RECOMMENDATIONS FOR USE AND SCORING OF ORAL HEALTH IMPACT PROFILE VERSIONS.

BACKGROUND: OHIP's original seven-domain structure does not fit empirical data, but a psychometrically sound and clinically more plausible structure with the four OHRQoL dimensions Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact has emerged. Consequently, use and scoring of available OHIP versions need to be revisited. AIM: We assessed how well the overall construct OHRQoL and its four dimensions were measured with several OHIP versions (20, 19, 14, and 5 items) to derive recommendations which instruments should be used and how to score them. METHODS: Data came from the "Dimensions of OHRQoL Project" and used the project's learning sample (5,173 prosthodontic patients and general population subjects with 49-item OHIP data). We computed correlations among OHIP versions' summary scores. Correlations between OHRQoL dimensions, on one hand, and OHIP versions' domain scores or OHIP-5's items, on the other hand, were also computed. OHIP use and scoring recommendations were derived for psychometrically solid but also practical OHRQoL assessment. RESULTS: Summary scores of 5-, 14-, 19- and 49-item versions correlated highly (r = 0.91-0.98), suggesting similar OHRQoL construct measurement across versions. The OHRQoL dimensions Oral Function, Orofacial Pain, Orofacial Appearance, and Psychosocial Impact were best measured by the OHIP domain scores for Physical Disability, Physical Pain, Psychological Discomfort, and Handicap, respectively. CONCLUSION: Recommendations were derived which OHIP should be preferably used and how OHIP versions should be scored to capture the overall construct and the dimensions of OHRQoL. Psychometrically solid and practical OHRQoL assessment in all settings across all oral health conditions can be achieved with the 5-item OHIP.

The impact of premature birth on the mandibular cortical bone of children.

SUMMARY: Children born prematurely often have reduced skeletal mineralization. The aim in this study was to compare the cortical thickness of the lower jaw on radiographs of 8- to 10-year-old children with histories of preterm or full term births. There were no significant differences in cortical thickness between full term and preterm children at this age. INTRODUCTION: The purpose of this study was to compare the cortical thickness of the mandible on panoramic radiographs of 8- to 10-year-old children with histories of preterm or full term births. METHODS: Panoramic radiography was performed on 36 extremely preterm, 38 very preterm and 42 full term children at the age of 8 to 10 years. Five observers independently measured the mandibular cortical width on the panoramic radiographs at four defined sites bilaterally. Altogether, 928 sites were available. Measurements were performed twice on a random 24% of the sites by four observers. One-way analysis of variance with Tukey's post hoc test was used to test differences between groups. Intraclass correlation coefficient (ICC) was calculated for interobserver agreement while intra-observer agreement was expressed as measurement precision. RESULTS: Significant differences of mandibular cortical width were found between extremely preterm and very preterm children for five of the eight measurement sites with the very preterm showing the highest value. No significant differences were found between full term and either very preterm or extremely preterm except for one measurement site, with the extremely preterm showing the lowest value. ICC varied between 0.30 and 0.83 for the different sites (mean 0.62). The precision of a single measurement varied between 0.11 and 0.45 mm (mean 0.25 mm). CONCLUSIONS: From the evidence that very preterm children had significantly thicker mandibular cortices than extremely preterm children, we suggest that these findings may reflect the effect of mineral supplementation provided to premature infants, causing a 'shifting up' of bone mineral status relative to the full term peer group while maintaining the difference between very preterm and extremely preterm born children.

A randomized controlled trial of three orthodontic retention methods in Class I four premolar extraction cases -- stability after 2 years in retention.

