PATIENT-REPORTED OUTCOMES WHILE MANAGING OBSTRUCTIVE SLEEP APNEA WITH ORAL APPLIANCES: A SCOPING REVIEW.

OBJECTIVE: This scoping review aims to describe dental treatment-related patient-reported outcomes (dPROs) while using oral appliances (OAs) to manage obstructive sleep apnea (OSA) in children and adults. METHODS: Available literature that assessed dPROs in children and adults with OSA managed through OAs. Any clinical studies were included without restrictions of year or country. The results were analyzed and reported using narrative text and tables accompanying a descriptive summary. RESULTS: The searches identified 1718 citations, and of these, forty-five studies were finally included. A total of 3498 adults were included in all 42 primary studies included in this review, in which all the studies presented adults as participants. The dPROs assessed were quality of life (QoL), reported side effects after OA usage, patient satisfaction, and experience with treatment, and subjective perception of occlusal changes after treatment. CONCLUSION: This scoping review suggests that dPROs are mostly investigated as a secondary outcome from major studies exploring the effects of OAs on OSA severity, and often, dPROs are not well discussed or displayed on their report. As no risk of bias or certainty level assessment was completed, findings need to be carefully considered. Although in general terms management with OAs among adults with OSA does not seem to be uncomfortable or causing major problems to their lives, some mild discomfort and endured occlusal disturbances was reported in some studies. QoL seems to improve but consistent agreement was elusive. Data does not include experiences among those that dropped OA use. No data seems to exist about dPROs in children.

Stability determinants of bone-borne force-transmitting components in three RME hybrid expanders-an in vitro study.

BACKGROUND: The aim was to test which component [wire arm, connecting abutment attachment, and orthodontic mini-implant (OMI)] of the force-transmitting system (FTS) in the anterior palate of three commonly used hybrid expanders (HEs; WILMES-HE, LUDWIG-HE, and WINSAUER-HE) deforms under increasing load. MATERIALS AND METHODS: Crude single and double wire arms were tested individually. Non-opening of the maxillae halves was simulated in artificial bone blocks with single wire and double wire FTS specimens. OMIs were inserted 8mm and underwent 6mm of continuous static lateral loading. Deformation angles were measured (X-ray, n = 6) at 0, 3 and 6mm feed. OMIs and abutments were scan electron microscope (SEM) evaluated. RESULTS: After 1.0mm of loading, the single wire arm of all FTS deformed between 63.4 (16.5) N and 76.2 (18.4) N, and the double wire arm of reinforced FTS (wires positioned 'side by side') deformed after 1.0mm between 110.0 (18.4) N and 134.8 (22.3) N. The crude single wire resisted 89 (5.1) N until plastic deformation, whereas the crude double wire positioned 'on top of each other' resisted 438 (21.3) N. At 6mm loading, the reinforced WINSAUER-HE FTS withstood a maximum load of 320.9 (31.1) N and the reinforced LUDWIG-HE FTS 19% less, both under great deformation of double wires and OMIs. The screw-fixated WILMES-HE FTS abutment attachment (overlapping OMI head 34%) detached around 250N. The bonded WINSAUER-HE and LUDWIG-HE abutment attachments did not detach. Nor did the modified bonded plus the modified screw-fixated WILMES-HE abutment attachment when overlapping 100%. CONCLUSION: Early OMI and single wire arm deformation in HEs are crucial for unsuccessful RME in more mature maxillae. Double wire arms should be obligatory. OMIs with inner diameter greater 1.36mm are recommended. One hundred per cent overlapping abutment attachments do not detach.

Comparison of the superelasticity of different nickel-titanium orthodontic archwires and the loss of their properties by heat treatment.

