Effect of post-printing curing time on cytotoxicity of direct printed aligners: A pilot study.

INTRODUCTION: The aim of this in vitro study was to examine the potential impact of different curing times of 3D-printed orthodontic aligners on their cytotoxicity. METHOD: Some 60 samples of aligner material were directly 3D printed using Tera Harz TC-85 DAC resin and randomly allocated to three different curing time groups (14, 24 and 50 min). Zendura FLX samples were used as control. The samples were incubated in saliva for 14 days, and then the supernatant was collected. Human gingival fibroblasts (HGF-1)-CRL2014 were used to evaluate potential cytotoxicity. Furthermore, HGF-1 cells were plated on the samples as well as on a glass control sample. After 72 h of growth, their viability was tested. RESULTS: Compared with the glass, only the 50-min curing time markedly reduced fibroblast cell growth. Additionally, a negative linear trend was observed between curing time and fibroblast growth. In comparison with the aligner control group, all samples, including the aligner control samples, exhibited a significant reduction in the viability of human fibroblasts when exposed to saliva. CONCLUSIONS: 3D directly printed aligners showed a cytotoxic effect similar to that of thermoformed conventional aligners in terms of fibroblasts growth. A linear trend was found between curing time and cells growth, indicating that directly printed aligners could exhibit higher cytotoxicity if exposed to a longer curing time. This dependence on curing time underscores the importance of following a strict manufacturing process.

Accuracy of direct insertion of TADs in the anterior palate with respect to a 3D-assisted digital insertion virtual planning.

BACKGROUND: Direct and 3D-assisted methods are an available alternative when inserting temporary anchorage devices (TADs) in the anterior palate for orthodontic anchorage. This study aimed to evaluate the differences between a planned insertion versus a direct method on digital models. SETTINGS AND SAMPLE POPULATION: Seventy TADs were inserted by the direct insertion method in 35 patients who needed palatal TADs for orthodontic anchorage. For each patient, placement was independently planned by the superimposition of lateral cephalograms and corresponding plaster models. After mini-implant placement, impressions were taken with scanbodies. For the measurement of both linear and angle deviations, virtual planning models and postoperative oral scans were compared using 3D software for automatic surface registration and calculations. RESULTS: Comparing TADs positioned by the direct method and the digitally planned method, a mean linear distance was found of 2.54 ± 1.51 mm in the occlusal view and 2.41 ± 1.33 mm in the sagittal view. No significant difference has been found between TADs positioned in the right and left palatal sides. A mean distance of 7.65 ± 2.16 mm was found between the tip of the digitally planned TAD and the central incisors root apex. CONCLUSIONS: Both direct and 3D-assisted TAD insertion methods are safe and accurate in the anterior palate. However, the use of insertion guides facilitates TAD insertion, allowing less-experienced clinicians to use palatal implants.

Prevalence of temporomandibular disorder pain, jaw noises and oral behaviours in an adult Italian population sample.

To evaluate the prevalence of temporomandibular disorder pain (TMD-pain), temporomandibular joint (TMJ) noises, oral behaviours in an Italian adult population sample, their possible association with gender, oral behaviours, self-reported facial trauma and orthodontic treatment. Subjects older than 18 years were recruited from general population in public spaces during their daily life. A specific questionnaire was developed to collect data on TMD-pain, TMJ noises, oral behaviours, orthodontic treatment and facial trauma. A total of 4299 subjects were included in the study. The most common symptom in the sample was TMJ clicking (30.7%), followed by TMD-pain (16.3%) and TMJ crepitus (10.3%). Oral behaviours were reported in 29% of the sample; 43.6% of the sample reported a previous or ongoing orthodontic treatment. TMD-pain and TMJ clicking were significantly associated to gender, oral behaviours and a positive history of previous facial trauma. Crepitus was significantly associated to oral behaviours, facial trauma and higher age. Ongoing orthodontic treatment was significantly associated to TMD-pain and TMJ sounds. In a general Italian adult population sample, TMD-pain is associated to female gender and is less prevalent than TMJ clicking. TMDs are associated to trauma and oral behaviours.

