Microwave-induced fast decalcification of rat bone for electron microscopic analysis: An ultrastructural and cytochemical study

Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4oC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37°C. In the first day, the specimens were irradiated 9 times and stored at 40°C overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.

Influence of microwave polymerization method and thickness on porosity of acrylic resin

Purpose: This study evaluated the influence of polymerization cycle and thickness of maxillary complete denture bases on the porosity of acrylic resin. Materials and Methods: Two heat-activated denture base resins - one conventional (Clássico) and one designed for microwave polymerization (Onda-Cryl) - were used. Four groups were established, according to polymerization cycles: A (Onda-Cryl, short microwave cycle), B (Onda-Cryl, long microwave cycle), C (Onda-Cryl, manufacturing microwave cycle), and T (Clássico, water bath). Porosity was evaluated for different thicknesses (2.0, 3.5, and 5.0 mm; thicknesses I, II, and III, respectively) by measurement of the specimen volume before and after its immersion in water. The percent porosity data were submitted to Kruskal-Wallis for comparison among the groups. Results: The Kruskal-Wallis test detected that the combinations of the different cycles and thicknesses showed significant differences, and the mean ranks of percent porosity showed differences only in the thinnest (2.0 mm) microwave-polymerized specimens (A = 53.55, B = 40.80, and C = 90.70). Thickness did not affect the results for cycle T (I = 96.15, II = 70.20, and III = 82.70), because porosity values were similar in the three thicknesses. Conclusions: Microwave polymerization cycles and the specimen thickness of acrylic resin influenced porosity. Porosity differences were not observed in the polymerized resin bases in the water bath cycle for any thickness. © 2007 by The American College of Prosthodontists.

Prevalence of dental trauma in patients with cerebral palsy

This study presents the findings of a record review that evaluated the prevalence of dental trauma in patients with cerebral palsy and evaluated its possible relationship with age, type of palsy, and epilepsy. The dental records of 2,200 patients with special needs admitted to the special care clinic of the School of Dentistry of Araçatuba/UNESP, Brazil, between 1998 and 2003 were reviewed. Of the records that were analyzed, 500 patients who had cerebral palsy were selected for this study. Information regarding age, gender, type of palsy and dental trauma was collected and statistically analyzed. It was observed that 10.6% of the subjects (n = 53) had sustained dental trauma. The number of traumatized teeth was 84. Enamel or enamel/dentin fractures were the most frequent types of traumatic injury (84.9%). The permanent maxillary central incisors were the most commonly affected teeth (50%). The frequency of traumatic injuries showed no significant correlation (p>.05) with the type of cerebral palsy or gender and they were more frequent in subjects between the ages of 0 and 12 years. Having epilepsy was not a statistically significant risk factor (p>.05) for dental trauma. © 2008 Special Care Dentistry.

Ossificação da sutura palatina mediana após o procedimento de expansão rápida da maxila: Estudo radiográfico

Objective: the current study aims at following up radiographically the evolution of the midpalatal suture during the expansion procedure since the opening of the suture until bone formation. Methods: the sample comprised 38 patients in the mixed dentition stage submitted to the rapid palatal expansion protocol of the Hospital for Rehabilitation of Craniofacial Anomalies. Results: it was observed an individual variation on the period of bone ossification of the midpalatal suture, which justifies the radiographic follow-up as determinant for the appliance removal. Due to long-term post-treatment stability, the expander should be removed after the new suture is completely formed. Conclusions: the findings show that it is necessary more than three months for the complete reorganization of the midpalatal suture during the passive phase of the rapid palatal expansion.

Excision of an atypical case of palatal bone exostosis: a case report.

Bone exostosis has long been described in the literature, appearing in most cases as a torus palatinus or mandibularis. These two variations are relatively common and affect approximately 30% of the world's population. Incidence is even higher when human skulls are examined post mortem, indicating that in some cases the exostosis is small and cannot be seen under the soft tissue. Removal of an exostosis is usually associated with the construction of a prothesis, but in rare cases such as the present, the lesion enlarges enough to affect speech and feeding. Few studies have reported the removal of such a large exostosis, and all were conducted in a hospital environment. In this case, complete removal was successfully conducted in an ambulatory clinic under local anesthesia.

