Effect of orthodontic management and orofacial muscle training protocols on the correction of myofunctional and myoskeletal problems in developing dentition. A systematic review and meta-analysis.

The aim of this review was to evaluate available evidence on the effect of early orthodontic management and myofunctional treatment in the developing dentition children, on anterior open bite correction, as well as on normalization of patterns of mouth breathing, swallowing and tongue resting position and pressure. Electronic searches in MEDLINE, Cochrane and LILACS, without language restrictions were conducted. Additionally, unpublished literature was identified. Randomized controlled trials, or controlled clinical trials, comparing interventions applied to manage anterior open bite and other muscle functions such as breathing/swallowing pattern and tongue resting position and pressure, were considered. Quality assessment was based on the Cochrane Risk of Bias tool. Random effects meta-analyses were conducted to assess treatment effects. From the 265 initial search results, 15 articles were included in the review. Eight were randomized controlled trials (RCTs) and 7 were controlled clinical trials. Treatment outcomes comprised skeletal and dentoalveolar changes recorded cephalometrically, mouth posture and lip closure normalization, improvement of tongue resting position/pressure and modification of swallowing pattern. Quantitative synthesis was possible for only 2 of the included RCTs. There was no evidence to support bonded lingual spurs over banded fixed appliances for the correction of anterior open bite in mixed dentition children presenting nonnutritive oral habits at the onset of treatment (SMD: -0.03; 95%CI: -.81, 0.74; P = 0.94). Although early orthodontic management and myofunctional treatment in the deciduous and mixed dentition children appears to be a promising approach, the quality of the existing evidence is questionable.

The effect of rheumatoid arthritis and functional loading on the structure of the mandibular condyle in a transgenic mouse model: An FTIR study.

OBJECTIVE: The objective of the present study was to investigate the effect of rheumatoid arthritis and functional loading through diet modification on the biochemical properties of the mandibular condyle in a transgenic mouse model and compare with healthy littermates. DESIGN: Twenty three, 4-week old hybrid male mice were used. Eleven were of transgenic line hTNF 197 (Tg 197 - with rheumatoid arthritis - RA) and 12 healthy littermates, both from mixed background CBAxC57BL/6. Four groups of mice were formed. Group 1 [n =5, RA-hard] included transgenic mice and received ordinary (hard) diet; group 2 [n=6, RA-soft] included transgenic line and received soft diet; group 3 [n=6, control-hard] were healthy littermates receiving ordinary (hard) diet and group 4 [n=6, control-soft] were healthy littermates with soft diet. Experimental period was 28 days. Following sacrifice, the mandibular condyles were subjected to micro-attenuated reflection Fourier transform infrared spectroscopy (micro-ATR FTIR) to reveal collagen/proteoglycan conformation of the condylar cartilage, while resin-embedded and metallographically polished specimens were evaluated through reflection FTIR microscopy to identify mineralization status of the corresponding condylar bone. RESULTS: The multivariable analysis revealed significantly lower a-helix to amide I percentage area ratio for the transgenic animals after adjusting for diet (ß=-4.29, 95% CIs: -8.52, -0.06; p=0.04). Mineral phase indices did not differ significantly between RA and control groups regardless the type of diet. CONCLUSIONS: Internal derangement of the anatomical structure with denaturation in the collagen structural components of the mandibular condyles of the RA animals was found, while no association with functional loading through diet modification was recorded.

Effect of the probiotic bacterium Lactobacillus reuteri on white spot lesion development in orthodontic patients.