Association between posterior crossbite, skeletal, and muscle asymmetry: a systematic review.

BACKGROUND: Of the various malocclusions, unilateral posterior crossbite has often been associated to skeletal and muscular asymmetrical growth and function. OBJECTIVE: To assess, by systematically reviewing the literature, the association between unilateral posterior crossbite (UPCB) and morphological and/or functional asymmetries (i.e. skeletal, masticatory muscle electromyographic (EMG) performance, bite force, muscle thickness, and chewing cycle asymmetries). MATERIALS AND METHODS: A literature survey covering the period from January 1965 to June 2015 was performed. Two reviewers extracted the data independently and assessed the quality of the studies. RESULTS: The search strategy resulted in 2184 citations, of which 45 met the inclusion criteria. The scientific and methodological quality of these studies was medium-low, irrespective of the association reported. In several studies, posterior crossbite is reported to be associated to asymmetries in mandibular skeletal growth, EMG activity, and the chewing cycle. Fewer data are available on bite force and masticatory muscle thickness. CONCLUSIONS: The relationship between unilateral posterior crossbite and skeletal asymmetry is still unresolved. To date, most of the studies available report a skeletal asymmetric growth. EMG activity of masticatory muscles is different between crossbite and non-crossbite sides. Subjects with UPCB show smaller bite force than non-crossbite subjects. There is no consistency of studies reporting masticatory muscle thickness asymmetry in UPCB subjects. UPCB is associated to an increase in the reverse chewing cycle. The literature available on the subject is of medium-low scientific and methodological quality, irrespective of the association reported. Further investigations with higher sample size, well-defined diagnostic criteria, rigorous scientific methodologies, and long-term control are needed.

Evaluations of sagittal and vertical changes induced by surgically assisted rapid palatal expansion.

INTRODUCTION: Class II, anterior open bite and/or a steep mandibular plane angle are frequently considered a contraindication to the use of surgically assisted rapid palatal expansion (SARPE). Nevertheless, few studies have investigated the maxillary and mandibular effects after SARPE on the sagittal and vertical planes, with dissimilar results and small samples of patients.The aim of the current study was to evaluate the sagittal and vertical effects after SARPE. METHODS: Twenty-one consecutive adult patients (7 males, 14 females; mean age, 25.6 ± 6.3 years) who required SARPE were included in this study. All patients were subjected to subtotal LeFort I osteotomy with pterygomaxillary disjunction. Lateral cephalometric radiographs were taken during the preoperative assessment (T0) and 6 months after the end of the expansion (T1). Cephalometric measurements were realized at T0 and T1 for all the patients. Independent-sample t test and analysis of variance were used. RESULTS: Statistically significant changes were observed only in upper incisor^NA (P = 0.04). No skeletal sagittal or vertical variation was found after SARPE. CONCLUSIONS: Class II, anterior open bite and/or a steep mandibular plane angle cannot be considered an outright contraindication to its use. Upper incisor palatal inclination could result after SARPE.

Association between posterior crossbite, masticatory muscle pain, and disc displacement: a systematic review.

BACKGROUND: Among different malocclusions, posterior crossbite is thought to have a strong impact on the correct functioning of the masticatory system. OBJECTIVE: To assess, by systematically reviewing the literature, the association between posterior crossbite and different temporomandibular disorder (TMD) diagnosis: disc displacement and masticatory muscle pain. MATERIALS AND METHODS: A literature survey covering the period from January 1965 to April 2012 was performed. Two reviewers extracted the data independently and assessed the quality of the studies. RESULTS: The search strategy resulted in 2919 citations, of which 43 met the inclusion criteria. The scientific and methodological quality of these studies was found to be medium-low, independently by association reported. In several studies, posterior crossbite is reported to be associated to the development of disc displacement, muscular pain, and tenderness, possibly linked to a skeletal and muscular adaptation of the stomatognathic system. However, the lack of consistency of the results reported deeply reduces the external validity of the studies, with a consequent impossibility to draw definite conclusions. CONCLUSIONS: It is not possible to establish an association between posterior crossbite, muscle pain, and disc displacement because the distribution of the studies supporting or not supporting the association is similar. The consequences of posterior crossbite on the development of TMDs deserve further investigations, with high sample size, well-defined diagnostic criteria, and rigorous scientific methodologies. Finally, long-term controlled studies are needed to identify posterior crossbite as a possible risk factor for TMDs.