The aim of this work is to describe and compare mechanical properties of eight widely used nickel-titanium orthodontic wires under uniform testing conditions and to determine the influence of the heat treatments on the loss of the superelasticity. Ten archwires from two batches from eight different manufacturers were evaluated. A three-point bending test was performed, in accordance with ISO 15841:2006, on 80 round nickel-titanium archwire segments of 0.016 inch. To obtain a load-deflection curve, the centre of each segment was deflected to 3.1 mm and then unloaded until force became zero. On the unloading curve, deflection at the end of the plateau and forces delivered at that point, and at 3, 2, 1 and 0.5 mm of deflection, were recorded. Plateau slopes were calculated from 3 and from 2 mm of deflection. Data obtained were statistically analysed to determine inter-brand, intra-brand and inter-batch differences (P < 0.05). The results show that at 2 mm of deflection, maximum differential force exerted among brands [Nitinol SuperElastic (1.999N)-Sentalloy M (1.001 N)] was 0.998 N (102 gf). The Nitinol SuperElastic plateau slope (0.353 N/mm) was the only one that was statistically different from 2 mm of deflection, as compared with the other brand values (0.129-0.155 N/mm). Damon Optimal Force described the gentlest slope from 3 mm of deflection (0.230 N/mm) and one of the longest plateaus. Titanol and Orthonol showed the most notable intra-brand differences, whereas inter-batch variability was significant for Nitinol (Henry Schein), Euro Ni-Ti and Orthonol. Superelasticity degree and exerted forces differed significantly among brands. Superelasticity of Nitinol SuperElastic was not observed, while Damon Optimal Force and Proclinic Ni-Ti Superelástico (G&H) showed the most superelastic curves. Intra-brand and inter-batch differences were observed in some brands. In all cases, the heat treatment at 600 °C produces precipitation in the matrix. The precipitates are rich in titanium and this fact produce changes in the chemical composition of the matrix and the loss of the superelasticity. At 400 °C these precipitates are not produced and the forces delivered by the wires are very similar with wires untreated.

Correlation between permanent tooth eruption pattern and the predominance of the motor function laterality.

OBJECTIVES: To asses whether dental eruption order can play a role in the early diagnosis of crossed laterality. STUDY DESIGN: Dental eruption pattern along with eye, ear, hand and foot lateralism were examined on 131 children between 6 to 8 years old from public schools from a multietnic population area of Barcelona city. Statistic methods (Statgraphics Plus 5.1 program) were used to evaluate data recollected. RESULTS: Only foot and dentition lateralities behave as independent variables regarding hand laterality. So dental eruption laterality (along with the foot one) would be one of the parameters more related to hand laterality given that dentition variable relationship is greater that the foot one. This suggests that tooth eruption could be more clinically relevant. Crossed laterality hand-foot is significantly more predominant in men (13%) than in women (1,6%). Meanwhile, the relationship between hand and dentition didn't show any influence of sex. CONCLUSIONS: Dental eruption order, can be used as a good parameter in the determination of the patient's laterality.

Design characteristics, primary stability and risk of fracture of orthodontic mini-implants: pilot scan electron microscope and mechanical studies.

OBJECTIVE: Orthodontic mini-implants (OMIs) are increasingly used in orthodontics but can fail for various reasons. This study investigates the effects of OMI design characteristics on the mechanical properties in artificial bone. MATERIAL AND METHODS: Twelve self-drilling OMIs (2 small, 6 medium, 4 large) from 8 manufacturers were tested for their primary stability in simulated medium-high cancellous bone and the risk to fracture in high-density methacrylate blocks. For the assessments of the maximum insertion torque (IT) and torsional fracture (TF) 5 of each OMI were used and for the pull-out strength (POS) 10. The OMIs were inserted with a torque screwdriver (12 sec/360°) until the bottom at 8 mm depth was reached. OMI designs were analyzed with a scan electron microscope (SEM). RESULTS: SEM images revealed a great variation in product refinement. In the whole sample, a cylindrical OMI shape was associated with higher POS (p<0.001) but lower IT (p=0.002) values. The outer and inner OMI diameters were design characteristics well correlated with POS, IT and TF values (ranging from 0.601 to 0.961). Greater thread depth was related to greater POS values (r= 0.628), although OMIs with similar POS values may have different IT values. Thread depth and pitch had some impact on POS. TF depended mainly on the OMI inner (r= 0.961) and outer diameters (r=0.892). A thread depth to outer diameter ratio close to 40% increased TF risk. CONCLUSION: Although at the same insertion depth the OMI outer and inner diameters are the most important factors for primary stability, other OMI design characteristics (cylindrical vs. conical, thread design) may significantly affect primary stability and torsional fracture. This needs to be considered when selecting the appropriate OMI for the desired orthodontic procedures.

Properties of Superelastic Nickel-Titanium Wires after Clinical Use.

