Influence of loading and use of occlusal splint in implant-supported fixed prostheses.

The aim of the study was to assess the tensions generated in the long axis of the implants and the interimplants in the cervical, middle, and apical regions when subjected to different loads with or without interposition of the flat occlusal plane splint. A photoelastic model was made with 2 external hexagon implants located in the space corresponding to the second premolar and molar inferiors. A screw-retained metal superstructure was installed on the implants with a torque of 20 N·cm, and the set (photoelastic model with superstructure) were positioned in the circular polariscope in the dark-field configuration to observe the distribution of isochromatic fringes around the implants and interimplant areas. Photographic records were obtained before the application of the occlusal load with the following loading conditions: 300, 600, and 900 N, with and without interposition of the occlusal plane splint. The decrease in stress with the application of the flat occlusal plane splint became more evident after the application of the 600-N load. Generally, the major stress magnitude occurred in the cervical region for interimplant areas and in the apical region around implants. Use of occlusal splint in the loading of 300, 600, and 900 N reduced tension 33.22%, 66.66%, and 73.33%, respectively, in the samples. It can be concluded that the interposition of the occlusal plane splint caused a reduction in tension resulting from the simulation of occlusal overload.

Tooth embedded in lower lip following dentoalveolar trauma: case report and literature review.

One of the most frequent consequences of trauma to the maxillofacial region is damage to teeth and supporting structures. Such damage can occur either in isolation or in conjunction with other fractures and soft tissue lacerations. In emergency situations, the harm caused to teeth could go unnoticed during the clinical examination, depending on the nature and complexity of the trauma and the primary care team's awareness of orofacial injuries. Fractured incisors often cause lacerations to the soft tissues at the time of trauma. During the diagnosis, particular care must be taken when such a fracture is associated with a soft tissue injury.

Down syndrome: orofacial pain, masticatory muscle hypotonia, and sleep disorders.

The aim of the present study was to investigate orofacial pain in individuals with Down syndrome (DS) and determine possible associations with masticatory muscle hypotonia (MMH), maximum mouth opening (MMO), and sleep disorders. Twenty-three individuals with DS underwent a standardized clinical examination using Axis I of the Diagnostic Criteria for Temporomandibular Disorders, for the diagnosis of pain in the masseter and temporal muscles and temporomandibular joint (TMJ). MMH was investigated using electromyography of the temporal and masseter muscles and the measurement of maximum bite force (MBF). MMO was measured using an analog caliper. Sleep disorders (obstructive sleep apnea [OSA], snoring index [SI], and sleep bruxism index [SBI]) were investigated using type II polysomnography. Statistical analysis was performed. Nonsignificant differences were found in muscle and TMJ pain between the sexes. However, myalgia and referred myofascial pain in the left masseter muscle were more frequent in males (69%) than females (40%). Electrical activity of the temporal (left: p = .002; right: p = .004) and masseter (left: p = .008) muscles was significantly lower in males than in females. MBF range was lower in males than females, indicating the highest MMH among males. OSA, SI, and SBI were identified in both sexes, but with no statistically significant differences. We concluded that myalgia and referred myofascial pain were found in some individuals with DS, especially in males. Arthralgia was found mainly in females. Temporal and masseter myalgia may have exerted an influence on the severity of MMH in males, particularly on the left side.

Evaluation of the masticatory muscle function, physiological sleep variables, and salivary parameters after electromechanical therapeutic approaches in adult patients with Down syndrome: a randomized controlled clinical trial.

BACKGROUND: There are many comorbidities associated with Down syndrome (DS), including obstructive sleep apnea (OSA) and masticatory muscle alteration. Muscular hypotonia, in particular, of the masticatory and oropharyngeal muscles is one of the main characteristics of individuals with DS, resulting in impairments of speech, swallowing, and mastication in these individuals. In addition, total or partial obstruction of the airways during sleep can occur due to pharyngeal hypotonia, leading to snoring and to OSA. This progressive respiratory disorder is associated with a high risk of morbidity and mortality in individuals with DS. The aim of this research is to assess the therapeutic effects of surface neuromuscular electrical stimulation (NMES), the mastication apparatus (MA), and a mandibular advancement oral appliance (OAm) with an embedded thermosensitive microchip on the functions of masticatory muscles (bilateral masseter and temporal muscles), physiological sleep variables, and salivary parameters in adult patients with DS. METHODS: The patients with DS will be randomly selected and divided into three groups (DS-NMES, DS-MA, and DS-OAm) with a minimum of 10 patients in each group. A thermosensitive microchip will be embedded in the OAm to record its compliance. The therapeutic effects on masticatory muscle function will be investigated through electromyography, a caliper, and a force-transducer device; the sleep variables, in turn, will be evaluated by means of polysomnography. The physicochemical and microbiological properties of the saliva will also be analyzed, including the salivary flow, viscosity, buffer capacity, cortisol levels (susceptibility to psychological and/or physical stress), and Pseudomonas aeruginosa levels (risk of aspiration pneumonia) in these patients. The methods determined for this study will be carried out prior to and after 2 months of the recommended therapies. DISCUSSION: The primary outcomes would be the improvement and/or reestablishment of the function of masticatory muscles and the physiological sleep variables in this target public since individuals with DS commonly present generalized muscular hypotonia and dysfunction of the oropharyngeal musculature. As a secondary outcome indicator, the impact of the applied therapies (NMES, MA, and OAm) on the salivary microbiological and physicochemical properties in DS individuals will also be assessed. Furthermore, the compliance of OAm usage will be measured through a thermosensitive microchip. TRIAL REGISTRATION: Registro Brasileiro de Ensaios Clínicos, RBR-3qp5np . Registered on 20 February 2018.