OBJECTIVE: To evaluate three different retention methods in compliant patients after 2 years of retention. DESIGN: Three group randomized controlled trial. MATERIALS AND METHODS: The sample was recruited from patients having their fixed appliance treatment between 2001 and 2007. Seventy-five patients (45 girls and 30 boys with a mean age of 14.4 years at start of retention) were randomized into three retention methods: vacuum-formed retainer in the maxilla and bonded canine-to-canine retainer in the mandible (Group V-CTC), vacuum-formed retainer in the maxilla combined with stripping of the 10 proximal surfaces of the lower mandibular anterior teeth (Group V-S) and prefabricated positioner covering the teeth in the maxilla and the mandible (Group P). The following linear measurements were performed: Little's irregularity index (LII), intercanine width, intermolar width, arch length, overjet, overbite and body height growth. Registrations were made before orthodontic treatment, at start of retention, after 12 and finally 24 months in retention. Differences in means between groups were tested by one-way analysis of variance (SPSS). RESULTS: After 2 years all three retention methods were successful in retaining orthodontic treatment results. The major part of relapse took place during the 1st year of retention. CONCLUSIONS: All 3 types of retention methods were equally effective in controlling relapse to a clinically acceptable level.

TMD before and after correction of dentofacial deformities by orthodontic and orthognathic treatment.

The aims of the study were to investigate the alteration of temporomandibular disorders (TMD) after correction of dentofacial deformities by orthodontic treatment in conjunction with orthognathic surgery; and to compare the frequency of TMD in patients with dentofacial deformities with an age and gender matched control group. TMD were evaluated in 121 consecutive patients (treatment group), referred for orthognathic surgery, by a questionnaire and a clinical examination. 18 months after treatment, 81% of the patients completed a follow-up examination. The control group comprised 56 age and gender matched subjects, of whom 68% presented for follow-up examination. TMD were diagnosed according to research diagnostic criteria for TMD. At baseline examination, the treatment group had a higher frequency of myofascial pain (P=.035) and arthralgia (P=.040) than the control group. At follow-up, the frequencies of myofascial pain, arthralgia and disc displacement had decreased in the treatment group (P=.050, P=.004, P=.041, respectively). The frequency of TMD was comparable in the two groups at follow-up. Patients with dentofacial deformities, corrected by orthodontic treatment in conjunction with orthognathic surgery, seem to have a positive treatment outcome in respect of TMD pain.

The structure of observed learning outcome (SOLO) taxonomy: a model to promote dental students' learning.

Selective memorising of isolated facts or reproducing what is thought to be required - the surface approach to learning - is not the desired outcome for a dental student or a dentist in practice. The preferred outcome is a deep approach as defined by an intention to seek understanding, develop expertise and relate information and knowledge into a coherent whole. The aim of this study was to investigate whether the structure of observed learning outcome (SOLO) taxonomy could be used as a model to assist and promote the dental students to develop a deep approach to learning assessed as learning outcomes in a summative assessment. Thirty-two students, participating in course eight in 2007 at the Faculty of Odontology at Malmö University, were introduced to the SOLO taxonomy and constituted the test group. The control group consisted of 35 students participating in course eight in 2006. The effect of the introduction was measured by evaluating responses to a question in the summative assessment by using the SOLO taxonomy. The evaluators consisted of two teachers who performed the assessment of learning outcomes independently and separately on the coded material. The SOLO taxonomy as a model for learning was found to improve the quality of learning. Compared to the control group significantly more strings and structured relations between these strings were present in the test group after the SOLO taxonomy had been introduced (P < 0.01, one tailed test for both results). The SOLO taxonomy is recommended as a model for promoting and developing a deeper approach to learning in dentistry.

Evaluation of orthodontic treatment after 1 year of retention--a randomized controlled trial.

The aim of this study was to use a randomized controlled trial methodology to evaluate and compare three different retention methods. The capacity of the retention methods to retain orthodontic treatment results was in this first phase analysed on a short-term basis, i.e. after 1 year of retention. The subjects were recruited from adolescents undergoing fixed appliance treatment at an orthodontic clinic in the National Health Service (NHS) in Sweden between 2001 and 2007. Seventy-five patients (45 girls and 30 boys with a mean age of 14.4 years at the start of retention) were randomized into three retention systems; a vacuum-formed retainer in the maxilla and bonded canine-to-canine retainer in the mandible (group V-CTC), a vacuum-formed retainer in the maxilla combined with stripping of the 10 proximal surfaces of the lower mandibular anterior teeth (group V-S), and a prefabricated positioner covering the teeth in the maxilla and mandible (group P). The main outcome measures were: Little's irregularity index (LII), intercanine and intermolar width, arch length, overjet, and overbite. Registrations were made before orthodontic treatment, when the fixed orthodontic appliance was removed, and after 12 months in retention. Differences in means between groups were tested by one-way analysis of variance. After 1 year of retention, no clinically significant difference in retention capacity was found between the three retention methods. Small but significant differences (P < 0.05) were observed between the V-CTC and V-S groups regarding mandibular canine width, mandibular arch length, and overbite. In group P, two patients failed to co-operate.

