Use of ultrasound imaging for assessment of the periodontium: A systematic review.

The objective of this study was to systematically review the literature regarding diagnostic applications of ultrasound imaging for evaluation of the periodontium in humans. The search was conducted on Medline, EMBASE, Web of Science, Scopus, Cochrane, and PubMed up to April 3, 2023. The studies included were exclusively human studies that assessed the periodontium with ultrasound (US) imaging (b-mode). Outcomes measured included alveolar bone level, alveolar bone thickness, gingival thickness, and blood flow quantification. References were imported to Covidence. Two reviewers conducted phases 1 and 2. The JBI risk assessment tool for cross-sectional studies was used. Extracted data included the transducer and measurements used and the study's outcomes. The search yielded 4892 studies after removing duplicates. From these, 25 studies were included and selected for extraction. Included studies retrieved outcomes from US examinations of the periodontal tissues. From the selected studies, 15 used US on natural teeth, 4 used US on implants, 2 used US on edentulous ridges, and 4 used color flow/power in US to evaluate the blood flow. The results of the present systematic review suggest that US might be a feasible and valuable diagnostic tool for the periodontium, with the potential to complement shortfalls of current radiographic technologies.

In vitro biomechanics of divot use, and their placement, in orthodontic aligner therapy.

INTRODUCTION: To evaluate biomechanics of an aligner utilizing divots and the effect of their vertical placement on the right maxillary central incisor. METHODS: An in vitro Orthodontic SIMulator (OSIM) was used to test forces and moments generated by aligners incorporating divots. The OSIM arch was scanned to generate a. STL version that was modified to create four models by placing divots on different positions of the right central maxillary incisor: GI - divots on gingival-third of lingual surface and incisal-third of labial surface; GM - divots on gingival-third of lingual surface and middle-third of labial surface; MI - divots on middle-third of lingual surface and incisal-third of labial surface; MM - divots on middle-third of lingual surface and middle-third of labial surface. Aligners (n = 30/model) were fabricated using a 0.75 mm thick polyethylene terephthalate material and Biostar® machine following the manufacturer's recommendations. A one-way MANOVA followed by one-way ANOVA (α = 0.05) was utilized to test effect of models on buccolingual force (Fy) and mesiodistal moment (Mx) at 0.20 mm of lingual displacement of the right maxillary central incisor. RESULTS: Mean Mx for GI (-5.68 ± 7.38 Nmm), GM (3.75 ± 5.54 Nmm), MI (-4.27 ± 1.48 Nmm) and MM (1.96 ± 0.99 Nmm) models showed statistical differences between GI and GM, GI and MM, GM and MI and MI and MM. GI exerted the largest Fy (1.87 ± 0.75 N) followed by GM (1.10 ± 0.47 N), MI (0.70 ± 0.23 N) and MM (0.28 ± 0.08 N) with significant differences between GI and GM, GI and MI, GI and MM and GM and MM models. CONCLUSIONS: Vertical divot placement on a right central incisor had a significant effect on aligner biomechanics. Buccolingual forces exerted by models GI, GM and MI were within the range suggested by literature for bodily tooth movement without major root tipping for GM and MI models.

The repeatability of periodontal imaging with intraoral ultrasound scanning.

