Static mandibular condyle positions studied by MRI and condylar position indicator.

We compared mandibular condyle positions as determined by magnetic resonance imaging (MRI) and a mechanical device, the condylar position indicator (CPI). Both methods assessed 3 mandibular positions in 10 asymptomatic males and 10 asymptomatic females, aged 23 to 37 years, free from temporomandibular disorders: maximum intercuspation, bimanually manipulated centric relation, and the unguided neuromuscular position. Bite registrations were obtained for bimanual operator guidance and neuromuscular position. 3 T MRI scans of both temporomandibular joints produced 3D data of the most superior condylar points in all 3 mandibular positions. Using mounted plaster casts and the same bite registrations, an electronic CPI displayed 3D data of its condylar spheres in these positions. The results showed interclass correlation coefficients ranging from 0.03 to 0.66 (95% confidence intervals from 0 to 0.8) and significantly different condyle positions between both methods (p = 0.0012, p < 0.001). The implications of the study emphasize that condyle position is unpredictable and variable. Its exact knowledge requires radiological imaging and should not rely on CPI assessments.

Estimated functional space of centric condyle positions in temporomandibular joints of asymptomatic individuals using MRI.

Magnetic resonance imaging (MRI) studies on centric condyle positions lack 3D comparisons of guided and unguided methods, which are used for accomplishing centric relation reference positions. The purpose of this study was to describe the space, in which mandibular condyles are placed in vivo by dental intercuspation, Dawson's bimanual manipulation, and neuromuscular position. Twenty asymptomatic individuals aged 23 to 37 years underwent separate bite registrations using bimanual manipulation and the unguided neuromuscular technique. Subsequent 3-Tesla MRI scans of both temporomandibular joints yielded 3D data of the most superior condylar points at maximum intercuspation and both centric relation positions. We found concentric condyle positions in maximum intercuspation but considerable variation of condyle position after bimanual manipulation and neuromuscular technique. Their 95% predictive confidence ellipses overlapped substantially and created a space of reference positions. Its smallest volume averaged 2 mm3 for a minimal convex hull (95% confidence interval 1.1-3.2) and 3.5 mm3 for a minimal ellipsoid hull (95% confidence interval 1.8-5.4). Visualized in vivo by MRI, condyle positions at bimanual manipulation and neuromuscular position were not predictable and showed substantial variation in asymptomatic subjects. Clinicians should be aware of the functional space and its effect on dental intercuspation.

Geometric morphometrics of different malocclusions in lateral skull radiographs.

BACKGROUND: To evaluate the role of craniofacial shape in malocclusion by application of geometric morphometrics to a set of two-dimensional landmarks and semilandmarks obtained from lateral skull radiographs. METHODS: Cephalometric radiograph tracings of 88 untreated Caucasians (age range 7-39 years) were assigned to four groups according to their occlusion: neutrocclusion, distocclusion, mesiocclusion, and anterior open bite. The geometric morphometric shape analysis incorporated 66 landmarks and semilandmarks, which underwent generalized Procrustes analysis, between-groups principal component analysis, thin-plate spline deformation grid visualization, permutation tests, and receiver operating characteristic curves. RESULTS: The position and shape of the mandible contributed to differences between the distocclusion and mesiocclusion groups, whereas the maxillary shape showed less variation. The growth-related shape alteration during adolescence was most pronounced in the mesiocclusion group and least pronounced in the neutrocclusion group. The open bite group was associated with an altered orientation of the mandibular body and the maxilla,  showed the most hyperdivergent maxillomandibular pattern but was not an own skeletal entity. Despite clear differences in mean shape across the four groups, the individual distribution of craniofacial shape overlapped between the groups without discrete clusters. CONCLUSIONS: Craniofacial shape was clearly associated with dental malocclusion and showed considerable variation. Geometric morphometrics was a powerful research tool but for diagnosing individual malocclusion standard cephalometric measurements including overjet and overbite were equally or more efficient than geometric morphometric descriptors.