BACKGROUND/OBJECTIVES: The purpose of the study is to evaluate the effect of daily intake of lozenges containing probiotic bacteria on white spot lesion (WSL) formation as well as on salivary lactobacilli (LB) and mutans streptococci (MS) counts, in patients undergoing orthodontic treatment with fixed appliances. MATERIALS/METHODS: A randomized double-blind placebo-controlled study design with two parallel arms was employed. Patients (n = 85, mean age 15.9 years) with maxillary braces on at least eight anterior teeth and a remaining treatment period of 7-24 months were finally enrolled and randomly allocated to a test or placebo group. Subjects in the test group were instructed to take one probiotic lozenge containing two strains of Lactobacillus reuteri once daily. An identical lozenge without active bacteria was used in the placebo group. Dental plaque, WSL, and salivary MS and LB levels were recorded at baseline and immediately after debonding. RESULTS: The groups were balanced at baseline. The mean duration of the intervention was 17 months and the total dropout rate was 10 per cent. There were no differences in the incidence of WSL between the groups at debonding. The patients had generally a neglected oral hygiene, both at baseline and at the follow-up. The levels of salivary LB were significantly reduced in both groups (P < 0.05) at the time of debonding compared with baseline, while no alterations of the MS counts were unveiled. LIMITATIONS: WSL were scored from photos that may not fully mirror the clinical situation. Chair-side tests estimate the counts of selected bacteria in saliva and do not reflect the entire microbiota. The invention was implemented approximately 6 months after the onset of the fixed appliances and some lesions may have been present at bonding. CONCLUSIONS/CLINICAL IMPLICATIONS: Daily intake of probiotic lozenges did not seem to affect the development of WSL during orthodontic treatment with fixed appliances.

Treatment outcomes after extraction and nonextraction treatment evaluated with the American Board of Orthodontics objective grading system.

INTRODUCTION: A controversy exists regarding better treatment outcomes when patients treated with extractions and without extractions are evaluated. The aims of this study were to use the American Board of Orthodontics objective grading system (ABO-OGS) to evaluate and compare treatment outcomes in extraction vs nonextraction Class I patients and to determine whether the treatment choice was a significant predictor of success according to the ABO examination. METHODS: Discriminant analysis was applied to a sample of 542 patients, and a borderline sample of 55 patients was obtained. Of these patients, 25 were treated with extractions and 30 without extraction of the 4 first premolars. Treatment results were then assessed using the 8 variables of the ABO-OGS. RESULTS: The total scores ranged from 11 to 41 (mean, 27.04; SD, 6.3) for the extraction group and from 16 to 44 (mean, 29.07; SD, 7.1) for the nonextraction group. The variable of buccolingual inclination had the highest scores in both groups (8.44 [SD, 3.3] for the extraction group; 8.90 [SD, 3.8] for the nonextraction group; mean difference, 0.46; 95% CI, -1.44, 2.37; P = 0.63). However, no statistically significant intergroup differences were found, either between the scores of the 8 ABO-OGS variables or between the total ABO-OGS scores. Regarding the success rates of the ABO examination, no significant difference was found between the 2 treatment groups (odds ratio, 2.55; 95% CI, 0.74, 0.85; P = 0.14). CONCLUSIONS: For a patient with a borderline Class I malocclusion, extraction and nonextraction treatment can achieve the same quality of results as assessed by the ABO-OGS. Additionally, in these Class I patients, the treatment modality (extraction or nonextraction) is not a significant predictor of passing the ABO examination.

The role of cellular senescence on the cyclic stretching-mediated activation of MAPK and ALP expression and activity in human periodontal ligament fibroblasts.

