Ana Christina Claro Neves

Urinary levels of catecholamines among individuals with and without sleep bruxism

IntroductionSleep bruxism (SB) is characterized by repetitive and coordinated mandible movements and non-functional teeth contacts during sleep time. Although the etiology of SB is controversial, the literature converges on its multifactorial origin. Occlusal factors, smoking, alcoholism, drug usage, stress, and anxiety have been described as SB trigger factors. Recent studies on this topic discussed the role of neurotransmitters on the development of SB.ObjectiveThus, the purpose of this study was to detect and quantify the urinary levels of catecholamines, specifically of adrenaline, noradrenaline and dopamine, in subjects with SB and in control individuals.Materials and methodsUrine from individuals with SB (n = 20) and without SB (n = 20) was subjected to liquid chromatography. The catecholamine data were compared by Mann–Whitney’s test (p ≤ 0.05).ResultsOur analysis showed higher levels of catecholamines in subjects with SB (adrenaline = 111.4 µg/24 h; noradrenaline = 261,5 µg/24 h; dopamine = 479.5 µg/24 h) than in control subjects (adrenaline = 35,0 µg/24 h; noradrenaline = 148,7 µg/24 h; dopamine = 201,7 µg/24 h). Statistical differences were found for the three catecholamines tested.ConclusionIt was concluded that individuals with SB have higher levels of urinary catecholamines.

Stability of external and internal implant connections after a fatigue test

Objective: The objective of this study was to compare the torque and detorque values of screw intermediates of external hexagon, internal hexagon, and Morse taper implants in single restorations before and after mechanical cycling. Materials and Methods: The study sample was divided into three groups (n = 10) as follows: group EH - external hexagon implant, group IH - internal hexagon implant, and group MT - Morse taper implant. Universal abutments were screwed on the implants, and metal crowns were cemented onto the abutment. The samples were submitted to a mechanical testing of 1 million cycles, with a frequency of 8 cycles per second under a 400 N load. The application and registration of the screw torque (T0) and detorque (T1) values of the intermediate were performed before and after the test. The results were statistically evaluated by analysis of variance (ANOVA) and Tukey′s test (α = 0.05). Results: There was no difference between the values of T0 and T1 in the intra-group samples. However, the inter-group difference in T0 between the EH (12.8 N cm) and MT (18.6 N cm) groups and in T1 between the EH (10.4 N cm) and IH (13.8 N cm), EH and MT (19.4 N cm), and MT and IH (P = 0.001) groups were significant. The MT group showed a lower variation of T0 and T1. Conclusion: The internal implants, particularly MT, showed better stability in these cases when used for single restorations.

Evaluation of the etiology of ocular globe atrophy or loss

This survey investigated the etiology of atrophy or loss of the ocular globe in patients assisted at the Maxillofacial Prosthetics Clinic of two Schools of Dentistry in São Paulo State, Brazil. A total of 238 patients were examined and their clinical files were reviewed. The etiology of eyeball atrophy/loss was assessed with respect to gender, age group, affected side and type ophthalmologic surgery performed. The greatest incidence of ocular globe loss was due to traumatic etiology (57.14%), followed by pathogenic (36.13%) and congenital (5.04%) etiologies. Comparing the genders, a predominance of male patients was observed (61.76%; p<0.01). The age group most frequently affected was between 21 and 40 years (42.01%; p<0.01). For all types of etiologies investigated in this study, enucleation was the most commonly used surgical procedure for removal of the ocular globe (66.38%; p<0.01). Loss of the left eye was predominantly seen (55.04%), even though no statistically significant difference was found between sides (p>0.01).

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.

Evaluation of the accuracy of different transfer impression techniques for multiple implants

The aim of this study was to evaluate the accuracy of three implant transfer impression techniques. Four groups (n = 5) were defined, according to the technique: TC - tapered copings without splint; SC - square copings without splint; SCS - square copings splinted with dental floss and acrylic resin, and CG (control group) - master model with four external hexagonal implants and a superstructure. Individual trays and polyether were used for the impression. All casts were checked for their fit into the master superstructure; for this, all four screws were placed in the implants. Digital photos were taken and images were analyzed using UTHSCSA ImageTool software. Statistical analyses were performed using one-way analysis of variance and Students t test (p < 0.05). The means and standard deviation were (µm): CG = 2.03 ± 0.00, TC = 14.74 ± 3.41, SC = 12.08 ± 2.56, and SCS = 6.51 ± 0.09. The control group was found to be statistically different from the TC and SC groups. Within the limitations of this study, all groups presented clinically acceptable standard gap values, and the SCS group showed no statistical difference in relation to the CG (control group), demonstrating more accuracy and fidelity to transfer implants.

DESENVOLVIMENTO DE UMA ESCALA EM SILICONA PARA TONS DE PELE HUMANA

The author developed a scale in silicone of shades of human skin. Twenty-seven samples were produced in acetic silicone (Silastic 732 RTV), pigmented with iron oxides and titanium dioxide. The amount of acetic silicone was kept constant (two grams) in all of the samples, and the pigments were mixed to it in varying proportions, until twenty-seven different shades were obtained. By comparing the color of the samples with the skin color of forty-one individuals, five samples were selected of the shades that best matched a patients color of skin to form a shade guide. With the methodology employed, it was possible to develop a shade guide that will facilitate a definition of a patients skin color in producing facial prostheses in silicone, to afford economy in time and in material at time for selecting the color.