Effect of extracorporeal shockwave therapy (ESWT) on pulpal blood flow after orthodontic treatment: a randomized clinical trial.

OBJECTIVES: The effect of non-invasive extracorporeal shockwaves on pulpal blood flow in orthodontic patients who have undergone active treatment was investigated. MATERIALS AND METHODS: Seventy-two adult patients were enrolled in the clinical trial and allocated by block randomization to a treatment or a placebo group at a 1:1 ratio. The patients were required to be otherwise healthy. Blinding was performed for the subjects and the outcome assessor. The region of interest was the mandibular incisors and canines, which were vital, unrestored, and had experienced no trauma. The active treatment group received a single shockwave treatment with 1000 impulses at 0.19-0.23 mJ/mm(2) while the placebo group was treated with a deactivated shockwave applicator but acoustic sham. Pulpal blood flow was evaluated four times over a period of 6 months starting from the day of bracket removal, using a laser Doppler device. RESULTS: Thirty patients were evaluated in each group. Orthodontic patients who have undergone active treatment tend to have high levels of pulpal blood flow which decrease over a period of 6 months. Pulpal blood flow did not differ significantly over 6 months between the placebo and treatment group. Shockwave treatment was associated with no significant effect in respect of tooth type, age, sex, or mean blood pressure, and had no unintended pernicious effects. CONCLUSIONS: Extracorporeal shockwaves had no statistically significant effect on pulpal blood flow. Multiple applications of ESWT in a pathological setup may be needed in future studies to demonstrate significant differences. CLINICAL RELEVANCE: The absence of any adverse effects justifies further principal investigations of the use of shockwave treatment in the oral cavity.

Impact of extracorporeal shockwave therapy on tooth mobility in adult orthodontic patients: a randomized single-center placebo-controlled clinical trial.

AIM: This RCT investigated the effect of non-invasive extracorporeal shockwaves on tooth mobility in orthodontic patients after active treatment. MATERIALS AND METHODS: Seventy-two adult patients were included in the study. Immediately after active orthodontic treatment, patients were assigned to a treatment or a placebo group based on block randomization. The orthodontic patients were required to be otherwise healthy. The region of interest was the anterior portion of the mandible. The treatment group received a single shockwave treatment with 1000 impulses while the placebo group was treated with an acoustic sham. Tooth mobility was evaluated over a period of 6 months using a Periotest and manual testing. Pocket probing depths, bleeding on probing and the irregularity index were also assessed. RESULTS: Tooth mobility reduced significantly over 6 months in both groups, but shockwaves achieved significantly more rapid reduction on manual testing. Probing depth was significantly reduced while the irregularity index remained stable. Bleeding on probing was significantly reduced in the treatment group. No anti-inflammatory effect could be derived due to possible initial group differences. CONCLUSIONS: The mobility of teeth aligned by orthodontic treatment reduces over time. Shockwave treatment appeared to reduce tooth mobility more rapidly.

Impact of extracorporeal shock-wave therapy on the stability of temporary anchorage devices in adults: a single-center, randomized, placebo-controlled clinical trial.