Mechanical loading is considered to be a major parameter of the periodontal ligament (PDL) remodeling and differentiation. However, the molecular mechanisms that translate these forces to cellular responses are not fully elucidated. Especially, although aging affects PDL homeostasis, the role of cellular senescence on the activation of signaling pathways in periodontal ligament fibroblasts (PDLF) in response to mechanical stimulation has not been studied yet. Here, we present evidence showing that cyclic mechanical stimulation activates ERK, JNK and p38 MAPK in young (early-passage) human PDLF, in a RhoK-dependent manner. This response was found to be independent of the substratum (i.e. fibronectin or collagen) on which these cells grow. Stretching up-regulates also c-fos, a classical cellular response to mechanical deformation. Inhibition of ERK and JNK reduces, while that of p38 enhances stress-mediated c-fos expression. In addition, cyclic stretching stimulates the expression and activity of alkaline phosphatase (ALP), an early marker of osteoblastic differentiation. We have recently shown that senescent human PDLF have a significantly decreased expression of ALP, linked to an inability towards osteoblastic differentiation. Here, we found that senescent PDLF are able to respond to cyclic mechanical stretching by activating ERK, JNK and p38 MAPK, with similar kinetics compared to young cells, and by up-regulating c-fos and ALP expression and activity. However, even after stimulation, ALP levels in senescent cells are still much lower compared to the basal levels of their young counterparts, suggesting that senescence impairs the differentiation of human PDLF when subjected to cyclic mechanical deformation.

Torque efficiency of different archwires in 0.018- and 0.022-inch conventional brackets.

OBJECTIVE: To compare the archwires inserted during the final stages of the orthodontic treatment with the generated moments at 0.018- and 0.022-inch brackets. MATERIALS AND METHODS: The same bracket type, in terms of prescription, was evaluated in both slot dimensions. The brackets were bonded on two identical maxillary acrylic resin models, and each model was mounted on the orthodontic measurement and simulation system. Ten 0.017 × 0.025-inch TMA and ten 0.017 × 0.025-inch stainless steel archwires were evaluated in the 0.018-inch brackets. In the 0.022-inch brackets, ten 0.019 × 0.025-inch TMA and ten 0.019 × 0.025-inch stainless steel archwires were measured. A 15° buccal root torque (+15°) and then a 15° palatal root torque (-15°) were gradually applied to the right central incisor bracket, and the moments were recorded at these positions. A t-test was conducted to compare the generated moments between wires within the 0.018- and 0.022-inch bracket groups separately. RESULTS: The 0.017 × 0.025-inch archwire in the 0.018-inch brackets generated mean moments of 9.25 Nmm and 14.2 Nmm for the TMA and stainless steel archwires, respectively. The measured moments in the 0.022-inch brackets with the 0.019 × 0.025-inch TMA and stainless steel archwires were 6.6 Nmm and 9.3 Nmm, respectively. CONCLUSION: The 0.017 × 0.025-inch stainless steel and ß-Ti archwires in the 0.018-inch slot generated higher moments than the 0.019 × 0.025-inch archwires because of lower torque play. This difference is exaggerated in steel archwires, in comparison with the ß-Ti, because of differences in stiffness. The differences of maximum moments between the archwires of the same cross-section but different alloys were statistically significant at both slot dimensions.

Retrieval analysis of immediately loaded orthodontic mini-implants: material and tissue characterization.

OBJECTIVE: To investigate the morphological and compositional alterations of retrieved orthodontic mini-implants and the type of adjacent bone, in relation to loading period and anatomical region. MATERIALS AND METHODS: Seventy orthodontic mini-implants (Aarhus: n = 35 and AbsoAnchor: n = 35) were placed in the maxilla and mandible of 33 orthodontic patients for anchorage purposes. All mini-implants were immediately loaded for a period specified by treatment plan. Fifty-nine mini-implants were retrieved (Aarhus: n = 29 and AbsoAnchor: n = 30) and examined by stereomicroscopy, reflection Fourier transform infrared microspectroscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Tissue samples adjacent to the implants were histologically examined to identify the bone type. RESULTS: Changes in surface finish, formation of biological integuments, and compositional alterations mainly due to adsorption of proteinaceous material (rich in C, O, N, OH, NH, CH2/CH3, amide I, II, and III, and CH-OH) were identified in all mini-implants. In some cases, mineralized fragments were identified (rich in Ca, P, and Ca-P). In 25 out of the 59 histological sections examined, woven and lamellar bone types were detected. In 12 sections, only woven bone was detected, whereas in the residual 22, only lamellar bone was identified. A significant correlation was found between histological result and loading time but not between histology and region. CONCLUSION: Morphological and elemental alterations were found for both types of mini-implant surfaces. An increase of the loading period increased the possibility of lamellar bone development around mini-implants.