Reliability of a questionnaire assessing experiences of adolescents in orthodontic treatment.

OBJECTIVE: To evaluate the reliability of a questionnaire that assessed the expectations and experiences of adolescent patients about orthodontic treatment. MATERIALS AND METHODS: The study included two groups of patients: 30 consecutive patients (19 girls and 11 boys, mean age 14.6 years, SD 2.3 years) naïve to orthodontic treatment, and 30 consecutive adolescent patients (17 girls and 13 boys, mean age 15.1 years, SD 2.0 years) in active orthodontic treatment with fixed appliances in both jaws. A questionnaire comprising 46 items was developed, based upon focus group interviews and previous established questionnaires. The questionnaire covered the following domains: Treatment motivation; treatment expectations; pain and discomfort from teeth, jaws, and face; functional jaw impairment; and questionnaire validity. Internal consistency as well as temporal stability with the test-retest method was investigated. RESULTS: A majority of the questions exhibited acceptable test-retest reliability, and composite scores yielded excellent reliability for all domains. Internal consistency was acceptable and good face validity was found for all domains. CONCLUSION: The questionnaire can be recommended for use in the assessment of expectations and experiences of orthodontic treatment.

Long-term stability of orthodontic treatment and patient satisfaction. A systematic review.

OBJECTIVE: To evaluate morphologic stability and patient satisfaction at least 5 years after orthodontic treatment. MATERIALS AND METHODS: Published literature was searched through the PubMed and Cochrane Library electronic databases from 1966 to January 2005. The search was performed by an information specialist at the Swedish Council on Technology Assessment in Health Care. The inclusion criteria consisted of a follow-up period of at least 5 years postretention; randomized clinical trials, prospective or retrospective clinical controlled studies, and cohort studies; and orthodontic treatment including fixed or removable appliances, selective grinding, or extractions. Two reviewers extracted the data independently and also assessed the quality of the studies. RESULTS: The search strategy resulted in 1004 abstracts or full-text articles, of which 38 met the inclusion criteria. Treatment of crowding resulted in successful dental alignment. However, the mandibular arch length and width gradually decreased, and crowding of the lower anterior teeth reoccurred postretention. This condition was unpredictable at the individual level (limited evidence). Treatment of Angle Class II division 1 malocclusion with Herbst appliance normalized the occlusion. Relapse occurred but could not be predicted at the individual level (limited evidence). The scientific evidence was insufficient for conclusions on treatment of cross-bite, Angle Class III, open bite, and various other malocclusions as well as on patient satisfaction in a long-term perspective. CONCLUSIONS: This review has exposed the difficulties in drawing meaningful evidence-based conclusions often because of the inherent problems of retrospective and uncontrolled study design.

Orthodontic anchorage: a systematic review.

The aim of this systematic review was to examine, in an evidence-based way, what kind of orthodontic anchorage systems/applications are evaluated and their effectiveness. A literature survey from the Pub Med and Cochrane databases covering the period from January 1966 to December 2004 was performed. Randomized controlled trials (RCT), prospective and retrospective controlled studies, and clinical trials comparing at least two anchorage situations were included. Two reviewers selected and extracted the data independently and also assessed the quality of the retrieved studies. The search strategy resulted in 494 articles, of which 14 met the inclusion criteria. Two main anchorage situations were identified: anchorage of molars during space closure after premolar extractions and anchorage loss in the incisor or premolar region (or both) during molar distalization. Because of contradictory results and the vast heterogeneity in study methods, the scientific evidence was too weak to evaluate anchorage efficiency during space closure. Intraoral molar distalization leads to anchorage loss in various amounts depending on the choice of distalization unit. Most of the studies had serious problems with small sample size, confounding factors, lack of method error analysis, and no blinding in measurements. To obtain reliable scientific evidence, controlled RCT's with sufficient sample sizes are needed to determine which anchorage system is the most effective in the respective anchorage situation. Further studies should also consider patient acceptance and cost analysis as well as implants as anchorage.