OBJECTIVE: Ultrasound is a non-invasive and low-cost diagnostic tool widely used in medicine. Recent studies have demonstrated that ultrasound imaging might have the potential to be used intraorally to assess the periodontium by comparing it to current imaging methods. This study aims to characterize the repeatability of intraoral periodontal ultrasound imaging. MATERIALS AND METHODS: Two hundred and twenty-three teeth were scanned from fourteen volunteers participating in this study. One operator conducted all the scans in each tooth thrice with a 20 MHz intraoral ultrasound. The repeatability of three measurements, alveolar bone crest to the cementoenamel junction (ABC-CEJ), gingival thickness (GT), and alveolar bone thickness (ABT), was calculated with intercorrelation coefficient (ICC). Measurements were also compared with mean absolute deviation (MAD), repeatability coefficient (RC), and descriptive statistics. RESULTS: ICC scores for intra-rater repeatability were 0.917(0.897,0.933), 0.849(0.816,0.878), and 0.790(0.746,0.898), MAD results were 0.610 mm (± 0.508), 0.224 (± 0.200), and 0.067 (± 0.060), and RC results were 0.648, 0.327, and 0.121 for ABC-CEJ, GT, and ABT measurements, respectively. CONCLUSION: Results of the present study pointed towards good or excellent repeatability of ultrasound as a measurement tool for periodontal structures. CLINICAL RELEVANCE: Clinicians could benefit from the introduction of a novel chairside diagnostic tool. Ultrasound is a non-invasive imaging assessment tool for the periodontium with promising results in the literature. Further validation, establishment of scanning protocols, and commercialization are still needed before ultrasound imaging is available for clinicians.

Idiopathic condylar resorption in adolescents: A scoping review.

OBJECTIVE: Idiopathic condylar resorption (ICR), also known as progressive condylar resorption, is poorly understood, particularly in adolescent patients. Therefore, this scoping review aims to summarize the available literature on the prevalence, aetiology, pathogenesis, diagnostic process, treatment and/or any outcome regarding ICR in adolescent individuals. METHODS: This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and its extension for scoping reviews (PRISMA-ScR), as well as Joanna Briggs Institute studies. The search strategy was defined adopting a core search structure for each source, and the search was performed on MEDLINE, EMBASE, Cochrane Library, Web of Science, Scopus and Google Scholar. After duplicate removal, two independent reviewers screened abstracts, followed by complete articles, to achieve the definition of included studies. Data collection was performed, and the extracted data were organized in tabular form, along with a narrative summary of main findings that aligns with the objective of this review. RESULTS: Six observational studies were included in this review. Three studies focused on signs and symptoms, one on prevalence and signs and symptoms, one on treatment and one on disease pathogenesis. CONCLUSION: This scoping review revealed inadequate published research regarding prevalence, aetiology, early diagnosis, pathogenesis and treatment of ICR in adolescents.

The in vitro biomechanics of anterior arch expansion using fixed lingual appliances with coil springs or archwire stops.

INTRODUCTION: The presented study investigates differences in the biomechanics of straight and mushroom fixed lingual appliances when implementing coil springs and stops for anterior arch expansion. MATERIALS AND METHODS: An in vitro orthodontic simulator was used to measure three-dimensional forces and moments on each tooth of a simulated maxillary arch. Mushroom and straight archwire forms of 0.016″ NiTi round archwire were considered, using 0.010″ × 0.030″ NiTi open coils and 0.016″-0.018″ archwire stops (n = 44 per group). Teeth in the anterior dental arch were moved from a neutral to crowded position to replicate anterior crowding of central and lateral incisors. Forces and moments of interest for lateral incisors and first premolars were compared using repeated measures mixed multivariate analysis of variance (α = 0.05). RESULTS: Three comparisons between straight versus mushroom archwires and two comparisons of coil springs vs. stops were not statistically significant. Overall, it was found that the use of a straight lingual archwire produced larger differences in forces and moments between using stops and coil springs than when using a mushroom archwire. Using stops produced larger forces and moments for both types of archwires as compared to using coil springs. The largest expansion forces were produced using straight archwires with stops, exceeding 3.0 N of force. Straight archwires with coil springs produced the lowest expansion forces on lateral incisors, just exceeding 1.5 N. CONCLUSIONS: The findings of this study have elucidated significant differences in the biomechanics of transverse arch expansion using straight or mushroom fixed lingual appliances with coil springs or stops.

Measuring the alveolar bone level in adolescents: A comparison between ultrasound and cone beam computed tomography.