Extraction decision and identification of treatment predictors in Class I malocclusions.

BACKGROUND: The extraction rate in orthodontics varies throughout the years. While the extraction decision is easily made or excluded in clear-cut cases, it still remains controversial what makes an orthodontist decide to extract in borderline cases. The aim of this retrospective study was to identify the percentage of extraction cases in a large group of Class I malocclusions and to clarify which variables contributed most to the extraction decision. METHODS: The sample consisted of 542 randomly selected records of Class I patients treated in a university graduate program and in five private orthodontic offices. Of these patients, 331 were female and 211 male. The mean age was 14.55 (standard deviation (SD) 5.36) for the non-extraction group and 14.52 (SD 4.86) for the extraction group. The extensive series of 32 linear and angular measurements derived from the cephalometric analysis and the dental casts, along with the variables of age and gender, fueled a stepwise discriminant analysis. RESULTS: The percentage of the patients treated with four first premolar extractions was 26.8%. The results showed that the variables of lower crowding, lower lip to E-plane, upper crowding, and overjet accounted most for the decision to extract at a very significant level (Sig. 0.000). The discriminant analysis assigned a classification power of 83.9% to the predictive model (p<0.0001). Fisher's linear discriminant functions provided a mathematical model, according to which any case can be classified into the adequate treatment group. CONCLUSIONS: In a large contemporary sample of 542 Class I patients, the extraction rate was 26.8%. The most important measurements when the orthodontist decides extractions in Class I cases are lower crowding, lower lip to E-plane, upper crowding, and overjet. In clinical orthodontic practice, the findings facilitate treatment by providing evidence-based treatment predictors for Class I malocclusions.

Senescent human periodontal ligament fibroblasts after replicative exhaustion or ionizing radiation have a decreased capacity towards osteoblastic differentiation.

Loss of teeth increases with age or after genotoxic treatments, like head and neck radiotherapy, due to periodontium breakdown. Periodontal ligament fibroblasts represent the main cell type in this tissue and are crucial for the maintenance of homeodynamics and for its regeneration. Here, we have studied the characteristics of human periodontal ligament fibroblasts (hPDLF) that became senescent after replicative exhaustion or after exposure to ionizing radiation, as well as their ability for osteoblastic differentiation. We found that senescent hPDLF express classical markers of senescence, as well as a catabolic phenotype, as shown by the decrease in collagen type I and the increase of MMP-2 expression. In addition, we observed a considerably decreased expression of the major transcription factor for osteoblastic differentiation, i.e. Runx2, a down-regulation which was found to be p53-dependent. In accordance to the above, senescent cells have a significantly decreased alkaline phosphatase gene expression and activity, as well as a reduced ability for osteoblastic differentiation, as found by Alizarin Red staining. Interestingly, cells from both type of senescence express similar characteristics, implying analogous functions in vivo. In conclusion, senescent hPDLF express a catabolic phenotype and express a significantly decreased ability towards an osteoblastic differentiation, thus probably affecting tissue development and integrity.

A comparative assessment of torque generated by lingual and conventional brackets.