In vitro assessment of pulp chamber temperature of different teeth submitted to dental bleaching associated with LED/laser and halogen lamp appliances

This study sought to assess the pulp chamber temperature in different groups of human teeth that had been bleached using hydrogen peroxide gel activated with halogen lamps or hybrid LED/laser appliances. Four groups of ten teeth (maxillary central incisors, mandibular incisors, mandibular canines, and maxillary canines) were used. A digital thermometer with a K-type thermocouple was placed inside pulp chambers that had been filled with thermal paste. A 35% hydrogen peroxide-based red bleaching gel was applied to all teeth and photocured for a total of three minutes and 20 seconds (five activations of 40 seconds each), using light from an LED/laser device and a halogen lamp. The temperatures were gauged every 40 seconds and the data were analyzed by three-way ANOVA, followed by Tukey's test. Regardless of the light source, statistically significant differences were observed between the groups of teeth. The mean temperature values (±SD) were highest for maxillary central incisors and lowest for mandibular canines. The halogen lamp appliance produced more pulp chamber heating than the LED/laser appliance. The increase in irradiation time led to a significant increase in temperature.

Dual path: A concept to improve the esthetic replacement of missing anterior teeth with a removable partial denture

The dual path of insertion concept for removable partial denture (RPD) design may be used in esthetically demanding situations. When compared to conventional RPDs, the main advantage of this design is the minimal use of clasps. This clinical report describes the treatment of a patient with an anterior maxillary edentulous area using a dual path RPD. The diagnostic cast was surveyed to ensure the adequacy of the undercuts on the mesial surfaces of the anterior abutments, where rigid minor connectors were placed. Inverted V-shaped canine cingulum rest seats were prepared to provide resistance to tooth movement during function. The dual path RPD concept allows excellent esthetic results, minimizes tooth preparation, and reduces the tendency toward plaque accumulation in a Kennedy class IV partially edentulous arch. © 2008 by The American College of Prosthodontists.

Orthognathic Surgery in the Young Cleft Patient: Preliminary Study on Subsequent Facial Growth

Purpose: This study evaluated the long-term effects of orthognathic surgery on subsequent growth of the maxillomandibular complex in the young cleft patient. Patients and Methods: We evaluated 12 young cleft patients (9 male and 3 female patients), with a mean age of 12 years 6 months (range, 9 years 8 months to 15 years 4 months), who underwent Le Fort I osteotomies, with maxillary advancement, expansion, and/or downgrafting, by use of autogenous bone or hydroxyapatite grafts, when indicated, for maxillary stabilization. Five patients had concomitant osteotomies of the mandibular ramus. All patients had presurgical and postsurgical orthodontic treatment to control the occlusion. Radiographs taken at initial evaluation (T1) and presurgery (T2) were compared to establish the facial growth vector before surgery, whereas radiographs taken immediately postsurgery (T3) and at longest follow-up (T4) were used to determine postsurgical growth. Each patient's lateral cephalograms were traced, and 16 landmarks were identified and used to compute 11 measurements describing presurgical and postsurgical growth. Results: Before surgery, all patients had relatively normal growth. After surgery, cephalograms showed statistically significant growth changes from T3 to T4, with the maxillary depth decreasing by -3.3° ± 1.8°, Sella-nasion-point A by -3.3° ± 1.8°, and point A-nasion-point B by -3.6° ± 2.8°. The angulation of the maxillary incisors increased by 9.2° ± 11.7°. Of 12 patients, 11 showed disproportionate postsurgical jaw growth. Maxillary growth occurred predominantly in a vertical vector with no anteroposterior growth, even though most patients had shown anteroposterior growth before surgery. The distance increased in the linear measurement from nasion to gnathion by 10.3 ± 7.9 mm. Four of 5 patients operated on during the mixed dentition phase had teeth that erupted through the cleft area. A variable impairment of postoperative growth was seen with the 2 types of grafting material used. No significant difference was noted in the effect on growth in patients with unilateral clefts versus those with bilateral clefts. The presence of a pharyngeal flap was noted to adversely affect growth, whereas simultaneous mandibular surgery did not. After surgery, 11 of 12 patients tended toward a Class III end-on occlusal relation. Conclusions: Orthognathic surgery may be performed on growing cleft patients when mandated by psychological and/or functional concerns. The surgeon must be cognizant of the adverse postsurgical growth outcomes when performing orthognathic surgery on growing cleft patients with the possibility for further surgery requirements. Performing maxillary osteotomies on cleft patients would be more predictable after completion of facial growth. © 2008 American Association of Oral and Maxillofacial Surgeons.