BACKGROUND: Cone beam computed tomography (CBCT) is an imaging modality, which is used routinely in orthodontic diagnosis and treatment planning but delivers much higher radiation than conventional dental radiographs. Ultrasound is a noninvasive imaging method that creates an image without ionizing radiation. AIM: To investigate the reliability of ultrasound and the agreement between ultrasound and CBCT in measuring the alveolar bone level (ABL) on the buccal/labial side of the incisors in adolescent orthodontic patients. DESIGN: One hundred and eighteen incisors from 30 orthodontic adolescent patients were scanned by CBCT with 0.3-mm voxel size and ultrasound at 20 MHz frequency. The ABL, distance from the cementoenamel junction (CEJ) to the alveolar bone crest (ABC), was measured twice to evaluate the agreement between ultrasound and CBCT. In addition, the intra- and inter-rater reliabilities in measuring the ABL by four raters were compared. RESULTS: The mean difference (MD) in the ABL between ultrasound and CBCT was -0.07 mm with 95% limit of agreement (LoA) from -0.47 to 0.32 mm for all teeth. For each jaw, the MDs between the ultrasound and CBCT were -0.18 mm (for mandible with 95% LoA from -0.53 to 0.18 mm) and 0.03 mm (for maxilla with 95% LoA from -0.28 to 0.35 mm). In comparison, ultrasound had higher intra-rater (ICC = 0.83-0.90) and inter-rater reliabilities (ICC = 0.97) in ABL measurement than CBCT (ICC = 0.56-0.78 for intra-rater and ICC = 0.69 for inter-rater reliabilities). CONCLUSION: CBCT parameters used in orthodontic diagnosis and treatment planning in adolescents may not be a reliable tool to assess the ABL for the mandibular incisors. On the contrary, ultrasound imaging, an ionizing radiation-free, inexpensive, and portable diagnostic tool, has potential to be a reliable diagnostic tool in assessing the ABL in adolescent patients.

3D Analysis of maxillary incisor root inclinations in cases of unilateral maxillary canine impaction.

OBJECTIVES: To evaluate the association between maxillary incisor root inclinations and unilateral canine impaction. METHODS: A retrospective cross-sectional study of 59 pre-treatment CBCT scans (23 palatal impactions, 10 buccal impactions, and 26 comparison patients). Using Dolphin 3-D Imaging software (Chatsworth, CA), relative incisor angulations to a 3D palatal plane and the shortest distance between the canine crown and the root of the closest lateral incisor were calculated. A one-way analysis of variance was used to determine whether there were any differences between the three independent groups of impactions concerning the four continuous dependent variables incisor root inclination for each maxillary incisor. RESULTS: Patients with unilaterally impacted maxillary canines demonstrate significant differences in the root inclination position on the ipsilateral (0.0001 > P = 0.002) but not contralateral side. While palatal impactions (PIC) are associated with buccally positioned roots of the ipsilateral lateral (-9.05 degrees) and central incisors (-7.91 degrees), buccal impactions (BIC) are only associated with palatally positioned roots of the ipsilateral lateral incisors (+10.40 degrees) alone. A more labial position of the lateral incisor root was correlated with a more proximally located, coronally positioned, and medially displaced adjacent PIC (0.013 > P < 0.026). LIMITATIONS: This is a retrospective cross-sectional convenience sample. CONCLUSIONS: Patients with impacted maxillary canines, whether PIC or BIC, do not show generalized retroclination or proclination of all four maxillary incisor roots. Instead, changes in incisor root inclination were only ipsilateral to the impacted canine. BIC is only associated with palatal displacement of the ipsilateral lateral incisor root, whereas PIC is associated with labial root displacement of both ipsilateral incisors.

Prevalence of maxillary sinus hypoplasia and association with variations in the sinonasal complex: a cone beam CT study.