The aim of this study was to assess the effect of bracket type on the labiopalatal moments generated by lingual and conventional brackets. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), In-Ovation L lingual brackets (DENTSPLY GAC), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on identical maxillary acrylic resin models with levelled and aligned teeth. Each model was mounted on the orthodontic measurement and simulation system and 10 0.0175 × 0.0175 TMA wires were used for each bracket type. The wire was ligated with elastomerics into the Incognito, STb, and conventional brackets and each measurement was repeated once after religation. A 15 degrees buccal root torque (+15 degrees) and then a 15 degrees palatal root torque (-15 degrees) were gradually applied to the right central incisor bracket. After each activation, the bracket returned to its initial position and the moments in the sagittal plane were recorded during these rotations of the bracket. One-way analysis of variance with post hoc multiple comparisons (Tukey test at 0.05 error rate) was conducted to assess the effect on bracket type on the generated moments. The magnitude of maximum moment at +15 degrees ranged 8.8, 8.2, 7.1, and 5.8 Nmm for the Incognito, STb, conventional Gemini, and the In-Ovation L brackets, respectively; similar values were recorded at -15 degrees: 8.6, 8.1, 7.0, and 5.7 Nmm, respectively. The recorded differences of maximum moments were statistically significant, except between the Incognito and STb brackets. Additionally, the torque angles were evaluated at which the crown torque fell well below the minimum levels of 5.0 Nmm, as well as the moment/torque ratio at the last part of the activation/deactivation curve, between 10 and 15 degrees. The lowest torque expression was observed at the self-ligating lingual brackets, followed by the conventional brackets. The Incognito and STb lingual brackets generated the highest moments.

Torque expression of 0.018 and 0.022 inch conventional brackets.

The aim of this study was to assess the effect of the moments generated with low- and high-torque brackets. Four different bracket prescription-slot combinations of the same bracket type (Mini Diamond® Twin) were evaluated: high-torque 0.018 and 0.022 inch and low-torque 0.018 and 0.022 inch. These brackets were bonded on identical maxillary acrylic resin models with levelled and aligned teeth and each model was mounted on the orthodontic measurement and simulation system (OMSS). Ten specimens of 0.017 × 0.025 inch and ten 0.019 × 0.025 inch stainless steel archwires (ORMCO) were evaluated in the low- and high-torque 0.018 inch and 0.022 inch brackets, respectively. The wires were ligated with elastomerics into the brackets and each measurement was repeated once after religation. Two-way analysis of variance and t-test were conducted to compare the generated moments between wires at low- and high-torque brackets separately. The maximum moment generated by the 0.017 × 0.025 inch stainless steel archwire in the 0.018 inch brackets at +15 degrees ranged from 14.33 and 12.95 Nmm for the high- and low-torque brackets, respectively. The measured torque in the 0.022 inch brackets with the 0.019 × 0.025 inch stainless steel archwire was 9.32 and 6.48 Nmm, respectively. The recorded differences of maximum moments between the high- and low-torque series were statistically significant. High-torque brackets produced higher moments compared with low-torque brackets. Additionally, in both high- and low-torque configurations, the thicker 0.019 × 0.025 inch steel archwire in the 0.022 inch slot system generated lower moments in comparison with the 0.017 × 0.025 inch steel archwire in the 0.018 inch slot system.

A comparative assessment of forces and moments generated by lingual and conventional brackets.

The aim of this study was to assess the effect of bracket type on the labiopalatal forces and moments generated in the sagittal plane. Incognito™ lingual brackets (3M Unitek), STb™ lingual brackets (Light Lingual System; ORMCO), and conventional 0.018 inch slot brackets (Gemini; 3M Unitek) were bonded on three identical maxillary acrylic resin models, with a palatally displaced right lateral incisor. The transfer trays for the indirect bonding of the lingual brackets were constructed in certified laboratories. Each model was mounted on the orthodontic measurement and simulation system and ten 0.013 inch CuNiTi wires were used for each bracket type. The wire was ligated with elastomerics and each measurement was repeated once after re-ligation. The labiopalatal forces and the moments in the sagittal plane were recorded on the right lateral incisor. One-way analysis of variance and post hoc Scheffe pairwise comparisons were used to assess the effect on bracket type on the generated forces and moments. The magnitude of forces ranged from 1.62, 1.27, and 1.81 N for the STb, conventional, and Incognito brackets, respectively; the corresponding moments were 2.01, 1.45, and 2.19 N mm, respectively. Bracket type was a significant predictor of the generated forces (P < 0.001) and moments (P < 0.001). The produced forces were different among all three bracket types, whereas the generated moments differed between conventional and lingual brackets but not between lingual brackets.