INTRODUCTION: In this randomized, placebo-controlled clinical trial, we investigated the effect of noninvasive extracorporeal shock waves on the stability of temporary anchorage devices (TADs) under orthodontic loading. METHODS: Thirty adult orthodontic patients of the Bernhard Gottlieb University Clinic in Vienna, Austria, were enrolled in this clinical trial and allocated by block randomization (size, 4) in a 1:1 ratio to either the treatment or the placebo group. Randomization was performed with software, and the allocations were concealed in sealed envelopes. Eligibility criteria included healthy adult patients with mesially directed orthodontic movement of the mandibular second molar into the extraction site of the mandibular first molar. The fixed orthodontic devices included active superelastic coil springs (200 cN) and TADs in the mandibular alveolar bone. Blinding was performed for the subjects and the outcome assessor. The treatment group received 1 shock-wave application with 1000 impulses at 0.19 to 0.23 mJ per square millimeter in the region of the TADs. The placebo group was treated with a deactivated shock-wave applicator and acoustic sham. The TADs positions were evaluated at placement and after 4 months. The reliability and precision of the impression process of the TADs were evaluated in an in-vitro model. RESULTS: Thirteen participants finished the investigation successfully in the treatment group but only 12 finished in the placebo group because 1 TAD loosened. The difference of the total TAD displacement for the 4-month time period between the placebo and treatment groups was 0.17 ± 0.95 mm (95% CI: -0.96, 0.62). No statistically significant difference between the 2 groups was found when sex was evaluated. Primary stability of the TADs as measured by placement torque, amount of tooth movement, and age of the patients did not influence displacement of the TADs. The reliability and precision of TAD impressions were confirmed. No unintended pernicious effects occurred after shock-wave treatment during the study period. CONCLUSIONS: A single application of extracorporeal shock-wave treatment did not improve the stability of the TADs during orthodontic loading. Sufficient interradicular space should be provided to minimize the risk of periodontal and dental root defects. REGISTRATION: This trial was registered at https://clinicaltrials.gov. PROTOCOL: The protocol was published before trial commencement, NCT01695928. FUNDING: No funding or conflict of interest to be declared.

The impact of education on the perception of facial profile aesthetics and treatment need.

BACKGROUND: The purpose of this study was to evaluate the influence of education on the perception of various male and female Caucasian profiles with respect to attractiveness and treatment need. METHODS: Four hundred questionnaires were distributed among six groups of raters (nonacademic laymen, academic laymen, preclinical students, clinical students, orthodontists, and maxillofacial surgeons). Male and female profile images were altered digitally in the sagittal and vertical dimensions resulting in nine different male and female profiles. The raters had to assess the images according to attractiveness and treatment needs. RESULTS: Three hundred four questionnaires were completed in this study. Age and gender of the rater had no significant influence on the perception of profile attractiveness. The different groups of raters perceived the Class I normodivergent profiles as most attractive. Significant differences in the perception of attractiveness were seen between laymen, orthodontists, and maxillofacial surgeons. The orthodontists and maxillofacial surgeons reported treatment needs the most. The orthodontists were most sensitive in discerning profiles. CONCLUSION: Attractive male and female profiles are recognizable by any rater. Education seemed to have a significant influence on facial profile perception and recommendation for treatment need of unattractive profiles. Professionals should be aware of their judgment discrepancy to laymen. LEVEL OF EVIDENCE III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Influence of different conditioning methods on immediate and delayed dentin sealing.

STATEMENT OF PROBLEM: Data are needed to evaluate the effect of various conditioning methods on immediate and delayed dentin sealing. PURPOSE: The purpose of this study was to test bond strength and surface configuration of immediate and delayed dentin sealing surfaces after applying different surface conditioning methods. MATERIAL AND METHODS: A total of 96 premolars were allocated to the immediate and delayed groups. The groups differed in the timing of dentin sealing. The immediate-group specimens were sealed with a self-etching adhesive immediately after preparation. The delayed-group specimens were sealed before the final ceramic restoration bonding. Provisional restorations were cemented on immediate-group and delayed-group specimens for 1 week. Four conditioning methods were used: polishing with fluoride-free pumice paste, airborne-particle abrasion with silicoated aluminum oxide, glycin, or calcium carbonate. After 24-hour storage, the shear bond strength was tested. The fractured specimens were optically inspected with a stereomicroscope. An optical 3-dimensional surface analysis was performed for quantitative and qualitative evaluation. A 2-way ANOVA with post hoc Tukey honestly significant difference tests for significant effects was performed to investigate effects of the 2 factors, sealing and conditioning, and their interaction (α=.05). RESULTS: Two-way ANOVA found significant differences between the sealing and conditioning groups. The immediate group had significantly lower bond strengths than the delayed group. In all groups, surface polishing produced the highest bond strengths, and airborne-particle abrasion with calcium carbonate produced the lowest. Fracture analysis found more failures in the adhesive layers in the immediate groups and a prevalence of mixed failures in the delayed groups. The surface analysis found significant abrasion and roughness when airborne-particle abrasion with silicoated aluminum oxide was used for immediate and delayed dentin sealing surfaces. CONCLUSIONS: Polishing and airborne-particle abrasion with silicoated aluminum oxide or glycin are efficient methods in conditioning immediate and delayed dentin sealing surfaces. Airborne-particle abrasion with silicoated aluminum oxide leaves significant surface alterations on both types of surfaces.