Comparative assessment of different recycling methods of orthodontic brackets for clinical use.

BACKGROUND: This study aimed to assess bond strength of the resin/bracket interface, under in-vitro shear stress, of metal brackets recycled by different clinical protocols. METHODS: Sixty stainless steel orthodontic brackets were bonded on acrylic resin. The Transbond XT™ resin was applied at the base of the bracket aided by a matrix, obtaining 1 mm of thickness, and photoactivated with a LED device (40 s; 500 mW/cm2). Samples were randomly divided into four groups (N.=15) according to the reconditioning/recycling protocol: aluminum oxide (AO) 90 µm; hydrofluoric acid 60 s (HA60); hydrofluoric acid 120 s (HA120); hydrofluoric acid 60 s + silane (HA60S). After recycling, the resin was applied at the base of the bracket for shear testing in a universal testing machine (0.5 mm/min). After reconditioning/recycling, the surfaces were analyzed by Scanning Electron Microscopy. Data obtained after the shear test were subjected to ANOVA and Tukey's test (P<0.05). RESULTS: The AO group presented higher values of shear bond strength compared to the other reconditioning/recycling protocols (P<0.05). The HA120 and HA60S groups presented statistically similar results, but HA120 presented strength below the recommended limit. CONCLUSIONS: The recycling technique by aluminum oxide sandblasting was more effective for reconditioning orthodontic brackets when compared to the other protocols. The reconditioning technique with 10% hydrofluoric acid followed by the application of silane bonding agent may be used as an alternative protocol.

Initial oral biofilm formation on titanium implants with different surface treatments: An in vivo study.

OBJECTIVE: The aim of this study was to examine in vivo the initial bacterial adhesion on titanium implants with different surface treatments. DESIGN: Ten subjects wore oral splints containing machined pure titanium disks (Ti-M), acid-etched titanium (Ti-AE) and anodized and laser irradiated disks (Ti-AL) for 24h. After this period, disks were removed from the splints and adherent bacteria were quantified by an enzymatic assay to assess total viable bacteria and by Real Time PCR to evaluate total bacteria and Streptococcus oralis levels. Additionally, the initial adherent microorganisms were visualized by scanning electron microscopy (SEM). Titanium surface morphology was verified using SEM, and roughness was evaluated by profilometer analysis. RESULTS: Regarding titanium surface roughness, Ti-AL (1.423±0.397) showed significantly higher Ra values than did Ti-M (0.771±0.182) and Ti-AE (0.735±0.196) (p<0.05, ANOVA - Tahame). Ti-AE and Ti-AL presented roughened micro-structure surfaces characterized by open pores, whereas Ti-M showed long grooves alternating with planed areas. Comparing the Ti-M, Ti-AE and Ti-AL groups for viable bacteria (MTT assay), total bacteria and S. oralis quantification (qPCR), no significant differences were observed among these three groups (p>0.05, ANOVA - Tahame). SEM images showed similar bacterial adhesion on the three titanium surfaces, predominantly characterized by cocci and several bacilli, indicating an initial colonization of the oral biofilm. CONCLUSION: In conclusion, roughness and microtopography did not stimulate initial biofilm formation on titanium surfaces with different surface treatments.

Efficiency of low-level laser therapy within induced dental movement: A systematic review and meta-analysis.

The low level laser is widely used in Dentistry, in particular, to decrease pain and increase the speed of tooth movement. This study was to perform a systematic literature search to investigate the effectiveness of low level laser and low energy density therapy of the induced tooth movement. This research was performed following the PRISMA instructions and was registered in the PROSPERO. The articles were searched in six electronic databases, with no date and language restriction. Only randomized clinical trials were selected. Articles that did not use the extraction of first premolars as orthodontic planning were excluded, as well as articles using high energy density laser therapy. The articles were assessed for risk of bias and individual quality. The results were analyzed using meta-analysis, using randomized effect. The initial sample consisted of 161 articles. Six articles remained eligible for qualitative analysis and five for quantitative analysis. According to the individual quality, most articles were classified as high quality. Three articles detected statistically significant differences in induced movement by comparing the orthodontic movement between the experimental and control groups. For the maxilla, there was a statistically significant influence of the laser in three months and, for the mandible, in one month. It may be concluded that there is no evidence that laser therapy can accelerate the induced tooth movement.