Influence of local tetracycline on the microbiota of alveolar osteitis in rats

The aim of the present study was to evaluate the effects of local tetracycline on the occurrence of alveolar osteitis in rats, and on the microbiota associated to this infection. Forty Wistar rats were randomly assigned to 4 groups (n=10): I - the rats had the maxillary right incisor extracted and the alveolar wound did not receive any treatment; II - adrenaline and Ringer-PRAS were introduced into the alveolar wound; III - the alveolar wound was irrigated with sterile saline; and IV - the alveolar wound was irrigated with an aqueous solution of tetracycline. Microbial samples from the alveolar wounds were collected 2 days after surgery and inoculated on blood agar (with and without 8 μg/mL of tetracycline) and other selective media, and were incubated in either aerobiosis or anaerobiosis at 37°C, for 2 to 14 days. It was verified that tetracycline reduced the occurrence of alveolar osteitis in the rats and caused significant changes in the microbiota of the surgical sites, decreasing the number of anaerobes and increasing the participation of tetracycline-resistant and multi-resistant microorganisms.

Conservative management of severe intrusion in a primary tooth: A 4-year follow-up

The purpose of this report was to describe the case of an 18-month-old boy who was referred to the pediatric clinic of the School of Dentistry of Araçatuba, São Paulo State University, Araçatuba, São Paulo, Brazil, 3 days after sustaining severe trauma that led to the complete intrusion of the primary maxillary right lateral incisor, a crown fracture of the primary maxillary right central incisor without pulp involvement, and disruption of the superior labial frenum. Four months later, spontaneous re-eruption was observed in the intruded tooth and no endodontic intervention was necessary in either traumatized teeth. Four years after the trauma, a morphological change in the germ of the permanent successor was noted. Clinical follow-up and periodic radiographies are necessary after traumatic intrusion of primary teeth to monitor possible sequelae in the permanent successors.

Efeito da ingestão crônica de álcool na progressão de periodontite induzida em ratos da linhagem Fischer-344

Objective: Understand the effect of chronic alcohol on the progression of periodontitis induced in Fischer-344 rats. Methods: For the study, 22 Fischer-344 rats, two months old were used, divided into groups: alcohol (n=8), ligature (n=7) and control (n=7). On the first day, the animals in the alcohol group were exposed to ingestion of a water solution containing 20% alcohol (size/size), up to day 90. After thirty days from the beginning of the experiment, the animals in the alcohol group and the ligature group were submitted to the placement of a silk thread around the right maxillary second molar. Nothing was performed on the left side, serving as control. All the groups were submitted to euthanasia 60 days after ligature placement. To assess the destruction of periodontitis, a radiographic exam was used to measure the destruction of bone height. Results: The results of the study showed that on the side in which periodontitis was induced, the group that ingested alcohol suffered an increase in destruction, with statistical differences when compared with the ligature and control groups and increased bone destruction in the ligature group when compared to control. Conclusion: Within the limitations of the study, it was concluded that chronic alcohol consumption by Fischer-344 rats led to greater progression of induced periodontitis.

Digital versus conventional radiography for determination of primary incisor length

Aim: This in vitro study evaluated the accuracy of primary incisor lengths determined by digital and conventional radiography compared to the actual tooth length. Methods: Twenty extracted primary maxillary incisors were mounted in acrylic blocks. Tooth length was estimated by using a straight-line measurement provided by the distance measurement tool of a digital dental imaging system (Computed Dental Radiography, Schick Technologies Inc.) and conventional E-speed film radiographs by using a digital caliper. Two operators familiar with both radiographic methods performed the estimates. The estimated tooth lengths were compared to the actual tooth lengths measured with the digital caliper. Data were statistically analyzed by Dahlberg's equation, paired t test, Pearson's correlation coefficient and ANOVA at 5% significance level. Results: There were no statistically significant differences (p = 0.85) between tooth length estimated on digital and conventional radiographs. Admitting as clinically acceptable a 0.5-mm discrepancy between the actual tooth lengths and the radiographically estimated lengths, 60% of the radiographic measurements were considered as accurate. When the acceptable difference range was 1.0 mm, the accuracy of the radiographic measurements increased to 100%. Conclusions: Digital and conventional radiography provided similar tooth length measurements and were equivalent to the actual tooth lengths.