Impact of extracorporeal shock wave therapy (ESWT) on orthodontic tooth movement-a randomized clinical trial.

OBJECTIVES: This randomized clinical trial investigated the effect of extracorporeal shock waves on the amount of orthodontic tooth movement and periodontal parameters. MATERIAL AND METHODS: Twenty-six adult orthodontic patients participated in this clinical trial; all of them receiving lower second molar mesially directed movement. The fixed orthodontic device included superelastic coil springs (200 cN) and miniscrews as temporary anchorage device. The active treatment group received a single shock wave treatment with 1,000 impulses in the region of tooth movement. The placebo group was treated with deactivated shock wave applicator with an acoustic sham. The study period lasted 4 months with a monthly data exploration. RESULTS: No statistically significant difference in posterior-anterior tooth movement between the treatment and placebo group was seen during observation period. Gender had no significant influence on tooth movement in either group. No significant difference occurred in mesio-distal tipping and rotation, but a significant difference (p = 0.035) in bucco-lingual tipping of the molars was found. Periodontal status of the patients (sulcus probing depth, gingival index) did not significantly differ in both groups. The plaque index showed a significant difference (p = 0.003). CONCLUSIONS: Single application of extracorporeal shock wave treatment was associated neither with a statistically significant acceleration of tooth movement nor with an altered periodontal status in vivo. CLINICAL RELEVANCE: Shock waves showed no harmful effects in the investigated area. Their clinical use for lithotripsy during orthodontic therapy might be permitted.

Upper molar distalization with skeletally anchored TopJet appliance.

OBJECTIVE: To retrospectively investigate clinical outcomes with the TopJet appliance. MATERIALS AND METHODS: Measurements were taken on dental casts reflecting situations in 15 patients aged 10-48 years before and after orthodontic treatment with a TopJet appliance. Each measurement was taken with a digital caliper and repeated 2 weeks later. Recorded parameters included the amounts of distalization achieved, durations of active treatment to calculate rates of tooth movement, as well as rotational and transversal changes involved in the distalization of upper first molars. Student's t-test was used to compare mean values (α=0.05), explorative analysis to distinguish between unilateral and bilateral use of TopJet appliances, and Pearsons's correlation coefficient to determine intraobserver variability. RESULTS: Over a mean treatment duration of 5.9 months, the upper first molars were distalized by 4.0 ± 2.2 mm, including a mean tooth movement rate of 0.8 ± 0.6 mm per month. The rotational changes involved in the movements (-1.4 ± 6.7°) were not statistically significant. Transversal changes were 0.9 ± 1.2 mm at the level of the mesiobuccal cusps, 1.1 ± 1.1 mm at the central fossae, and 0.9 ± 0.9 mm at the distobuccal cusps. All measurements, other than those for rotation (r=0.7), were highly reproducible. Bilateral use of the appliance resulted in greater distalization than unilateral use, the mean difference being 1.4 mm. Bilateral use was more likely to involve inward rotation (+2.0°) on the mesial aspect of the first molars, whereas unilateral use resulted in mild outward rotation (-0.5°). CONCLUSION: Our results indicate that upper molars can be distalized effectively and efficiently with TopJet appliances. Any degrees of rotation and transversal changes that the first molars undergo during this process do not seem to play a major role.

