiographic evidence of healing. KEY LEARNING POINTS: Fusion has been described as a development anomaly characterized by the union of two adjacent teeth. Proper combined endodontic and orthodontic treatment resulted in maintaining one tooth half and solving the aesthetic and functional problem of a fused tooth.

Child↗

Craniomandibular disorders and orthodontic treatment need in children.

Two hundred and forty subjects (113 boys and 127 girls), divided in three age groups, 7, 11, and 16 years were interviewed and clinically examined to estimate the prevalence of CMDs and the need for functional treatment, and to compare the functional status of the stomatognatic system in two subgroups: those judged to need orthodontic treatment and those judged not to need orthodontic treatment. Signs and symptoms of craniomandibular disorders were quite common and, in most cases, mild. There were significant differences in prevalence of CMDs between sexes. Only 3.7% of the patients were judged to need some functional treatment for CMDs. Trauma to the facial area and headaches were significantly associated with signs and symptoms of CMDs. No indication was found that oral parafunctions produce CMDs. No greater prevalence of CMDs signs and symptoms was found in subjects who needed orthodontic treatment than in subjects who did not need orthodontic treatment. In conclusion, preliminary results of this ongoing study support the contention that the high prevalence of signs and symptoms of CMDs is not really a measure of masticatory dysfunction, and that malocclusion does not appear to cause CMDs and/or to increase craniomandibular treatment need in a young population.

Adolescent↗

[The need for orthodontic treatment. Justification and methods of evaluation (part 1)].

Most adolescents in developing countries undergo orthodontic treatment. Three main reasons are routinely cited to justify the provision of orthodontic treatment i.e. the improvement of facial and/or dental aesthetic, the preservation of the health and functioning of the dentition. Orthodontic indices have been devised to minimise the subjectivity related to the classic orthodontic diagnosis. These indices can be classified under five headings: nosological, epidemiological, treatment need, outcome and complexity.

Adolescent↗

[Orthodontics based on a new scientific method of evaluating results: "evidence-based"].

In the orthodontic literature, randomized clinical trials are used to establish standards for the comparison of different clinical approaches. The balancing effect produced in a randomized study makes it possible to attribute the differences in results achieved clearly to treatment and not to variations in the biological characteristics of the patients involved. Recently, most randomized studies in orthodontics have been devoted to testing the hypothesis that some orthodontic appliances exert orthopedic effects that modify dento-facial growth. The authors propose definitions of "orthopedic effects" and of "dento-alveolar changes" and discuss the difficulties encountered in measuring them. They also review clinical studies published over the past 10 years on the correction of Class II malocclusions, on the problems of expansion and also report on Class IIl disorders. In addition they assess the problems associated with these clinical studies such as the ethical requirement of assuring that control groups receive treatment as appropriate for their maladies as that delivered to patients under study, the high cost of carrying them out, the relatively long delay before results can be evaluated, the difficulties of measuring all the different parameters involved, and the need to assemble large enough samples. To sum up, one can conclude that, because of all these impediments, randomized clinical studies have not as yet delivered the hope for benefit of collecting enough "evidence based" information for the orthodontic profession to deliver better treatment to its patients.

Cephalometry↗

Dentoalveolar distraction osteogenesis for rapid orthodontic canine retraction.

PURPOSE: We present a technique to reduce the overall orthodontic treatment time by means of dentoalveolar distraction osteogenesis. PATIENTS AND METHODS: Eleven patients who were planned to undergo orthodontic treatment with bilateral first premolar extractions and subsequent bilateral canine tooth distalization underwent osteotomy around the canine tooth. The first premolar was extracted, and the buccal bone was carefully removed. After wound closure, a special orthopedic device was mounted and cemented to the first molar and canine teeth. Distraction was started the same day at the rate of 0.4 mm twice a day and continued until adequate movement of the canine teeth was achieved. The device was then removed, and orthodontic therapy was continued with fixed appliances. RESULTS: The distraction rate and the device were well tolerated by all of patients. No anchorage loss in the second premolar and first molar teeth, root resorption, dental ankylosis, discoloration, or loss of vitality was detected. CONCLUSION: The concept of distraction osteogenesis for rapid orthodontic tooth movement is promising and feasible for clinical practice.

Adolescent↗