OBJECTIVE: Understanding of maxillary sinus hypoplasia (MSH) and associated sinonasal variants is paramount to the diagnostic and therapeutic success of maxillary sinus and maxillary dental implant surgery. The purpose of this work was to explore the prevalence of MSH, frequency of mucosal thickening, and anatomical variations in the sinonasal complex. METHODS: Retrospective case-control design based on cone beam CT images of dental patients with MSH and matched for age and gender. MSH type and sinonasal variables were recorded. RESULTS: One thousand three hundred seventy cone beam CT scans were analyzed for MSH. MSH prevalence was 6% (n=82), matched with 82 controls= 100 females and 64 males, mean age 37.1±14.1 years. Most MSH were type I, 69.5%, 80.5% unilateral, 65.9% associated with no or mild mucosal thickening. Associated sinonasal anatomical variations were <27% except for deviated/hyperplastic (DH) meatus, 48.8%. Within the MSH group, significant associations were presented between MSH type, mucosal thickening, and DH nasal meatus. MSH group vs controls showed a significant difference in mucosal thickening (OR 5.2, 95% CI 2.0-17.3) and DH meatus (OR 1.6, 95% CI 1.4-2.1). CONCLUSIONS: A hypoplastic maxillary sinus with abnormal or absent uncinate process is associated with advanced mucosal thickening and may present with altered anatomy of the lateral wall of the nasal cavity causing its approximation to the orbital floor. CLINICAL RELEVANCE: Pre-surgical knowledge of altered anatomy in the sinonasal complex is crucial in dental implant or sinus surgery.

An in vitro evaluation of orthodontic aligner biomechanics around the maxillary arch.

INTRODUCTION: The objective of this study was to evaluate the forces and moments exerted by orthodontic aligners on 3 different displaced maxillary teeth and their adjacent supporting teeth. METHODS: An in vitro orthodontic simulator was used to measure the forces and moments of a 0.75-mm thick glycol-modified polyethylene terephthalate material for 3 maxillary teeth: central incisor, canine, and second premolar. Forces and moments were recorded for tested teeth displaced lingually one by one for 0.20 mm. Repeated measures of multivariate analysis of variance was used to assess the outcome. RESULTS: The mean buccolingual force applied on a displaced canine (2.25 ± 0.38 N) was significantly (P <0.001) more than the central incisor (1.49 ± 0.18 N) and second premolar (1.50 ± 0.16 N). The mean moment (that tends to tip the teeth buccally) exerted on a canine (-20.11 ± 5.27 Nmm) was significantly more (P <0.001) than the central incisor (-8.42 ± 1.67 Nmm) and second premolar (-11.45 ± 1.29 Nmm). The forces and moments acting on teeth adjacent to the displaced tooth were clinically significant and acted in opposing directions to those on the displaced tooth. CONCLUSIONS: The results of this study highlighted that for the same amount of displacement on a given tooth, the forces and moments imposed by the orthodontic aligner depend on location around the arch. These findings highlight the need to further study aligner mechanics around the dental arch and optimize aligner design to impose desired mechanical loads to avoid detrimental effects during orthodontic tooth movement.

Influence of Sponsorship Bias on Treatment Effect Size Estimates in Randomized Trials of Oral Health Interventions: A Meta-epidemiological Study.

BACKGROUND: In this meta-epidemiological study, we aimed to examine associations between treatment effect size estimates and sponsorship bias in oral health randomized clinical trials. METHODS: We selected oral health related meta-analyses that included a minimum of five randomized controlled trials. We extracted data, in duplicate, related to influence of sponsorship bias. We quantified the extent of bias associated with influence of sponsorship on the magnitude of effect size estimates of continuous variables using a two-level meta-meta-analytic approach with random-effects models to allow for intra- and inter-meta-analysis heterogeneity. RESULTS: We initially identified 540 randomized trials included in 64 meta-analyses. Risk of sponsorship bias was judged as being "unclear" in 72.8% (n = 393) of the trials, while it was assessed as "low" in 16.7% (n = 90) and as "high" in 10.6% (n = 57) of the trials. Using a meta-epidemiological analysis (37 meta-analyses, including 328 trials that analyzed 85,934 patients), we identified statistically significant larger treatment effect size estimates in trials that had "high or unclear" risk of sponsorship bias (difference in treatment effect size estimates=0.10; 95% confidence intervals: 0.02 to 0.19) than in trials that had "low" risk of sponsorship bias. CONCLUSIONS: We identified significant differences in treatment effect size estimates between dental trials based on sponsorship bias. Treatment effect size estimates were 0.10 larger in trials with "high or unclear" risk of sponsorship bias. PRACTICAL IMPLICATIONS: Clinicians should have an adequate knowledge of sponsorship bias in a clinical trial and be able to estimate the degree to which the conclusions of a systematic review are synthesized and interpreted, based on trials with low risk of sponsorship bias.