Influence of anatomic reference on the buccal contour of prosthetic crowns

During clinical practice, when performing prosthetic rehabilitation with single crowns, improper reproduction of the dental contour by the dental laboratory is a common occurrence. Therefore, the present study evaluated the fidelity of the reproduction of the buccal contour in an upper left canine performed by three Dental Prosthesis Technicians (DPT) using the indirect laminate veneer technique. First, the DPTs confected the veneers based on a model obtained from the upper arch of a dental dummy, containing a replica of an upper left canine with a prosthetic preparation for a laminate veneer. Then, the same DPTs received other identical models, now with the replica of the upper left canine with no preparation, to be used as an anatomical reference for confecting the laminate veneers. The laminate veneers were then bonded to the plaster models and had their buccal contour individually measured. Measurements were also made of the buccal contour of the reference canine. The data were analyzed by ANOVA and the t-test (p = 0.05). Results showed 100% of buccal overcontour when the laminate veneers were compared to the reference canine, regardless of which DPT confected the veneer and regardless of using or not the anatomical reference. The DPTs who participated in the present study were unable to acomplish a faithful anatomical reproduction of the buccal contour, creating an overcontour in all samples. This situation may be responsible for increasing the probability of periodontal and esthetic harm in clinical practice.

Effect of interim cement application on bond strength between resin cements and dentin: Immediate and delayed dentin sealing

Statement of problem Despite the advances in materials and techniques, adhesion to dentin is challenging because of the complex composition of dentin’s mineral, organic, and fluid phases. Purpose The purpose of this in vitro study was to evaluate the bond strength of 2 different resin cements (conventional and self‐adhesive) with or without previous dentin sealing and the effect of interim cement. Material and methods Forty‐five molars were embedded into acrylic resin blocks and a flat dentin surface was exposed. Twenty teeth (n=5 per group) were treated with the conventional resin cement associated with etch‐and‐rinse or self‐etch adhesive approaches, applied before (immediate dentin sealing) or after (delayed dentin sealing) the application/removal of interim cement. Another 25 teeth (n=5, per group) were treated with self‐adhesive resin cement with (self‐etch mode [immediate dentin sealing or delayed dentin sealing]) or without adhesive application. Furthermore, in the self‐adhesive resin cement group, the application of polyacrylic acid for dentin etching before cementation was evaluated. Composite resin blocks were cemented onto flat, treated dentin surfaces, and the assemblies were sectioned into bar‐shaped specimens for microtensile bond strength testing. The data were subjected to 1‐way ANOVA followed by the post‐hoc Tukey test (&agr;=.05). The failure patterns were classified as cohesive, adhesive, or mixed. Results The application of adhesive before interim cement (immediate dental sealing) promoted the highest values of bond strength for both resin cements (P<.001). For self‐adhesive resin cement, polyacrylic acid‐enhanced bond strength after the application of interim cement. Conclusions The application of dental adhesive immediately after tooth preparation (immediate dentin sealing) and before the use of an interim cement promoted the highest values of bond strength to dentin with the resin cements tested.

Effect of polymerization method and fabrication method on occlusal vertical dimension and occlusal contacts of complete-arch prosthesis

PURPOSE This study evaluated the dimensional stability of a complete-arch prosthesis processed by conventional method in water bath or microwave energy and polymerized by two different curing cycles. MATERIALS AND METHODS Forty maxillary complete-arch prostheses were randomly divided into four groups (n = 10): MW1 - acrylic resin cured by one microwave cycle; MW2 - acrylic resin cured by two microwave cycles: WB1 - conventional acrylic resin polymerized using one curing cycle in a water bath; WB2 - conventional acrylic resin polymerized using two curing cycles in a water bath. For evaluation of dimensional stability, occlusal vertical dimension (OVD) and area of contact points were measured in two different measurement times: before and after the polymerization method. A digital caliper was used for OVD measurement. Occlusal contact registration strips were used between maxillary and mandibular dentures to measure the contact points. The images were measured using the software IpWin32, and the differences before and after the polymerization methods were calculated. The data were statistically analyzed using the one-way ANOVA and Tukey test (α = .05). RESULTS he results demonstrated significant statistical differences for OVD between different measurement times for all groups. MW1 presented the highest OVD values, while WB2 had the lowest OVD values (P<.05). No statistical differences were found for area of contact points among the groups (P=.7150). CONCLUSION The conventional acrylic resin polymerized using two curing cycles in a water bath led to less difference in OVD of complete-arch prosthesis.

Three-dimensional finite element analysis of occlusal splint and implant connection on stress distribution in implant–supported fixed dental prosthesis and peri-implantal bone

The aim of this study was to investigate the influence of occlusal splint therapy on the stress distribution of implant-supported fixed dental prosthesis (FDP) and peri-implantal bone structures using three-dimensional (3D) finite element analysis (FEA). The system consisted of two implants (positioned on region of second premolar and second molar) as retainers of fixed porcelain-fused-to-metal 3-unit FDP (first molar as pontic element). Two implant connections systems (external and internal hexagon) were tested. Static axial loads simulating functional (100N) and overloaded (300N) chewing were applied on the occlusal surface of the FDP covered or not with the occlusal splint. Maximum von Mises stress and bioperformance were accessed for the implants and bone tissues (cortical and cancellous) models. Analytic results indicated that independently of the load condition, implant region, and connection type, the presence of the occlusal splint decreased the stress developed in the implants. Both bone tissues showed increased levels of von Mises stress, and the bioperformance index was far from their maximum yield strength. The internal hexagon implants presented lower stress on premolar and molar regions than external hexagon implants under functional load and overload. The presence of the occlusal splint device over implant-supported FDP may be clinically useful for forwarding stresses towards the bone structure to maintain implants for long term.