Color stability of different composite resin materials.

STATEMENT OF PROBLEM: Data are needed to better predict the color stability of current composite resin materials. PURPOSE: The purpose of this study was to evaluate the impact of different storage solutions on the color stability of different composite resin materials. MATERIAL AND METHODS: Different restorative and adhesive composite resin specimens (dual-polymerizing self-adhesive resin cement, autopolymerizing resin-based composite resin, dual-polymerizing resin-based composite resin, nanohybrid composite resin, and microhybrid composite resin) were fabricated and stored in red wine, black tea, chlorhexidine, sodium fluoride, tea tree oil, or distilled water for 4 weeks at 37°C. Color parameters were measured with a colorimeter before and after storage. Total color differences and specific coordinate differences were expressed as ΔE, ΔL, Δa, and Δb. A 2-way and 1-way analysis of variance (ANOVA) with Bonferroni adjustment for multiple comparisons were applied for statistical calculations (α=.05). RESULTS: Red wine caused the most severe discoloration (ΔE >10), followed by black tea with perceptible (ΔE >2.6) to clinically unacceptable discoloration (ΔE >5.5). Colored mouth rinses discolored the materials to a lesser extent with clinically acceptable values. Dual-polymerizing resin adhesives showed a higher amount of discoloration. CONCLUSIONS: Current restorative and adhesive composite resin materials discolor over time under the influence of different storage solutions. The composition related to the polymerizing mode seemed to be a causative factor.

Rebonding performance of different ceramic brackets conditioned with a new silane coupling agent.

The objective of this study was to investigate the rebonding effect of a new silane coupling agent on various ceramic brackets bonded to ceramic specimen. Different ceramic brackets (Fascination 2, Clarity SL, and In-OvationC) were assigned to three groups: rebonding with new silane coupling agent, rebonding with conventional silane coupling agent, or regular bonding as control (n = 16). Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was evaluated using the adhesive remnant index score. One-way analysis of variance was applied for inferential statistics. Rebonding with the new silane coupling agent resulted in high shear bond strengths (SBSs; mean values: 37.44-41.24 MPa) and ceramic specimen fractures. Rebonding with the conventional silane coupling agent resulted in significantly (P < 0.001) lower clinically adequate SBS (mean values: 20.20-29.92 MPa) with the least ceramic specimen fractures. Regularly bonded ceramic brackets resulted in clinically adequate to high SBS (mean values: 17.06-41.56 MPa) depending on their bracket base design. Rebonded ceramic brackets showed sufficient SBS to ceramic specimen surfaces. However, increased bracket adhesion was associated with a risk of ceramic specimen surface damage. Therefore, ceramic brackets rebonded with the new silane coupling should be debonded cautiously using alternative debonding methods.

Comparison of Japanese and European overbite depth indicator and antero-posterior dysplasia indicator values.

This study evaluated cephalometric differences between 113 Japanese (43 males and 70 females, aged 14.1 ± 5 years) and 106 European subjects (36 males and 70 females, aged 13.5 ± 7.3 years) using two compound angular measurements and their single components: the overbite depth indicator (ODI) for the assessment of vertical skeletal relationships and the antero-posterior dysplasia indicator (APDI) for an evaluation of sagittal dysgnathia. Both populations were assigned to groups representing Angle Classes I, II, and III, and an anterior open bite (AOB) group. Two sample t- and Wilcoxon signed-ranks tests were performed (P < 0.05). The ODI values showed no statistically significant differences between the Japanese and European samples. The Japanese sample showed a significantly smaller APDI but only in the Class II group. In the Japanese Class II and III subjects, the malocclusion patterns were more pronounced than those in the Caucasian sample (overbite, overjet, and APDI).

Influence of surface conditioning on ceramic microstructure and bracket adhesion.