Distraction-like phenomena in maxillary bone due to application of orthodontic forces in ovariectomized rats.

BACKGROUND: Orthodontic forces may not only influence the dentoalveolar system, but also the adjacent and surrounding cortical bone. AIM: Since there is very limited information on this issue, we aimed to study the possible changes in maxillary cortical bone following the application of heavy orthodontic forces in mature normal and osteoporotic rats. MATERIALS AND METHODS: Twenty-four 6-month-old female rats were selected and divided into an ovariectomized group and a normal group. In both groups, the rats were subjected to a 60 grFNx01 orthodontic force on the upper right first molar for 14 days. RESULTS: In both groups, histological sections showed that the application of this force caused hypertrophy and fatigue failure of the cortical maxillary bone. The osteogenic reaction to distraction is expressed by the formation of subperiosteal callus on the outer bony side, resembling that seen in distracted bones. CONCLUSION: From this study we concluded that heavy experimental orthodontic forces in rats affect the maxillary cortical bone. The osteogenic reaction to these forces, expressed histologically by subperiosteal callus formation, is similar to that seen in distraction osteogenesis models.

Adhesion of Porphyromonas gingivalis and Biofilm Formation on Different Types of Orthodontic Brackets.

Objectives. To examine the interaction between Porphyromonas gingivalis and 3 different orthodontic brackets in vitro, focusing on the effect of an early salivary pellicle and other bacteria on the formation of biofilms. Material and Methods. Mono- and multi-species P. gingivalis biofilms were allowed to form in vitro, on 3 different bracket types (stainless steel, ceramic and plastic) with and without an early salivary pellicle. The brackets were anaerobically incubated for 3 days in Brain Heart Infusion Broth to form biofilms. Bacteria were quantified by trypsin treatment and enumeration of the total viable counts of bacteria recovered. Results. Saliva was found to significantly affect (P < 0.001) adhesion and biofilm formation of P. gingivalis, with higher numbers for the coated brackets. No significant effect was detected for the impact of the type of biofilm, although on stainless steel and plastic brackets there was a tendency for higher numbers of the pathogen in multi-species biofilms. Bracket material alone was not found to affect the number of bacteria. Conclusions. The salivary pellicle seems to facilitate the adhesion of P. gingivalis and biofilm formation on orthodontic brackets, while the material comprising the brackets does not significantly impact on the number of bacteria.

Morphological and structural characteristics of orthodontic mini-implants.

AIM: The purpose of this study was to investigate the geometric characteristics, composition, microstructure, and pullout strength of commercially available orthodontic mini-implants. MATERIAL AND METHODS: The mini-implants used were AbsoAnchor®, Dual-Top™ JA, Spider Screws® K1, and Vector-TAS™. The geometric features were measured by optical microscopy. Surface texture and elemental composition were examined by scanning electron microscopy and energy dispersive X-ray microanalysis. Surface 3D roughness was estimated by optical profilometry, and pullout strength measured in artificial bone blocks with two bone densities. RESULTS: The AbsoAnchor® showed the highest intra-osseous surface area, followed by the Dual-Top™, Spider Screw®, and Vector-TAS™. The mini-implants were composed of a Ti6Al4V alloy. The Vector-TAS™ had the highest oxygen and phosphorus content with the most homogeneous surface texture. No significant differences were detected in amplitude surface roughness parameters (Sa, Sz) between the implants. However, differences existed in hybrid (Sdr, Sds) and functional (Sci) parameters. AbsoAnchor® achieved the highest pullout strength, followed by the Dual-Top™, Spider Screw®, and Vector-TAS™, with highest values in the high density group. The intra-osseous surface area of mini-implants showed a positive correlation with pullout strength, especially in the high density group. CONCLUSION: All the mini-implants tested were made of Ti6Al4V alloy. Significant differences were found in the surface area of the threaded parts. The significant differences documented in 3D surface roughness parameters (hybrid and functional) and pullout strength may anticipate variations in their clinical performance.