Effectiveness of clear aligner therapy for orthodontic treatment: A systematic review.

OBJECTIVE: To analyse through a systematic review the effectiveness of clear aligners by assessing: (a) predictability of clear aligners and (b) treatment outcome comparison of clear aligner therapy with fixed appliance therapy. METHODS: An electronic search was made from January 2014 to April 2019 using MEDLINE, Embase, Web of Science and LILACS databases without any limitations on language. Three reviewers independently assessed the articles. Quality assessment of observational studies and randomized control trial was done by using the ROBINS tool and Cochrane risk of bias tool, respectively. GRADE instrument was used to assess certainty level for each identified outcome. RESULTS: Seven eligible articles (one randomized controlled trial and six retrospective cohort) were included in our systematic review. Most of the studies (six out of seven) had a moderate risk of bias and one had a high risk of bias. CONCLUSIONS: 'Low to moderate level' of certainty in regard to specific clear aligner therapy tooth movements' efficiency was identified. Clear aligners may produce clinically acceptable outcomes that could be comparable to fixed appliance therapy for buccolingual inclination of upper and lower incisors in mild to moderate malocclusions. However, not all potential clinical scenarios have been assessed in the included studies. Most of the tooth movements may not be predictable enough to be accomplished with only one set of trays with clear aligners despite the recent advances in technology.

Pediatric sleep-disordered breathing in the orthodontic population: Prevalence of positive risk and associations.

INTRODUCTION: Pediatric sleep-disordered breathing (SDB) describes a spectrum of disease ranging from snoring to upper airway resistance syndrome and obstructive sleep apnea (OSA). Anatomical features assessed during orthodontic exams are often associated with symptoms of SDB in children. Hence, we need to determine the prevalence of positive risk for SDB in the pediatric orthodontic population compared with a general pediatric population and understand comorbidities associated with SDB risk among orthodontic patients. METHODS: Responses from Pediatric Sleep Questionnaires were collected from 390 patients between the ages of 5 and 16 years, seeking orthodontic treatment. Prevalence of overall SDB risk, habitual snoring, and sleepiness were determined in the orthodontic population and compared with those previously reported by identical methods in the general pediatric population. Additional health history information was used to assess comorbidities associated with SDB risk in 130 of the patients. RESULTS: At 10.8%, the prevalence of positive SDB risk was found to be significantly higher in the general pediatric orthodontic population than in a healthy pediatric population (5%). The prevalence of snoring and sleepiness in the orthodontic population was 13.3% and 17.9%, respectively. Among the comorbidities, nocturnal enuresis (13.6%), overweight (18.2%), and attention deficit hyperactivity disorder (31.8%) had a higher prevalence in orthodontic patients with higher SDB risk (P < 0.05). CONCLUSIONS: There is a higher pediatric SDB risk prevalence in the orthodontic population compared with a healthy pediatric population. Orthodontic practitioners should make SDB screening a routine part of their clinical practice.

Dental imaging of trabecular bone structure for systemic disorder screening: A systematic review.