A review of oral devices in the treatment of habitual snoring and obstructive sleep apnoea.

With recent interest in sleep apnoea, oral devices have been proposed and used increasingly to treat patients suffering from snoring and obstructive sleep apnoea (OSA). Numerous case reports have been published and studies have been carried out to determine the efficiency and mechanism of action as well as evaluate side effects, complications and costs of different oral devices in the treatment of habitual snoring and OSA. A summary of the scientific basis and current opinions regarding oral devices in the treatment of habitual snoring and obstructive sleep apnoea is presented in this article. The selection of papers was based on a computerised search of published clinical and associated studies identified by MEDLINE from 1980 to November 2000. Although there is not yet enough scientific evidence for the clinician to determine which appliance is most likely to improve symptoms for a given patient, it appears from the literature that dental devices may have a place in the treatment of habitual snoring and mild and moderate cases of OSA. However, most of the studies are case series, raising questions on validity, and few studies use appropriate control groups. The general opinion is that these patients should not be treated without a sleep study as the OSA must be diagnosed before beginning treatment with oral devices to identify patients at risk and to provide a baseline to establish the effectiveness of the treatment. The main advantages of oral devices is the relative simplicity of the treatment, its reversibility and cost-effectiveness, and the fact that they can be used as an alternate treatment in patients who are unable to tolerate nasal continuous positive airway pressure (nCPAP) or who are poor surgical risks. Side effects occur in a significant proportion of patients using the MAD. In most cases these are minor and their importance must be balanced against the efficacy of the MAD in treating snoring and OSA. n.

Craniomandibular status and function in patients with habitual snoring and obstructive sleep apnoea after nocturnal treatment with a mandibular advancement splint: a 2-year follow-up.

The aim of the investigation was to evaluate the status and function of the temporomandibular joint (TMJ) and masticatory system in patients with habitual snoring and obstructive apnoea after 2 years nocturnal treatment with a mandibular advancement splint. Thirty-two patients participated in the study, ranging from 43.0 to 79.8 years of age (mean 54.4 years, SD 8.78) at the start of treatment. All patients had been referred from the ENT department for treatment with a mandibular advancement splint. The acrylic splint advanced the mandible 50-70 per cent of maximal protrusion, opened 5 mm vertically, and was used 6-8 hours per night and 5-7 nights per week. Overjet, overbite, and molar relationship were measured on dental casts. The patients were asked to answer a questionnaire concerning symptoms of craniomandibular dysfunction (CMD). They were also clinically examined in a standardized manner, including registration of range of mandibular movements, TMJ sounds, pain on movement, and palpatory tenderness of the TMJ and the masticatory muscles. None of the patients showed more than five symptoms of dysfunction either at the start of or after 2 years of treatment. A decrease in the frequency of headache was found for nine of those 18 patients that reported headache (P = 0.004). A minor, but significant decrease in overjet and overbite was found and the molar relationship was also changed. It was concluded that 2 years' treatment with a mandibular advancement splint had no adverse effects on the craniomandibular status and function, but the observed occlusal changes requires further evaluation.

A comparative analysis of distal maxillary molar movement produced by a new lingual intra-arch Ni-Ti coil appliance and a magnetic appliance.

The aim of the study was to evaluate cephalometrically the dental and skeletal treatment effects of a new lingual intra-arch Ni-Ti coil appliance for molar distalization and to compare these with those of an established intra-arch appliance that uses repelling magnets for distal molar movement. Two groups of 21 adolescents, all girls, participated in this retrospective study. One group was treated with the new lingual Ni-Ti coil appliance for 6.5 months and the other with the magnetic appliance for 5.8 months. The treatment effects were analysed by measurements on lateral head radiographs at the start of treatment and after the molar distalization was completed. The mean amount of distal molar movement was 2.5 mm (SD 0.69) in the lingual coil group and 2.6 mm (SD 0.51) in the magnet group. A significantly higher degree of distal molar tipping was found in the magnet group, -8.8 degrees, compared with -2.2 degrees for the lingual coil group. Due to anchorage loss, the maxillary incisors moved forwards, and the overjet was increased by an average of 1.2 mm in the lingual coil group and 1.7 mm in the magnet group. The results indicate that the new lingual Ni-Ti coil appliance was better choice than the magnet appliance for distal bodily movement of maxillary molars. The benefits of the new Ni-Ti appliance were due to the design preventing molar tipping and its single activation.