Low caloric value of ethanol itself increases alveolar bone loss in ligature-induced periodontitis in male rats

This study aimed at morphometrically evaluating the influence of variable caloric values of ethanol consumption on alveolar bone loss in periodontitis in male rats. Thirty-six male rats were randomized into four groups of nine rats each, as follows: Test group A (low) - rats were fed an ethanol-containing liquid diet (ethanol representing 22% of total caloric value); Control group A - rats were fed a pair-fed control diet (ethanol replaced by isocaloric amounts of carbohydrate); Test group B (high) - rats were fed an ethanol-containing liquid diet (ethanol representing 36% of total caloric value); Control group B - rats were fed a pair-fed control diet for Test B. Following anesthesia, cotton ligatures were placed around the cervix of the right upper second molar. At eight weeks, the maxillary bones were removed and alveolar bone loss was analyzed by measuring the distance between the cementoenamel junction and the alveolar bone crest at buccal and palatal sites of the upper second molar. The unligated groups showed no significant differences between the bone loss values observed for the low and high caloric values of ethanol (p > 0.05). In the ligated groups, the rats receiving low caloric values of ethanol showed significantly greater bone loss compared to the isocaloric rats (p < 0.05); however, the rats receiving high caloric values of ethanol showed no significant differences compared to the controls. Analysis of the results demonstrated that, in male rats, ethanol itself affected ligature-induced bone loss when representing a low value in the total caloric value.

Inter-relação entre o perfil dos lábios superiores e a posição da maxila e dos incisivos superiores em pacientes adultos

Introduction: Professional evaluations and lay person evaluations as well do not show a clear relationship between hard tissue and soft tissue profiles in orthodontic patients. However, there are concrete evidences that the orthodontist can change the facial profile of the patients. aim: This research project aimed to measure the contribution of the bone structure of the maxilla and the upper incisors inclination to the upper lip profile. Methods: A sample of 147 adult patients, 58 male and 89 female, aged from 15 to 49 years, the most of them Caucasians, was retrospectively selected from the private practice of one of the authors. It was assumed that the esthetic facial profile depends of the hard tissues that support it besides its own features as thickness, strength and composition. The present research model was not set to control the intrinsic features of the soft tissue. To compose the Ricketts and Burstone esthetic lines, the main cephalometric variables were SNA and U1PP, when concomitantly considered. Results: The regression coefficients, although statistically significant, did not contributed expressively to explain the regard variables, the pre-defined esthetic lines. Furthermore, the results suggested a negative correlation between the maxillary position (SNA) and the anteroposterior inclination of the upper incisors (U1PP), possibly due to the compensatory action of the lips and the tongue. Conclusion: The results did not presented conclusive scientific evidences about the contribution of the hard tissues for the soft tissue facial profiles.

Cone-beam computed tomography analysis of the apical third of curved roots after mechanical preparation with different automated systems

The present study evaluated by cone-beam computed tomography (CBCT) the apical canal transportation and centralizing ability of different automated systems after root canal preparation. The mesiobuccal canals of maxillary first molars (n=10 per group) were prepared with: GI - reciprocating system with K-Flexofile; GII - reciprocating system with NiTiFlex files; GIII - rotary system with K3 instruments; GIV - rotary system with RaCe instruments. CBCT scans were taken before and after biomechanical preparation up to a #40.02 diameter. Canal transportation was determined by measuring the smallest distance between the inner canal walls and the mesial and distal sides of the root. The centralization ability corresponded to the difference between the measurements from transportation evaluation, using the linear voxel to voxel method of analysis. The mean transportation was 0.06 ± 0.14 mm, with a tendency to deviate to the mesial side of the root (n=22), with no statistically significant difference among the groups (p=0.4153). The mean centralization index was 0.15 ± 0.65 also without statistically significant difference among the groups (p=0.0881). It may be concluded that apical canal transportation and centralization ability were not influenced by the type of mechanical movement and instruments used.