The objective of this study was to investigate the influence of different conditioning procedures on various ceramic microstructures and bracket adhesion. Ceramic specimens (feldspathic, leucite, leucite-free, and fluorapatite) were mechanically conditioned (n = 20 per ceramic type) with conventional hydrofluoric acid (5 per cent HF; 60/30 seconds), buffered hydrofluoric acid (9.6 per cent BHF; 60/30 seconds), or sandblasting (Al(2)O(3)/SiO(2) particles). Silane coupling agents were added for chemical conditioning before bracket bonding. Bracket adhesion was calculated with a shear test in a universal testing machine. The bracket-composite-ceramic interface was further evaluated using the adhesive remnant index (ARI). One specimen of each ceramic/conditioning combination was subjected to qualitative electron microscopy investigation. One-way analysis of variance followed by Tukey's honestly significant difference test were applied for inferential statistics. Conditioning with conventional 5 per cent HF or sandblasting resulted in significantly (P < 0.001) higher bond strengths (mean values: 34.11 and 32.86 MPa, respectively) than with 9.6 per cent BHF (mean value: 12.49 MPa). Etching time or sandblasting particles had no statistical (P > 0.001) influence on bond strength. Higher ARI scores were found in the conventional 5 per cent HF and sandblasted groups, when compared with the 9.6 per cent BHF group. Microscopic examination of the conditioned ceramic surfaces showed that leucite and leucite-free ceramics differed most with respect to their surface roughness, though without an influence on shear bond strength (SBS; P < 0.001). Bracket adhesion was mostly influenced by the conditioning procedure itself. Sandblasted ceramic surfaces showed sufficient conditioning and bracket adhesion; however, the increased bracket adhesion was associated with a risk of ceramic surface damage.

Left/right asymmetries and open/closed differences of interdental forces in the mandible.

The aim of the present investigation was to study the variation in interdental forces between mandibular canines and lateral incisors of 19 volunteers (9 males and 10 females) aged 20-26 years for four configurations (mandible open/closed and left/right side). These forces were derived by pulling a stainless steel matrix strip between these teeth, six times per configuration, and registering the time variation with a high-resolution transducer. The repeated median smoothing algorithm was applied to find the maximum of each curve and a bootstrap method estimated the 95 per cent confidence intervals (CIs) for all 76 configurations. Seventy-six per cent of all paired force differences were found to be significant. Asymmetry phenomena were observed: the interdental forces differed significantly between the left and right sides and also between the open and closed position of the mandible. The interdental forces (4-21 N) showed a pattern modulated by volunteer-specific features: in 91 per cent of the configurations, the interdental forces were larger when the mouth was open. This observed pattern contributes to the instability observed in clinical practice, thus necessitating permanent fixed lower retainer wear.

Shear bond strength of fluoride-releasing orthodontic bonding and composite materials.

Several fluoride-releasing bonding materials are available for orthodontic bracket placement. These are supposed to prevent white spot lesions during therapy. The objectives of this in vitro study were to evaluate the shear bond strength (SBS) and failure mode of a recently introduced fluoride-releasing adhesive, as well as the comparison with established orthodontic adhesives. Sixty bovine mandibular incisors were randomly allocated to three groups (n = 20): stainless steel brackets were bonded with Transbond Plus Color Change Adhesive, Transbond XT, or Light Bond. A universal testing machine was used to determine the SBS at a crosshead speed of 1 mm/minute. After debonding, the adhesive remnant index (ARI) was used to assess the adhesive remaining on the brackets. One-way analysis of variance comparing the three experimental groups showed no differences between the bonding systems for mean SBS (P = 0.27). ARI scores showed more residual adhesive on the teeth bonded with the Transbond systems (P < 0.01). As the fluoride-releasing bonding system provided sufficient mean bond strength in vitro (19.9 MPa), it may be used as an additional prophylactic measure in orthodontic therapy. However, the clinical effectiveness of its fluoride release may be questionable, as the amount of fluoride required from a bonding material to be caries preventive is still unknown.