Does 2 years' nocturnal treatment with a mandibular advancement splint in adult patients with snoring and OSAS cause a change in the posture of the mandible?

The aim of this pilot study was to investigate the effects of 2 years' nocturnal treatment with a mandibular advancement splint in adult patients with snoring and obstructive sleep apnea syndrome with respect to possible development of a forward position of the mandible or other dentofacial changes. Thirty snoring and sleep apnea patients, mean age 55.3 years (SD, 8.61; range, 46.5 to 79.8 years), referred from the Ear, Nose, and Throat Department, were treated with an acrylic splint with full tooth coverage that advanced the mandible 5 to 8 mm (70% of maximal protrusion) and used 5 mm opening vertically. The splint was used 6 to 8 hours per night and 5 to 7 nights per week. Two lateral head radiographs were taken in centric occlusion, 1 before and 1 after 2 years of treatment. A small but statistically significant forward and downward change in mandibular position was found after treatment; mean was 0.4 mm (SD, 0.53; range, 0.0 to 2.0 mm; P <.001) and 0.3 mm (SD, 0.43; range, 0. 0 to 1.5 mm; P <.001), respectively. The forward and downward movement of the mandible was accomplished by a statistically significant increase in mandibular length-mean was 0.4 mm (SD, 0.62; range, 0.0 to 2.5 mm; P <.01)-and a significant decrease in overjet (P <.001) and overbite (P <.05). However, none of the patients reported any permanent sense of altered occlusion, and the anteroposterior distance between habitual occlusion (intercuspal position) and centric relation (retruded position) did not exceed 1. 0 mm in any of the patients either before or after the treatment. The change in mandibular position might be a result of a condylar and/or glenoid fossa remodeling or condylar position changes within the fossa as a compensatory reaction to the advancement of the mandible (bite jumping). However, to visualize and analyze such possible changes in detail, additional studies using lateral tomography of the temporomandibular joints or magnetic resonance imaging are required. Furthermore, because the treatment of snoring and OSAS patients is considered to be lifelong, long-term studies are needed to analyze if the small change in mandibular position will continue with further treatment.

Long-term effects of orthodontic magnets on human buccal mucosa--a clinical, histological and immunohistochemical study.

The aim of this intra-individual study was to examine human buccal mucosa clinically, histologically and immunohistochemically after 9 months' exposure to orthodontic magnets. In each of eight subjects (17.8-42.4 years), a magnet and a demagnetized equivalent of parylene coated neodymium-iron-boron was bonded alternately on the left and right side, to the buccal surface of maxillary premolars. The buccal mucosa was clinically examined and photographed, and three punch biopsies (6 mm diameter) of the buccal mucosa were taken from each subject at the site of contact with the magnet (test), in contact with the demagnetized magnet (control), and also at a site on the control side without contact with the demagnetized magnet (normal). The biopsies were snap-frozen for histological and immunohistochemical investigation, using antibodies to PD7 (lymphocyte 'naive T'), UCHL 1 ('memory T'), HLADR, ELAM-1 and ICAM-1. Clinically, the buccal mucosa showed normal features before and after the experimental period. In four of the eight subjects, the epithelium was 1.4-2.3 times thicker in the control and test tissues than in normal tissues. The difference between controls and tests was negligible, and there were no signs of increased keratinization or other surface abnormalities. Compared with normal sites, all control and test sites showed slightly increased ELAM-1/ ICAM-1 vascular staining, accompanied in three subjects by small infiltrates of PD7/UCHL 1-positive lymphocytic cells and in all subjects by focal keratinocyte HLADR-staining. The minor tissue reactions found in test and control tissues were interpreted to be a result of microtrauma (contact irritation) and not caused by the static magnetic field per se, since there was no difference between test and control tissues.

