Rubens Ferreira de Albuquerque

Alternative Method for Direct DNA Probe Labeling and Detection Using the Checkerboard Hybridization Format

Molecular diagnostic methods using genetic material probes have been employed in the health care field for the detection and quantitation of several species of microorganisms ([2][1], [5][2]). These methods are faster and more suitable than traditional culture methods. In addition, the possibility

The role of enamel crystallography on tooth shade.

OBJECTIVES Tooth shade is influenced by a combination of extrinsic-stains that are adsorbed to the enamel surface and by its intrinsic-shade resulting from the interaction of light with tooth structures. This study was designed to investigate how the variations in enamel ultrastructure may affect tooth optical properties. METHODS One-hundred extracted teeth were collected from adult patients attending McGill-Undergraduate Dental Clinics. Shade-spectrophotometry, FTIR and XRD were used to assess tooth shade, enamel chemical composition and crystallography. The data obtained was analysed for Pearson correlation analysis and multiple linear regression analysis. The statistical significance was set at P < 0.05. RESULTS Tooth shade parameters varied dramatically within the studied population. Pearson correlation analysis demonstrated that tooth hue was associated with enamel hydroxyapatite (HA) crystal size (R = -0.358; B = -0.866; P = 0.007), tooth chroma was associated with enamel HA carbonization (R = -0.419; B = -99.06; P = 0.005), and tooth lightness was associated with both enamel HA crystal size (R = -0.313; B = -1.052; P = 0.019) and the degree of HA carbonization (R = -0.265; B=-57.95; P = 0.033). Multiple linear regression analysis demonstrated that the size of enamel HA crystals and the relative content of mineral carbonate were the most important predictors for tooth shade lightness (P = 0.018) and chroma (P=0.008), respectively. In contrast, enamel organic content had no correlation with tooth shade. CONCLUSIONS In the present study we have revealed that the tooth shade is regulated by the size of their HA enamel crystals. On the other hand, variation in the degree of enamel HA carbonization can also affect the tooth shade. These findings are of great relevance in dentistry since it provides better understanding of tooth aesthetics.

Temporomandibular disorder or Eagle's syndrome? A clinical report

This clinical report describes the diagnosis and treatment of a patient under emotional stress with orofacial pain, headaches, and the feeling of a foreign body in the throat. An elongated styloid process at the beginning of the oral pharynx was diagnosed. Although these symptoms could be aspects of Eagles syndrome, deflective occlusal interferences, tender muscles of mastication, and a clicking temporomandibular joint led to an evaluation for temporomandibular disorder related to malocclusion. An occlusal splint was used to confirm the diagnosis and to alleviate symptoms. Occlusal adjustments were subsequently performed. In a 10-year follow-up, the patient had no complaints.

The outcomes of conservative and surgical treatment of stage 2 bisphosphonate-related osteonecrosis of the jaws: a case series

The purpose of the current retrospective chart review is to describe the outcomes of conservative or surgical treatment of stage 2 bisphosphonate-related osteonecrosis of the jaws (BRONJ). 14 charts (mean patient age 69.07 ± 10.37 years) describing 19 BRONJ stage 2 sites were identified. According to the treatment protocol, all patients received conservative treatment. Surgical treatment was delivered only to sites that did not respond to conservative treatment. Conservative treatment alone was delivered to 11 sites in 8 patients (mean postoperative follow-up 17.6 ± 9.4 months). Surgical treatment was delivered to 8 sites in 6 patients (mean postoperative follow-up 10.0 ± 6.1 months). Bisphosphonate exposure ranged from 1 to 8 years. In most cases, tooth extractions and wearing dentures were reported as triggers for BRONJ. At the last follow-up, BRONJ stage 0 was noted in 7 sites that received conservative treatment and 5 sites that received surgical treatment. Within the limitations of the current chart review, the results showed that although conservative treatment for BRONJ stage 2 can provide favourable outcomes, surgical treatment represents a suitable alternative in non-responsive cases.