Time efficiency of self-ligating vs conventional brackets in orthodontics: effect of appliances and ligating systems.

OBJECTIVES: The aim of the present study was to compare the speed of archwire change between self-ligating (SL) brackets and conventional brackets with elastic and stainless steel (SS) ligatures. MATERIAL AND METHODS: Fifty orthodontic patients, divided into five groups according to the type of fixed appliance and ligating system used (10 subjects=Time 2 SL brackets; 10 subjects = SmartClip SL brackets; 10 subjects = In-Ovation SL brackets; 10 subjects = conventional brackets with SS ligatures, 10 subjects = conventional brackets with elastic ligatures) were included in the study. The clinical phases were carried out by a unique operator experienced in both conventional and SL brackets techniques. Aligning and levelling were completed for each subject. The time needed to remove and ligate .019 x .025 SS archwires in both dental arches was measured for the 5 groups of patients. Independent sample t-test and ANOVA analyses were used. RESULTS: SL brackets had a significantly shorter mean archwire ligation and removal times when compared with conventional brackets with elastic and SS ligatures. The ligation time in the lower arch was affected by the type of SL appliance used. Systems with elastic ligatures had a shorter mean archwire ligation time than systems with SS ligatures. No differences were found between maxillary and mandibular arches in wire ligation and removal times. CONCLUSIONS: The type of bracket has influence on chairside time. SL systems showed a quicker and more efficient wire removal and placement for late orthodontic treatment phases.

Correction of multiple canine impactions by mixed straightwire and cantilever mechanics: a case report.

Background. This case report describes the orthodontic treatment of a woman, aged 17 years, with a permanent dentition, brachyfacial typology, Angle Class I, with full impaction of two canines (13,33), and a severe ectopy of the maxillary left canine. Her main compliant was the position of the ectopic teeth. Methods. Straightwire fixed appliances, together with cantilever mechanics, were used to correct the impaired occlusion and to obtain an ideal torque control. Results and Conclusion. The treatment objectives were achieved in 26 months of treatment. The impactions were fully corrected with an optimal torque. The cantilever mechanics succeeded in obtaining tooth repositioning in a short lapse of time. After treatment, the dental alignment was stable.

Evaluation of the short-term effectiveness of education versus an occlusal splint for the treatment of myofascial pain of the jaw muscles.

BACKGROUND: The authors conducted a clinical trial to compare the effectiveness of an education program with that of an occlusal splint in treating myofascial pain of the jaw muscles across a short period. METHOD: The authors assigned 44 patients randomly to two treatment groups; 41 patients completed the study. The first group (four male, 19 female; mean [standard deviation {SD}] age, 31.4 [14.0] years) received information regarding the nature of temporomandibular disorder (TMD) and self-care measures, whereas the second group (five male, 13 female; mean [SD] age, 31.1 [8.8] years) received an occlusal splint. One of the authors evaluated each patient every three weeks during a three-month treatment period. Treatment outcomes included pain-free maximal mouth opening, spontaneous muscle pain, pain during chewing and headache. RESULTS: After three months, changes in spontaneous muscle pain differed significantly between the education and occlusal splint groups (P = .034; effect size = 0.33). Changes in pain-free maximal mouth opening did not differ significantly between groups (P = .528; effect size = 0.20). Changes of headache and pain on chewing did not differ significantly between groups (P ≥ .550, effect size ≤ 0.10). CONCLUSIONS: During a short period, education was slightly more effective than an occlusal splint delivered without education in reducing spontaneous muscle pain in patients with TMD. Pain-free mouth opening, headache and pain during chewing were not significantly different between the two treatments.