The aim of the present study was to describe and determine changes in the superelastic properties of NiTi archwires after clinical use and sterilization. Ten archwires from five different manufacturers (GAC, 3M, ODS, GC, FOR) were cut into two segments and evaluated using a three-point bending test in accordance with ISO 14841:2006. The center of each segment was deflected to 3.1 mm and then unloaded to 0 N to obtain a load-deflection curve. Deflection at the end of the plateau and forces at 3, 2, 1 and 0.5 mm on the unloading curve were recorded. Plateau slopes were calculated at 2, 1 and 0.5 mm of deflection. Data obtained were statistically analyzed to determine differences (p < 0.001). Results showed that the degree of superelasticity and exerted forces differed significantly among brand groups. After three months of clinical use, FOR released a greater force for a longer activation period. GC, EURO and FOR archwires seemed to lose their mechanical properties. GC wires released more force than other brand wires after clinical use. Regarding superelasticity after sterilization, GAC, 3M and FOR wires recovered their properties, while EURO archwires lost more.

Enamel Evaluation after Debonding of Fixed Retention and Polishing Treatment with Three Different Methods.

Lack of standardization of the retention phase has led to many studies of stability of movements and characteristic of retainers, disregarding the enamel repercussions of fixed retention on this phase. This study aimed to analyze different methods of enamel polishing after detachment of orthodontic retainers. Forty-five healthy premolars were divided into three groups according to the polishing bur after debonding, and four specimens without intervention were used as control. A 0.038 × 0.015 inches gold chain was bonded between the premolars and then removed. The adhesive remnant was removed with three types of burs according to the study groups (Group 1: white stone at high speed; Group 2: high-speed handpiece with a 30-blade tungsten carbide bur; Group 3: low-speed handpiece and a 30-blade tungsten bur). After debonding and polishing, all samples were analyzed with a confocal microscopy on surface roughness parameters: Sa: Arithmetic mean of the height of the surface. Rq: Square mean of the height of the surface and Sz: Maximum surface height. Mechanical tests were carried out to determine the bonding stress of the retention adhered to the teeth using an electromechanical testing machine. The adhesion stress was 8.23 MPa (±0.87). The quality of the refinement of the enamel after debonding is essential in order to preserve its integrity. The use of the 30-blade tungsten carbide bur provides a smooth enamel surface after polishing.

Effect of Fluoride Content of Mouthwashes on the Metallic Ion Release in Different Orthodontics Archwires.

Metal ion release studies were carried out on three of the most commonly used orthodontic wires in the clinic: austenitic stainless steel, Ti-Mo, and superelastic NiTi, using three mouthwashes with different fluoride concentrations: 130, 200, and 380 ppm. Immersions were carried out in these mouthwashes at 37 °C for 1, 4, 7, and 14 days, and the ions released were determined by inductively coupled plasma-mass spectrometry (ICP-MS). All wires were observed by scanning electron microscopy (SEM). The results showed a moderate ion release in the stainless steel wires, with nickel and chromium values of 500 and 1000 ppb in the worst conditions for the wires: concentrations of 380 ppm fluoride and 14 days of immersion. However, in the Ti-Mo and NiTi alloys, an abrupt change in release was observed when the samples were immersed in 380 ppm fluoride concentrations. Titanium releases in Ti-Mo wires reached 200,000 ppb, creating numerous pits on the surface. Under the same conditions, the release of Ni and Ti ions from the superelastic wires also exceeded 220,000 ppb and 180,000 ppb, respectively. This release of ions causes variations in the chemical composition of the wires, causing the appearance of martensite plates in the austenitic matrix after 4 days of immersion. This fact causes it to lose its superelastic properties at a temperature of 37 °C. In the case of immersion in 380 ppm mouthwashes for more than 7 days, rich-nickel precipitates can be seen. These embrittle the wire and lose all tooth-correcting properties. It should be noted that the release of Ni ions can cause hypersensitivity in patients, particularly women. The results indicate that the use of mouthwashes with a high content of fluoride should not be recommended with orthodontic archwires.

Closing extraction spaces with lingual orthodontics.

There are different ways of closing extraction spaces with lingual orthodontics. One is to use loop mechanics and the other is to use sliding mechanics. This case report describes the treatment of closing spaces using sliding mechanics with and without the use of microscrews. Understanding and applying basic biomechanical principles is necessary for lingual orthodontics and the use of miniscrews. The purpose of this article is to demonstrate the effect of orthodontic miniscrews in controlling anchorage and the basic biomechanical considerations in understanding the influence of the anterior teeth.