Interdental bone changes after orthodontic treatment: a 5-year longitudinal study.

Two groups of 20 adolescents, one treated and one untreated, were followed longitudinally for 5 years. The interdental alveolar bone level was estimated as the distance between the cementoenamel junction and the alveolar bone crest on bite-wing radiographs of the upper and lower premolars and molars on three occasions, the first at the start of treatment, the second after 2.8 years, and the third at the end of the 5-year study period. Between the first and second examination, the subjects in the treatment group were orthodontically treated in the upper arch with magnets and superelastic coils succeeded by straight-wire appliances in both arches. At the start of this study, no significant difference in alveolar bone level between treated and untreated groups was found. It was demonstrated that there was a small but significant decrease in interdental alveolar bone support ranging between 0.1 and 0.5 mm during the 5-year observation period both in the treated and untreated group. Neither group had any sites with clinically significant bone loss, i.e., a distance > 2 mm between the cementoenamel junction and the alveolar bone crest. The treated group exhibited a statistically significantly larger increase of cementoenamel junction and the alveolar bone crest distance at the mesial surfaces of the first and second maxillary molars than did the untreated group. This was thought to be a direct consequence of the orthodontic treatment, either as a result of band placement, tipping, or extrusive effects, or due to tooth morphology leading to plaque accumulation.

Class II correction with magnets and superelastic coils followed by straight-wire mechanotherapy. Occlusal changes during and after dental therapy.

The investigation comprised 18 consecutively selected patients, mean age 14.7 years at the start of treatment, with Class II malocclusion, deep overbite and space deficiency in the maxillary arch. The first phase of the treatment consisted of 6 months simultaneous distal movement of maxillary first and second molars with repelling samarium-cobalt magnets on one side and a superelastic nickel-titanium coil on the contralateral side together with an anterior biteplane to achieve bite opening. For the second phase of the treatment, a straight-wire appliance was used for an average treatment time of 1.3 years. Lateral head radiographs and dental casts were available at the start of treatment, after molar distalisation, at the end of treatment and 1 year post-treatment. The treatment resulted mainly in dental changes. The dental Class II molar relation was corrected to Class I by bodily distal movement of maxillary molars and by mesial movement of the mandibular molars. The correction of molar relation was significantly greater on coil sides than on magnet sides, mean 3.4 mm, and 3.0 mm, respectively. Despite anchorage loss associated with the maxillary molar movement, i.e. mesial movement of the maxillary incisors (mean 1.8 mm), the net overjet was reduced, mean 2.5 mm, by the use of Class II elastics. The average net improvement of bite opening was 2.6 mm, mainly due to extrusion of mandibular and maxillary molars. During the 1-year post-treatment period no significant dental or skeletal changes were found. The long-term implications of the treatment results need further consideration.

A magnetic appliance for treatment of snoring patients with and without obstructive sleep apnea.

The aim of this intraindividual study was to investigate the effects of an intraoral magnetic appliance on snoring, daytime sleepiness, and blood oxygen saturation, as well as to analyze the effects on the craniomandibular complex and investigate the response of the device to craniofacial structure. Twenty-five male patients (mean age 54.1 years, SD 11.44) with handicapping snoring or obstructed sleep apnea (OSAS) participated in the study. The appliance consisted of a maxillary and a mandibular occlusal acrylic splint. In each splint, four cylindrical neodymium-iron-boron magnets were embedded and oriented to produce intermaxillary forces that pulled the mandible forward. After a treatment period of 6 months, questionnaires were used for registration of the patients' subjective rating of daytime sleepiness and their close relatives' opinions about the snoring. The treatment effects on the temporomandibular joint were evaluated, according to Helkimos' anamnestic and dysfunctional index, and nightly registration of blood oxygen saturation was performed before and after 6 months of treatment. The effects on craniofacial skeletal and soft tissue profiles were analyzed cephalometrically. All patients easily accepted the magnetic appliance. The main symptoms, snoring and daytime sleepiness, decreased significantly when the magnet appliance was inserted (p = 0.0001 and p = 0.0002, respectively). The blood oxygen saturation during sleep was also improved (p = 0.012). The treatment had no aberrant effects on the temporomandibular joint status. The appliance made the mandible rotate downward and backward, mean 7.8 degrees, and this rotation mostly camouflaged the forward movement of the mandible. There was no significant influence on the hyoid bone position, but the hypopharyngeal airway space increased, the tongue base was lowered, and the contact between the tongue and soft palate was reduced significantly.