Laboratory evaluation of modern plastic brackets.

The aim of the study was to evaluate some properties of modern orthodontic plastic brackets. Seven bracket brands [Aesthetik-Line (AL), Avalon (AV), Brillant (BR), Elegance (EL), OrthoFlex (OF), Silkon Plus (SL), and Spirit MB (SP)] were included in the study. The properties tested were chemical composition, base morphology, slot roughness, Vickers hardness (VH), and shear bond strength (SBS) with enamel.According to the results, the brackets were composed of polyurethane (AV and OF), polyoxymethylene (BR), and Ca-Al-silicate fibre glass-reinforced polycarbonate (AL, EL, SL, and SP). Metallic slots were composed of austenitic stainless steel (EL and SP) and Ag-Cu alloy (AV). The base morphology exhibited distinct designs, employing parallel retentive canals (AV, EL, and OF) or round-angled square protrusions with major retentive elements (AL, BR, and SP) or a combination of both (SL). The SP metallic slot demonstrated the lowest Sz values. No significant differences were found in VH among the brackets before water immersion (19.6-16.9 VH). After 12 weeks immersion, the brackets showed a significant hardness reduction (16.6-12.9 HV). SBS ranged between 111 and 193 N (8-14 MPa) for all brackets, except from SP (59 N/5 MPa). The predominant failure mode was mixed adhesive and cohesive. Most of the plastic brackets presented a base structure capable of adequate bonding to enamel, regardless of their differences in composition. Slot roughness showed differences among groups. All the brackets demonstrated plasticization after prolonged water storage.

Reporting of research quality characteristics of studies published in 6 major clinical dental specialty journals.

The objective of this article was to record reporting characteristics related to study quality of research published in major specialty dental journals with the highest impact factor (Journal of Endodontics, Journal of Oral and Maxillofacial Surgery, American Journal of Orthodontics and Dentofacial Orthopedics; Pediatric Dentistry, Journal of Clinical Periodontology, and International Journal of Prosthetic Dentistry). The included articles were classified into the following 3 broad subject categories: (1) cross-sectional (snap-shot), (2) observational, and (3) interventional. Multinomial logistic regression was conducted for effect estimation using the journal as the response and randomization, sample calculation, confounding discussed, multivariate analysis, effect measurement, and confidence intervals as the explanatory variables. The results showed that cross-sectional studies were the dominant design (55%), whereas observational investigations accounted for 13%, and interventions/clinical trials for 32%. Reporting on quality characteristics was low for all variables: random allocation (15%), sample size calculation (7%), confounding issues/possible confounders (38%), effect measurements (16%), and multivariate analysis (21%). Eighty-four percent of the published articles reported a statistically significant main finding and only 13% presented confidence intervals. The Journal of Clinical Periodontology showed the highest probability of including quality characteristics in reporting results among all dental journals.

Release of bisphenol-A from a light-cured adhesive bonded to lingual fixed retainers.

INTRODUCTION: Our aim was to quantitatively determine the bisphenol-A (BPA) released from a light-cured orthodontic adhesive used to bond lingual fixed retainers. METHODS: Eighteen recently extracted premolars, divided into 3 groups of 6 teeth each, were embedded in plaster in an arch shape. A light-cured adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) was bonded to a .0195-in, 3-strand heat-treated twist flex wire (Wildcat, GAC International, Bohemia, NY) adjusted to the lingual surface of the teeth, and the arches were immersed in doubled-distilled water for 10, 20, and 30 days. The concentration of BPA in the 3 eluents was investigated with gas chromatography-mass spectroscopy; all assays were performed in triplicate, and the results were averaged. RESULTS: Measurable amounts of BPA were identified for all groups, with the highest found in the immersion media of the 1-month groups (2.9 µg/L), whereas the control (tooth storage solution) had 0.16 µg/L. CONCLUSIONS: The BPA released from a light-cured adhesive used to bond lingual fixed retainers might be assigned to the application mode of the material that differs from conventional use. Further testing including estrogenicity assays will assess the potential estrogenic action of this application. Composite restorative resins should replace orthodontic adhesives that were not intended to function with their surfaces in the oral cavity; alternatively, canine-bonded fixed retainers might reduce the amount of adhesive used.