The purpose of this systematic review was to evaluate the potential use of dental imaging assessment of trabecular bone structure in the maxillomandibular complex as an adjuvant screening tool to identify systemic disorders. Five electronic databases and grey literature were searched. Studies were included if they investigated subjects with altered trabecular bone determined by dental radiographs. The QUADAS-2 assessed the risk of bias (RoB) among the studies, while the GRADE determined the strength of evidence. A total of 14 studies that included 1,466 individuals were considered eligible for the qualitative analysis. All studies presented an overall low RoB and low concern regarding applicability. Systemic disorders such as osteoporosis, osteogenesis imperfecta, diabetes, and primary hyperparathyroidism, with their respective control groups, were analyzed among the included studies. Osteoporosis was the condition presenting the most significant results, and 72% of the studies detected changes in the maxillomandibular trabecular bone structure. Studies exploring diabetic edentulous patients found less dense trabecular bone pattern (p < 0.05). In summary, periapical and panoramic radiographs, computed tomography, and cone beam computed tomography imaging could be considered useful for the assessment of the mandibular trabecular bone structure of patients affected by osteoporosis and patients with diabetes.

Additional appointments and discomfort associated with compliance-free fixed Class II corrector treatment: a systematic review.

OBJECTIVE: A critical analysis of the literature to determine the prevalence and type of emergency/additional appointments, and discomfort levels associated with fixed Class II correctors. METHODS: Studies examining patient's sources of discomfort or emergency appointments associated with compliance-free Class II correctors were included. Comprehensive searches up to July 2018 were conducted using the following databases: MEDLINE (OvidSP), PubMed, Web of Science, and Embase. A partial grey literature search was taken using Google Scholar and OpenGrey. Two reviewers independently performed the selection process and risk of bias assessment. The Newcastle-Ottawa Scale for cross-sectional studies were used. A summary of the overall strength of evidence was presented using 'Grading of Recommendations, Assessment, Development and Evaluation' (GRADE) tool. Included studies were evaluated according to their design, study quality, consistency, and directness. RESULTS: The selected studies were published between 2001 and 2018, and the number of patients per studied group ranged from 8 to 182. One thousand five hundred forty-two patients were evaluated in total. The patients' mean age at start of treatment ranged from 10 to 16.9 years and the fixed Class II corrector treatment duration ranged from 4 to 12 months. The included studies in this systematic review were too clinically heterogeneous (different appliances, different data recollection processes) to justify a meta-analysis. LIMITATIONS: This review was not previously registered. A low level of evidence was observed among the two randomized trials, the 10 cohorts and three cross-sectional studies identified. CONCLUSIONS: The main source of discomfort from Forsus-type appliances appears to be soreness in the cheeks (low level of evidence with a weak recommendation strength). Most evaluated patients treated with a Herbst appliance, regardless of design, will experience complications (fractures and/or dislodging) requiring emergency appointments (low level of evidence with a weak recommendation strength). REGISTRATION: The review protocol was not registered.

Measurement of forces and moments around the maxillary arch for treatment of a simulated lingual incisor and high canine malocclusion using straight and mushroom archwires in fixed lingual appliances.

INTRODUCTION: An Orthodontic SIMulator (OSIM) was used to investigate the propagation of forces and moments around a simulated archform for a gingival displaced canine and lingual displaced lateral incisor using fixed lingual orthodontic appliances. METHODS: In-Ovation L self-ligating lingual brackets were bonded to anatomically shaped teeth on the OSIM, and the teeth were positioned such that a G4 NiTi 0.016" large maxillary mushroom archwire could be ligated in passive position. Each trial consisted of two movements: a 3mm lingual displacement of the 1-2 lateral incisor at 0.2 mm increments, and a 1.5 mm gingival displacement of the 2-3 canine at 0.15 mm increments (n = 50). Anterior brackets were repositioned to accommodate G4 NiTi 0.016" universal straight archwires (n = 50). Tests were completed at 37°C, and force and moment data in all directions was collected for each tooth around the arch at all increments. RESULTS: In general, the straight archwire produced significantly larger forces and moments at the centre of resistance for teeth of interest than did mushroom archwires. Specifically, the straight archwire produced 2.62 N and 3.81 N more force in the direction of tooth movement on the tooth being moved for a gingival displaced canine and lingual displaced lateral incisor, respectively, as compared to mushroom archwires. CONCLUSIONS: Results from this study suggest that mushroom archwires may provide better mechanics for movement of teeth in the anterior segment when using a round archwire; however, only biomechanical data was considered in this study and there are many factors that need to be considered in treatment planning.