Effect of recombinant human bone morphogenetic protein‐2 on bone formation in the acute distraction osteogenesis of rat mandibles

BACKGROUND Distraction osteogenesis (DO) is a method of producing new bone directly from the osteotomy site by gradual traction of the divided bone fragments. AIM The purpose of the present study was to evaluate histomorphometrically whether acute DO would constitute a viable alternative to the conventional continuous distraction treatment and also to verify the capacity of a recombinant human BMP (rhBMP-2) associated with monoolein gel to stimulate bone formation in the acute distraction process. MATERIALS AND METHODS Forty-eight Wistar rats were assigned to three groups: Group 1, treated at a conventional continuous distraction rate (0.5 mm/day), Group 2, treated with acute distraction of 2.5 mm at the time of the surgical procedure, and Group 3, subjected to acute distraction associated with rhBMP-2. The animals from each experimental group were killed at the end of the second or fourth post-operative weeks and the volume fraction of newly formed bone trabeculae was estimated in histological images by a differential point-counting method. RESULTS The results showed that after 2 and 4 weeks, bone volumes in the rhBMP-2 group were significantly higher than in the other groups (P<0.05), but no significant difference was observed in the volume fraction of newly formed bone between the continuous and acute DO groups. CONCLUSION In conclusion, the study indicates that rhBMP-2 can enhance the bone formation at acute DO, which may potentially reduce the treatment period and complications related to the distraction procedure.

Bisphosphonates inhibit bone remodeling in the jaw bones of rats and delay healing following tooth extractions

OBJECTIVE This study aimed to evaluate the impact of concurrent administration of clinically relevant doses of zoledronic acid (ZA) and dexamethasone (DX) on bone healing after tooth extraction (EXO). MATERIALS AND METHODS Forty-four Sprague-Dawley rats (6-8 month old) were randomized into five groups: ZA + DX = weekly injection of ZA with DX for 7 weeks; WD = ZA with DX for 3 weeks then DX alone for 4 weeks; C = control saline for 7 weeks; ZA = ZA alone for 7 weeks and DX = DX alone for 7 weeks. ZA was administered at 0.13 mg/kg/week and DX at 3.8 mg/kg/week and body weights recorded at the time of injection. All rats underwent extraction (EXO) of the mandibular and maxillary first molars at 3 weeks and were euthanized at 7 weeks. The extracted and non-extracted sides of both jaws were harvested for micro-CT analyses. RESULTS All rats, particularly those injected with ZA, exhibited weight gain till EXO followed by decline then recovery. ZA + DX group demonstrated highest fractional bone to tissue volume (BV/TV) in the non-extracted side. ZA + DX rats exhibited also highest volume and surface of sequestra. Only sequestra volume was statistically higher in the WD group compared to C group. CONCLUSION Combined treatment with ZA and DX over a prolonged period inhibits bone remodeling and increased sequestra formation to a greater extent than either drug alone. Trauma caused by these sequestra cutting through the mucosa could play a key role in the development of BRONJ by potentially facilitating infection. ZA withdrawal may promote bone-remodeling reactivation following EXO.

Clinical wear of overdenture ball attachments after 1, 3 and 8 years

OBJECTIVES Implant-supported overdentures have become the treatment of choice in restoring complete edentulism, but the types of attachment to assure durable retention are a subject of debate. Ball attachments were reported as a simple treatment, but wear of components was responsible for a decrease in retention. The aim of this retrospective study was to measure the wear of the ball abutment or patrix after three different periods of clinical wear. MATERIAL AND METHODS Sixty-nine specimens of three groups of patrix that were in use for a mean of 12.3 months (group A), 39 months (group B) and 95.6 months (group C) were retrieved from 35 patients and measured on a coordinate measuring machine equipped with a touch trigger probe. Ten unused ball abutments were added as a control (group D). The patrix diameters and any deviation from circularity in different axes were measured. RESULTS The diameters of groups A, B and C were significantly different from that of group D (control). No statistically significant differences were found between diameter and circularity variations between groups B and C. The maximal amount of diameter reduction was limited to approximately 30 μm, and 90% of diameter loss at the equator due to wear was reached in group B. CONCLUSION One, 3 and 8 years of clinical wear reduced significantly the diameters of the ball abutments tested, and the maximal amount of wear was reached after 3 years of clinical use.