The efficiency of molar distalization using clear aligners and mini-implants: Two clinical cases.

When using clear aligners, if distalization greater than 3mm is required, there is no real predictable procedure to follow. The aim of this article is to show with two clinical cases the biomechanics of distalizing lower molars with mini-implant anchorage and aligners.

Effect of Fluoride Content of Mouthwashes on Superelastic Properties of NiTi Orthodontic Archwires.

The influence of sodium fluoride (NaF) concentration in mouthwashes on the properties of superelastic NiTi orthodontic wires has been studied. In this work, 55.8%Ni and 44.2%Ti (in weight) wires were introduced in commercial mouthwashes with different NaF contents (0, 130, 200 and 380 ppm). The release of Ni2+ and Ti4+ ions was by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) at 1, 4, 7 and 14 days. Superelastic orthodontic wires present at oral temperature the austenitic phase which is transformed into a plastic phase (martensite) by cooling. The temperatures at which this occurs are influenced by the chemical composition. The release of ions from the wire will produce variations in the temperatures and stresses of the stress-induced martensitic transformation. Ms, Mf, As, Af were determined by Differential Scanning Calorimeter (DSC). The transformation stresses (austenite to stress induce martensite) were determined with a servo-hydraulic testing machine at 37 °C. The surfaces for the different times and mouthwash were observed by Scanning Electron Microscope (SEM). The release of Ni2+ in mouthwashes with 380 ppm NaF concentrations reaches 230,000 ppb in 14 days and for Ti4+ 175,000 ppb. When NaF concentrations are lower than 200 ppm the release of Ni and Ti ions is around 1500 ppb after 14 days. This variation in compositions leads to variations in Ms from 27 °C to 43.5 °C in the case of higher NaF concentration. The increasing immersion time and NaF concentrations produce a decrease of Ni in the wires, increasing Ms which exceed 37 °C with the loss of superelasticity. In the same way, the stresses (tooth position corrective) decrease from 270 MPa to 0 MPa due to the martensitic phase. The degradation can produce the growth of precipitates rich in Ti (Ti2Ni). These results are of great interest in the orthodontic clinic in order to avoid the loss of the therapeutic properties of superelastic NiTi due to long immersion in fluoride mouthwashes.

Bacteriostatic Poly Ethylene Glycol Plasma Coatings for Orthodontic Titanium Mini-Implants.

Titanium mini-implants are used as anchorage for orthodontic tooth movements. However, these implants present problems due to the infection of surrounding tissues. The aim of this work was to obtain a polyethylene glycol (PEG) layer by plasma in order to achieve a bacteriostatic surface. Titanium surfaces were activated by argon plasma and, after, by PEG plasma with different powers (100, 150 and 200 W) for 30 and 60 min. The roughness was determined by white light interferometer microscopy and the wettability was determined by the contact angle technique. Surface chemical compositions were characterized by X-ray photoelectron spectroscopy (XPS) and cytocompatibility and cell adhesion studies were performed with fibroblast (hFFs) and osteoblast (SAOS-2) cells. Bacterial cultures with Spectrococcus Sanguinis and Lactobacillus Salivarius were performed, and bacterial colonization was determined. The results showed that plasma treatments do not affect the roughness. Plasma makes the surfaces more hydrophilic by decreasing the contact angles from 64.2° for titanium to 5.2° for argon-activated titanium, with values ranging from 12° to 25° for the different PEG treatments. The plasma has two effects: the cleaning of the surface and the formation of the PEG layer. The biocompatibility results were, for all cases, higher than 80%. The polymerization treatment with PEG reduced the adhesion of hFFs from 7000 to 6000 and, for SAOS-2, from 14,000 to 6500, for pure titanium and those treated with PEG, respectively. Bacterial adhesion was also reduced from 600 to 300 CFU/mm2 for Spetrococcuns Sanguinis and from 10,000 to 900 CFU/mm2 for Lactobacillus Salivarius. The best bacteriostatic treatment corresponded to PEG at 100 W and 30 s. As a consequence, the PEG coating would significantly prevent the formation of bacterial biofilm on the surface of titanium mini-implants.

Relationship between the order of permanent tooth eruption and the predominance of motor function laterality: a cross-sectional study.