The effect of buccal-lingual slot dimension size on third-order torque response.

Introduction: The focus of the presented study was to investigate the effect of buccal-lingual (B-L) orthodontic bracket slot dimension on third-order torque mechanics. Materials and methods: Three types of orthodontic brackets and two archwire sizes were considered. Ortho Classic H4 (0.026″ B-L slot, passive), Ormco Damon Q (0.028″ B-L slot, passive), and In-Ovation R (0.028″ slot, active) brackets were tested using 0.017″ × 0.025″ and 0.019″ × 0.025″ beta-titanium archwires. An in vitro orthodontic torque simulator (OTS) was used to rotate archwires relative to a single bracket while recording forces and moments in three directions. For each bracket-archwire combination, a total of n = 47 samples were tested. Repeated measures analysis of variance between brackets was conducted for third-order torque values at 3° increments between 9° and 30° during loading and unloading for each archwire size. Results: Statistically significant differences between H4 and Q brackets were only found for 0.017″ × 0.025″ archwires during loading, and 0.019″ × 0.025″ archwires during unloading. Conversely, differences between H4 and R brackets were found for both archwires during loading and unloading phases. Finally, when using a 0.017″ × 0.025″ archwire the H4 brackets reached the 5 Nmm threshold before R and Q brackets; however, there was little difference found when using a 0.019″ × 0.025″ archwire. Conclusions: The concept of using a smaller B-L bracket slot dimension in orthodontic treatment showed it may theoretically allow for more options, primarily using smaller archwires to correct third-order rotational misalignments. However, it is suspected that bracket material limitations and added loading on the door currently prevent this from being clinically applicable.

Comparison of third-order torque simulation with and without a periodontal ligament simulant.

INTRODUCTION: This in-vitro study presents the development and validation of an artificial tooth-periodontal ligament-bone complex (ATPBC) and comparison of its behavior with that of rigid dowels during third-order torque simulation. METHODS: ATPBCs were coupled using a 1:1 mixture of room-temperature vulcanization silicone and gasket sealant to act as a periodontal ligament simulant (PDLS). PDLS thicknesses ranging from 0.2 to 0.7 mm, in increments of 0.1 mm (n = 5 for each thickness), were tested using a linear crown displacement procedure. A suitable PDLS thickness was selected for use in third-order torque simulations to compare ATPBC (n = 29) and rigid (n = 24) dowel behavior. Their results were compared for archwire rotations up to 20° for both loading and unloading curves with repeated-measures analysis of variance. RESULTS: When used in third-order torque simulations, the ATPBC dowels with a 0.5-mm PDLS thickness showed a statistically significant difference from rigid dowels (P = 0.020), with a 95% confidence interval (0.254, 2.897 N·mm) and a mean difference of 1.575 N·mm. CONCLUSIONS: Inclusion of a PDLS in an ATPBC resulted in a statistical difference when compared with rigid dowels; however, the region where behavior differed was at low angles of archwire rotation, and the resultant torque was arguably outside a clinically relevant range.

Mandibular advancement appliances for the treatment of paediatric obstructive sleep apnea: a systematic review.