Oral biofilm formation on the titanium and zirconia substrates

OBJECTIVE: The aim of this randomized crossover investigation was to assess the biofilm formation on two titanium and one zirconia substrates in relation to the topography and surface roughness of the materials. METHODS: Twenty‐four discs specimens for each evaluated material (Machined pure titanium, Cast pure titanium, or Zirconia) were evaluated after oral cavity exposure in six healthy subjects. The study was conducted in 3 phases according to the material evaluated. Each subject was asked to use a removable splint containing 4 disks of the same tested substrate, 2 located in the anterior, and 2 in the posterior region. Participants were asked to use the intraoral splint during 24 h. The total biofilm covering on the discs was evaluated by 1% of neutral red staining. EMV and surface roughness was carried out to correlate with the biofilm found between different substrates. RESULTS: Data showed higher mean roughness values for zirconia (Zc) when compared with titanium specimens (MPT and CPT; P < 0.001). MPT and CPT presented no differences between them (P > 0.05). The mean percentage (%) of covering biofilm on substrates was 84.14 for MPT, 86.22 for CPT and 90.90 for Zc. CONCLUSION: There were no significant differences in the total area of formed biofilm among the tested groups. No correlation was found between surface roughness and the total amount of formed biofilm in the groups. Microsc. Res. Tech., 2013.

Impact of temperature and time storage on the microbial detection of oral samples by Checkerboard DNA–DNA hybridization method

PURPOSE Molecular diagnosis methods have been largely used in epidemiological or clinical studies to detect and quantify microbial species that may colonize the oral cavity in healthy or disease. The preservation of genetic material from samples remains the major challenge to ensure the feasibility of these methodologies. Long-term storage may compromise the final result. The aim of this study was to evaluate the effect of temperature and time storage on the microbial detection of oral samples by Checkerboard DNA-DNA hybridization. METHODS Saliva and supragingival biofilm were taken from 10 healthy subjects, aliquoted (n=364) and processed according to proposed protocols: immediate processing and processed after 2 or 4 weeks, and 6 or 12 months of storage at 4°C, -20°C and -80°C. RESULTS Either total or individual microbial counts were recorded in lower values for samples processed after 12 months of storage, irrespective of temperatures tested. Samples stored up to 6 months at cold temperatures showed similar counts to those immediately processed. The microbial incidence was also significantly reduced in samples stored during 12 months in all temperatures. CONCLUSIONS Temperature and time of oral samples storage have relevant impact in the detection and quantification of bacterial and fungal species by Checkerboard DNA-DNA hybridization method. Samples should be processed immediately after collection or up to 6 months if conserved at cold temperatures to avoid false-negative results.

Bacterial Leakage Along the Implant-Abutment Interface

Titanium implants have been successfully and increasingly used for the substitution of dental elements in the treatment of total or partial edentulism, exhibiting success rates frequently above 90%, since the earliest reports on this technique in the 1960 decade (Lang et al., 2004; Pjetursson et al., 2007; Jung et al., 2008). When treatment failures are calculated based on patients who lost implants and not on implant lost by the population in general, success rates may be considerably lower (Lambrecht et al., 2003; Stavropoulos et al., 2007; Esposito et al., 2010). Excessive premature loading, occlusal trauma and poor bone support are considered the main factors associated with early implant loss (Esposito et al., 2000; Piattelli et al., 2003). Recent reports demonstrated that microorganisms in the oral cavity, especially the ones involved in periodontal diseases, together with unfavorable occlusal factors are considered as the main causes of unsuccessful treatment with implants (Mombelli & Lang, 1998; Covani et al., 2006). A direct correlation between presence of microorganisms and disease of the peri-implant tissues has been demonstrated. Gram-negative, anaerobic species like Fusobacterium spp, Prevotella spp and spirochetes are frequently found in large quantities in affected sites. In contrast, healthy sites are predominantly colonized by Gram-positives (Mombelli & Lang, 1998; Quirynen et al., 2006). Periodontitis in proximity to implants and presence of periodontal pathogenic bacteria in the peri-implant sulci are considered risk factors to the success of dental implants (Mombelli et al., 1995; Mombelli & Decaillet, 2011). Surface characteristics, physical properties, as well as biological factors involved in this type of treatment may facilitate bacterial colonization and growth of potentially pathogenic microorganisms at the implant sites (Mombelli et al., 1995; Jansen et al., 1997; Covani et al., 2005). Another risk factor to the peri-implant tissues is the presence of marginal discrepancies between prosthetic crowns and implants abutments, although it is a controversial issue. The assessment of these discrepancies varies largely depending on the material employed for crown fabrication, type of cement, measuring methods, etc. Studies using human extracted teeth have reported marginal discrepancies ranging from 5 to 430 μm (Abbate et al., 1989; Felton et al., 1991; Valderrama et al., 1995; Kosyfaki et al., 2010). The highest values, varying from 110 to 160 μm, are frequently associated to feather–edge cast gold crowns (Marxkors,