OBJECTIVES: To assess whether the order of permanent tooth eruption may be a useful indicator of motor function laterality. METHODS: We conducted a cross-sectional study in schoolchildren aged 6-8 years old evaluated in the annual school-based routine dental health examinations conducted by the staff of the primary care centre of an urban district in Barcelona, Spain. We also evaluated hand, foot, eye, and auditory lateralities using a battery of simple exercises. Bivariate and multivariate analysis of data was performed. RESULTS: The study sample included 388 children, 51.3% female, with a mean age of 6.5 years. Right laterality was the predominant side in every variable under study, especially in tooth eruption (310 children; 80%), handedness (349; 89.9%), and footedness (337; 86.8%). In the bivariate analysis, we found a statistically significant association of tooth eruption laterality with handedness and footedness, and of tooth eruption laterality with ocular and auditory lateralities (p<.001). In the multivariate analysis, tooth eruption laterality and foot laterality were independent variables significantly associated with hand laterality. The diagnostic accuracy of tooth eruption laterality and foot laterality in relation to hand laterality as reference, showed a similar sensitivity and positive and negative predictive values, but the specificity of dentition laterality was higher (79% versus 66%). CONCLUSIONS: Laterality in the order of dental eruption is a useful indicator of right or left motor function laterality in developing individuals that may be particularly helpful to determine the main dominance in cases of crossed laterality.

Potential impact of pediatric obstructive sleep apnea on mandibular cortical width dimensions.

STUDY OBJECTIVES: To analyze differences in mandibular cortical width (MCW) among children diagnosed with obstructive sleep apnea (OSA) or at high- or low-risk for OSA. METHODS: A total of 161 children were assessed: 60 children with polysomnographically diagnosed OSA, 56 children presenting symptoms suggestive of high-risk for OSA, and 45 children at low risk for OSA. Children at high- and low-risk for OSA were evaluated through the Pediatric Sleep Questionnaire. MCW was calculated using ImageJ software from panoramic radiograph images available from all participants. Differences between MCW measurements in the 3 groups were evaluated using analysis of covariance and Bonferroni post-hoc tests, with age as a covariate. The association between MCW and specific cephalometric variables was assessed through regression analysis. RESULTS: The participants' mean age was 9.6 ± 3.1 years (59% male and 41% female). The mean body mass index z-score was 0.62 ± 1.3. The polysomnographically diagnosed OSA group presented smaller MCW than the group at low-risk for OSA (mean difference = -0.385 mm, P = .001), but no difference with the group at high-risk for OSA (polysomnographically diagnosed OSA vs high-risk OSA: P = .085). In addition, the MCW in the group at high-risk for the OSA was significantly smaller than the group at low-risk for the OSA (mean difference = -0.301 mm, P = .014). The cephalometric variables (Sella-Nasion-A point angle (SNA) and Frankfort - Mandibular Plane angle (FMA)) explained only 8% of the variance in MCW. CONCLUSIONS: Reductions in MCW appear to be present among children with OSA or those at high-risk for OSA, suggesting potential interactions between mandibular bone development and/or homeostasis and pediatric OSA. CITATION: Fernandes Fagundes NC, d'Apuzzo F, Perillo L, et al. Potential impact of pediatric obstructive sleep apnea on mandibular cortical width dimensions. J Clin Sleep Med. 2021;17(8):1627-1634.

Comparison of changes in the dental transverse and sagittal planes between patients treated with self-ligating and with conventional brackets.

INTRODUCTION: Several advantages have been established regarding the efficiency of self-ligating brackets (SL). In spite of some controversy surrounding this question in the literature, clinical results confirm that "arch development" requires fewer extractions. OBJECTIVE: The objective of this study was to compare changes in the transverse and sagittal planes in patients treated with conventional ligating brackets (CL)as well as in patients treated with SL brackets and oversized arches. METHODS: A sample was selected from a pool of 300 consecutive cases treated by a single clinician: 51 patients with SL brackets and oversized wires, and 55 with CL brackets. These two groups were compared with a control group of 20 patients. All plaster models were scanned and dental landmarks were measured to identify changes from commencement (T0) to conclusion (T1) of treatment. Lateral cephalograms were analyzed for changes in the lower incisor (IMPA) and the first lower molar distal angulation (MAng). Intraoperator reliability was tested with linear regression analysis. To assure all groups were comparable at T0, an ANOVA test with a 95%confidence interval (CI) was performed for all values. To assess changes from T0 to T1 in all groups, a Student's t-test with 95% CI was used. Finally, results from the three groups were compared using an ANOVA-test (95% CI) and a post-hoc test. RESULTS: Increases in all the transverse variables were recorded in the two groups treated (SL and CL), except for the lower intercanine distance in the SL group. IMPA difference from T0 to T1 was higher in the CL group, and molar distal angulation (MAng) took place in the SL group. CONCLUSIONS: Self-ligating brackets with oversized arches and conventional ligating brackets showed increases in all variables in the transverse plane, except for the SL group at the mandibular intercanine distance. In comparison with the CL group, fewer different IMPA values were observed in the SL group, in which distal molar angulation occurred.