Attractive magnets for orthodontic extrusion of crown-root fractured teeth.

A subgingival crown-root fracture presents the clinician with a difficult restorative problem, including reaching the fracture line, and is complicated by the need to maintain the periodontal tissues in good health. The treatment options up to now have usually been limited to extrusion of the remaining root with a conventional orthodontic appliance, surgical intraalveolar transplantation of the root or extraction with bridge replacement. In this report, a new method of orthodontic extrusion with attractive magnets is presented. One or two neodymium-iron-boron magnets were attached to the remaining root and a second, larger neodymium-iron-boron magnet was incorporated in a removable appliance. The roots were extruded 2 to 3 mm with a force range from 50 to 240 cN during a treatment period of 9 to 11 weeks. Good force control at short distances, no friction, and no material fatigue of permanent rare earth magnets resulted in successful rapid extrusion. No evidence of soft tissue dehiscences, aberrant tooth mobility, or root resorption was found.

Proximal alveolar bone level after orthodontic treatment with magnets, superelastic coils and straight-wire appliances.

Proximal alveolar bone level changes were radiographically determined in 20 subjects (mean age 14.3 years, SD 2.00) a short time after rapid orthodontic treatment with magnets and superelastic nickel-titanium coils succeeded by straight-wire appliances. The findings were compared with a matched control group of 20 individuals (mean age 14.3 years, SD 1.99) who had no history of orthodontic treatment. Proximal alveolar bone level changes were determined on bitewing radiographs as the distance between the cementoenamel junction (CEJ) and the alveolar bone crest (AC). The observation period was 2.7 years (SD 0.65) for the treatment group and 2.8 years (SD 0.65) for the control group. In the treatment group, a small mean increase of 0.2 mm (SD 0.29) in the CEJ-AC distance was found a short time after treatment. In the control group the increase in CEJ-AC distance was 0.1 mm. The difference between the groups was significant (P < 0.001). In the treatment group, sites in the maxilla showed significantly greater CEJ-AC distances than in the mandible (P < 0.001), 0.3 mm (SD 0.33) versus 0.1 mm (SD 0.24). The mesial sites of the maxillary first molars in the treatment group showed the highest average increase in distance between CEJ and AC, mean 0.5 mm (SD 0.33). Neither group had any sites with bone loss, i.e., CEJ-AC distance exceeding 2 mm. No significant difference was found in CEJ-AC distance between teeth moved with magnets succeeded by straight-wire appliances and teeth moved with superelastic coils succeeded by straight-wire appliances.

Extent and flux density of static magnetic fields generated by orthodontic samarium-cobalt magnets.

The aim of this study was to measure and to analyze the extent and flux density of static magnetic fields generated by commercially available samarium-cobalt magnets used in orthodontics. The flux density was measured with a gaussmeter and a Hall probe with the magnets mounted in clinically relevant positions, i.e., in attractive and in repelling positions and also in the single position. Furthermore, the flux density between new and clinically used and recycled magnets was compared. It was found that the maximum flux density was generated at the pole faces and that magnets in attractive positions produced the highest flux density (2.2 kG), followed by the single magnet (2.0 kG) and the repelling magnets (1.7 kG). The flux density decreased rapidly (exponentially) with increased distance from the magnets. The flux density was approximately the same or less than the flux density of the earth magnetism (0.3 to 0.7 G) 60 mm from the attractive magnets, 50 mm from the single magnets, and 35 mm from the repelling magnets. The difference in flux density between new and clinically used and recycled samarium-cobalt magnets was negligible. Thus, the static magnetic field exposure of surrounding tissues can be assumed to be low, and the conceivable risk of harmful biologic effects must be regarded as small and limited when the tested orthodontic magnets are used clinically.