In-vitro assessment of the forces generated by lingual fixed retainers.

INTRODUCTION: The aim of this article was to assess the effect of wire adaptation on the lingual surfaces of mandibular anterior teeth with 3 types of lingual retainers on the development of vertical and labiolingual forces. METHODS: Ten retainers (canine to canine) were constructed from each of the following wires: Wildcat 0.0195-in heat-treated 3-strand twist-flex wire (GAC, Bohemia, NY); Penta-one 0.0215-in 6-strand as received; and Penta-one 0.0215-in 6-strand after heat treatment at 350°C for 4 minutes (both, Masel Orthodontics, Carlsbad, Calif). The retainers were bonded on each tooth of an acrylic resin model, and the model was installed in the Orthodontic Measurement and Simulation System. The vertical and labiolingual forces generated were measured for wire displacements up to 0.2 mm in 0.02-mm increments. RESULTS: Wire displacement of 0.2 mm exerted forces as high as 1 N on the teeth. In the vertical direction, the highest force levels were recorded for the as-received Penta-one 0.0215-in and the lowest from its heat-treated counterpart. In the horizontal plane, the as-received Penta-one 0.0215-in exerted the highest forces. CONCLUSIONS: The forces recorded from the lingual retainer wires during 0.2-mm simulated intrusion-extrusion and buccal-lingual movements might generate high forces that exceed 1 N and be large enough to produce unwanted tooth movement during retention. The only significant determinant of the generated forces was the amount of wire displacement and not the type of wire used in this study.

A comparative assessment of the forces and moments generated at the maxillary incisors between conventional and self-ligating brackets using a reverse curve of Spee NiTi archwire.

OBJECTIVES: To compare the intrusive forces and labio-palatal moments generated at the maxillary incisors by a 0.017 x 0.025 inch reverse curve NiTi wire using self-ligating and conventional brackets. METHODS: Ten 0.017 x 0.025 inch reverse curve NiTi archwires were used with each of the following 0.022 inch bracket systems: Titanium Ortho (Ormco/Sybron, CA, USA), In-Ovation R (GAC International, NY, USA) and Damon System 3MX (Ormco/Sybron, CA, USA). The wires were inserted on bracketed maxillary Frasaco models, with segmented maxillary incisors. Simulated intrusion from 0.0-1.0 mm was performed on the Orthodontic Measurement and Simulation System, which recorded the intrusive forces and the labio-palatal moments at 0.05 mm increments. The data were analysed with the ANOVA and Scheffe tests. RESULTS: The intrusive forces were significantly different between all bracket types. The highest force was recorded with the conventional Titanium Orthos brackets (8.2 N), followed by the Damon 3MX brackets (6.3 N) and the In-Ovation R brackets (5.5 N). The moments were found to be significantly different between the conventional and the self-ligating brackets, but not between the two types of self-ligating brackets. The highest moments were recorded with the self-ligating brackets (16.6-16.9 N/mm), followed by the conventional brackets (10.8 N/mm). CONCLUSIONS: The intrusive forces exerted on the maxillary incisors by a 0.017 x 0.025 inch reverse curve NiTi archwire during the final 1 mm of levelling are very high and beyond the necessary intrusive force level for these teeth. Lower intrusive forces, but higher labio-palatal moments, were recorded with the self-ligating brackets.