In Vitro Study of Shear Bond Strength in Direct and Indirect Bonding with Three Types of Adhesive Systems.

This study aimed to compare the shear bond strength (SBS) and adhesive remaining index (ARI) using one conventional and two novel adhesive systems with clinical step reduction and direct and indirect bonding. A sample of 72 human premolars were divided into six groups of 12 samples. The first three groups (G1, G2, G3) were bonded with a direct technique, while the remaining groups (G4, G5, G6) were bonded by the indirect technique. Groups G1 and G4 used conventional acid-etching primer composite (XT); groups G2 and G5 used self-etching bonding (BO), and groups G3 and G6 had an acid-etching treatment followed by a self-adhesive composite (OC). All groups were exposed to thermocycling. Shear bond strength was analyzed with a universal test machine, and the ARI was examined with 4× magnification. The results showed statistically significant differences between the three adhesive systems. The highest strength values were observed in the XT group G1 (13.54 ± 4 MPa), while the lowest were shown in the BO G2 samples (5.05 ± 2 MPa). There was no significant difference between the direct or indirect bonding techniques on the three compared groups. The type of primer and bonding material significantly influenced the SBS. Values with self-etching bonding were below the minimum recommended for clinical use (5.9-7.8 MPa). There was no difference between indirect and direct bonding techniques. The lowest ARI scores (0-1) were observed in both self-etching and BO groups. Further clinical studies are needed to compare in vivo results.

Correction of mandibular deviation and maxillary occlusal canting with mandibular "early" surgery and microscrews: Two case reports.

Facial asymmetry is a common complaint in patients with facial concerns. Some patients have mandibular asymmetries that have light maxillary cant compensation due to a reduced gingival exposure. A common treatment in facial asymmetries is bimaxillary surgery treatment. However, there are no cases of non-severe occlusal plane canting (OPC) with mandibular asymmetry treated with mandibular surgery and miniscrews for the extrusion of the maxillary molars. The aim of this article is to show how to correct mandibular asymmetries combined with OPC by making a single mandibular "early surgery" combined with the extrusion of the maxilla with miniscrews to correct the occlusal plane in order to avoid a Le Fort I surgery. This type of treatment provides lower medical costs, shorter surgeries, and less postoperative discomfort and invasion for patients.

"In Vitro" Study About Variables that Influence in Arch Friction with Conventional and Self-Ligating Brackets.

Many advantages have been described surrounding self-ligating (SL) brackets compared to metallic conventional ligating (CL) brackets, such as: Less total treatment time, alignment efficiency, patient comfort, plaque retention, and low friction. The objective of this in vitro simulation was to know the variables that affect arch displacement in CL and SL brackets-active (ASL) and passive (PSL)-and analyze if static friction values are affected by bracket design, arch wire section, kind of ligature, and use of a friction reducer agent (FRA) in a wet state. Larger values of static friction were found in CL with metallic ligature (ML) (8.01 ± 1.08 N/mm) and elastic ligature (EL) (6.96 ± 0.48 N/mm). Lower values were found in PSL brackets combined with FRA (0.58 ± 0.21 N/mm). The study was carried out using different stereographical models of a maxillary upper right quadrant with canine, first and second premolar, and first molar bonded brackets. A section of 25 mm of 0.019 × 0.025" stainless steel arch with a rectangular section (SS) and hybrid section (HY) was inserted into the different bracket models. Static friction values were collected using a universal test machine in wet conditions and testing the effect of a friction reducer agent (FRA). To assure the reliability of the study, different wire combinations were repeated after two weeks by the same operator and a linear analysis of regression was done. Each bracket model analysis-with the different wires, use of the FRA, and comparison among brackets in similar conditions-was done using an ANOVA test with a confidence interval of 95% and comparative Post-Hoc tests (LSD). In this in vitro simulation we found higher static friction values in CL compared to ASL and PSL. In PSL, lower values were achieved. CL brackets using ML showed the highest static friction values with a great variability. In this setting, the use of HY wires did not reduce static friction values in ASL and PSL, while in CL brackets with EL friction the values were reduced significantly. An FRA combined with ASL reduced significantly static friction values but not with PSL. In the case of CL, the FRA effect was higher with SS and better than with HY wires. ML values were similar to ASL static friction. The direct extrapolation of the results might be inaccurate, since all these findings should be tested clinically to be validated.