Effects of rapid maxillary expansion on the airways and ears--a pilot study.

The aim of this prospective study was to describe the morphological and functional changes of the upper airways and the middle ears after rapid maxillary expansion (RME). Thirteen patients comprised the original study sample, of these three patients dropped out. Of the remaining 10 subjects, seven (two females, five males; average age, 8.7 years) underwent orthodontic RME with a Hyrax screw and three (one female, two males; average age, 8.3 years) served as the controls. Inclusion criteria for the study group were a uni- or bilateral crossbite with the evidence of a maxillary deficiency. Exclusion criteria were acute or chronic respiratory disease, allergies, cleft lip and palate, or absence of adenoids. An ear, nose, and throat (ENT) examination, lateral cephalometry, anterior rhinomanometry, tympanometry, and posterior rhinoscopy were carried out for each child at baseline (E1) and after 6 months (E2). Descriptive statistics were calculated for all diagnostic variables and correlations between the study and control group were evaluated. Rhinomanometry showed a correlation (r=0.57) between the size of the nasal pharyngeal area and nasal airflow, but only at 150 daPa. The size of the adenoids measured on the lateral cephalograms was correlated with the endoscopic findings. The size of the adenoids remained the same after RME. Patients with maxillary constriction had the largest adenoids and showed a negative pressure in the middle ear. However, this was reduced after RME. The results suggest a possible impact of maxillary deficiency on otorhinological structures. RME may lead to otorhinological changes. Further interdisciplinary investigations are needed to corroborate these findings.

Secular trends in the European male facial skull from the Migration Period to the present: a cephalometric study.

Secular trends in the facial skull over three Central European samples spanning more than 13 centuries were examined. Data were 43 conventional cephalometric landmark points for samples dating from 680 to 830 AD (29 male Avars), from the mid-19th century (49 adult Hapsburg Monarchy males), and from the 20th century (54 living Austrian young adult males). Analyses by standard methods of geometric morphometrics demonstrated shape differences by data and by size, with a strong interaction of these with sample, in that group mean differences were different for small and large individuals (allometry is different from period to period). The oldest sample, from the Migration Period, exhibited allometric features that may possibly be Turkic. There are implications for the orthodontist interested in growth trends or growth predictions in ethnically mixed patient samples.

Cytotoxicity and shear bond strength of four orthodontic adhesive systems.

The objective of this study was to compare the cytotoxicity of four orthodontic bonding systems, Light Bond, Enlight, Concise, and Transbond, and to evaluate their shear bond strength (SBS). These orthodontic bonding materials were applied to metal brackets (Mini Diamond). Glass specimens were used as controls in all experiments. Only Concise was a chemically cured system, the other systems were light cured. The specimens were added to L-929 fibroblast cultures immediately after fabrication or after pre-incubation for 7 days. The incubation time was 72 hours and the cells were counted by flow cytometry. One hundred and fifty-seven freshly extracted human third molars were used for testing the SBS in a universal testing machine. Statistical significance was determined using analysis of variance followed by post hoc comparisons for multiple-level alpha control. Pairwise comparisons showed a significant difference only between Light Bond and Concise (P = 0.0126). The highest SBS was obtained with Light Bond (23.23 +/- 1.53 MPa) followed by Transbond (20.39 +/- 1.18 MPa) and Enlight, (20.32 +/- 1.06 MPa). Concise (17.87 +/- 1.04 MPa) showed the lowest SBS. The cytotoxicity of all light-cured systems for fresh specimens was comparable, whereas the chemically cured system, Concise, was significantly more cytotoxic. After 7 days of pre-incubation, all systems were significantly less cyotoxic than fresh specimens (P < 0.001). Brackets alone were not cytotoxic. All bonding systems showed a clinically satisfactory bond strength higher than 10 MPa, with the chemically cured system showing the lowest SBS.