OBJECTIVE: To evaluate the effectiveness of mandibular advancement appliances (MAAs) for treatment of pediatric obstructive sleep apnea (OSA). METHODS: Several electronic databases (The Cochrane Database, EMBASE, Healthstar, MEDLINE, PubMed) were systematically searched, as well as a limited grey literature (Google Scholar) and manual searches. A health sciences librarian helped with the selection of Medical Subject Headings (MeSH), key words, and combinations of key words with truncations to account for any differences in controlled terminology in the different databases. Only studies that evaluated the effects of MAAs in children with OSA were pursued. RESULTS: Only 4 articles satisfied all inclusion criteria. Selected studies were retrospective except one study that was a quasi-randomized clinical trial. High risk of bias (Cochrane Risk of Bias assessment) was judged in all included studies. Based on the limited available evidence use of MAAs in a POSA population may result in improvements in Apnea Hypopnea Index (AHI) scores. However complete normalization of AHI scores was not demonstrated. Heterogeneity in study designs and collected information precluded meta-analysis. LIMITATIONS: There are significant weaknesses in the existing evidence due primarily to absence of control groups, small sample sizes, lack of randomization and short-term results. Determination of AHI scores with MAAs still in the mouth should be avoided. CONCLUSIONS: The current limited evidence may be suggestive that MAAs result in short-term improvements in AHI scores, but it is not possible to conclude that MMAs are effective to treat pediatric OSA. Medium- and long-term assessments are still required.

In vitro fracture toughness of commercial Y-TZP ceramics: a systematic review.

PURPOSE: The aim of this review was to assess research methods used to determine the fracture toughness of Y-TZP ceramics in order to systematically evaluate the accuracy of each method with regard to potential influencing factors. MATERIALS AND METHODS: Six databases were searched for studies up to April 2013. The terms "tough*," "critical stress intensity factor," "zirconi*," "yttri*," "dent*," "zirconia," "zirconium," and "stress" were searched. Titles and abstracts were screened, and literature that fulfilled the inclusion criteria was selected for a full-text reading. Test conditions with potential influence on fracture toughness were extracted from each study. RESULTS: Ten laboratory studies met the inclusion criteria. There was a significant variation in relation to test method, ambient conditions, applied/indentation load, number of specimens, and geometry and dimension of the specimen. The results were incomparable due to high variability and missing information. Therefore, 10 parameters were listed to be followed to standardize future studies. CONCLUSIONS: A wide variation in research methods affected the fracture toughness reported for Y-TZP ceramics among the selected studies; single-edge-precracked beam and chevron-notched-beam seem to be the most recommended methods to determine Y-TZP fracture toughness; the indentation methods have several limitations. CLINICAL SIGNIFICANCE: The accurate calculation of toughness values is fundamental because overestimating toughness data in a clinical situation can negatively affect the lifetime of the restoration.

Association between tension-type headache and migraine with sleep bruxism: a systematic review.

AIM: To evaluate the association between tension-type headache and migraine with sleep bruxism (SB). BACKGROUND: The association between SB and headaches has been discussed in both children and adults. Although several studies suggested a possible association, no systematic analysis of the available published studies exists to evaluate the quantity, quality, and risk of bias among those studies. METHODS: A systematic review was undertaken, including articles that classified the headaches according to the International Classification of Headache Disorders and SB according to the criteria of the American Association of Sleep Medicine. Only articles in which the objective was to investigate the association between primary headaches (tension-type and migraine) and SB were selected. Detailed individual search strategies for The Cochrane Library, MEDLINE, EMBASE, PubMed, and LILACS were developed. The reference lists from selected articles were also checked. A partial grey literature search was taken by using Google Scholar. The methodology of selected studies was evaluated using the quality in prognosis studies tool. RESULTS: Of 449 identified citations, only 2 studies, both studying adults, fulfilled the inclusion criteria. The presence of SB significantly increased the odds (study 1: odds ratio [OR] 3.12 [1.25-7.7] and study 2: OR 3.8; 1.83-7.84) for headaches, although studies reported different headache type. CONCLUSION: There is not enough scientific evidence to either support or refute the association between tension-type headache and migraine with SB in children. Adults with SB appear to be more likely to have headache.