Stability of the anterior arm of three different Hyrax hybrid expanders: an in vitro study.

INTRODUCTION: The force applied to the teeth by fixed orthopaedic expanders has previously been studied, but not the force applied to the orthodontic mini-implant (OMI) used to expand the maxilla with Hyrax hybrid expanders (HHE). OBJECTIVE: The aim of this article was to evaluate the clinical safety of the components (OMI, abutment and double wire arms) of three different force-transmitting systems (FTS) for conducting orthopaedic maxillary expansion: Jeil Medical & Tiger Dental™, Microdent™ and Ortholox™. METHODS: For the realization of this in vitro study of the resistance to mechanical load, three different abutment types (bonded, screwed on, and coupling) and three different OMIs' diameters (Jeil™ 2.5 mm, Microdent™ 1.6 mm and Ortholox™ 2.2 mm) were used. Ten tests for each of these three FTS were carried out in a static lateral load in artificial bone blocks (Sawbones™) by a Galdabini universal testing machine, then comparing its performance. Comparisons of loads, deformations and fractures were carried out by means of radiographs of FTS components in each case. RESULTS: At 1- mm load and within the elastic deformation, FTS values ranged from 67 ± 13 N to 183 ± 48 N. Under great deformations, Jeil & Tiger™ was the one who withstood the greatest loads, with an average 378 ± 22 N; followed by Microdent™, with 201 ± 18 N, and Ortholox™, with 103 ± 10 N. At 3 mm load, the OMIs shaft bends and deforms when the diameter is smaller than 2.5 mm. The abutment fixation is crucial to transmit forces and moments. CONCLUSIONS: The present study shows the importance of a rigid design of the different components of HHEs, and also that HHEs would be suitable for maxillary expansion in adolescents and young adults, since its mean expansion forces exceed 120N. Furthermore, early abutment detachment or smaller mini-implants diameter would only be appropriate for children.

A simple method for measuring thickness of gingiva and labial bone of mandibular incisors.

OBJECTIVE: Thin supporting tissues may cause gingival recessions and esthetic problems in the anterior area. The objectives of this study were to present a simple and reliable radiographic technique to measure thickness of alveolar bone labial to mandibular incisors, and to establish a possible correlation of bone thickness with its tissue biotype. METHOD AND MATERIALS: A metal strip was placed over the gingiva of the mandibular incisor axis, and a perpendicular occlusal radiograph was taken of 51 patients. Patients in routine orthodontic practice before any orthodontic treatment was started were distributed into three groups according to their periodontal biotype (A1, thin with < 2 mm keratinized gingiva; A2, thin with > 2 mm; and B, thick with wide zone of keratinized gingiva), as described by Müller and Eger.1 Radiographs were scanned and thickness of gingival tissue and of bone at two levels (at the bone crest and at 3 mm below the bone crest) was measured to the nearest 0.1 mm. Measurements of soft tissue and bone thickness were compared and correlated. RESULTS: Groups A2 and B showed a significant difference in bone thickness at the bone crest. Correlation of bone and gingival thickness was only found in gingival biotype B at 3 mm below the bone crest level only (R = 0.290; P < .001). No other correlation between bone and gingival thickness was observed in any group. CONCLUSIONS: The radiographic technique proposed in this study is a simple and reliable method for calibrating the amount of buccal bone in the mandibular anterior area. It is a cheap and fast diagnostic tool that may help determine the amount of buccal bone and gingival thickness, and therefore avoid excessive radiation to patients. Groups A2 and B showed a significant difference in bone thickness at the bone crest. Although not significant, group A1 showed the lowest values of bone and gingival thickness, whereas group B showed the highest bone and gingival thickness. A clear correlation between thickness of bone and gingiva 3 mm below the cementoenamel junction was found in group B.