Occlusal changes of Class II malocclusion treatment between Fränkel and the eruption guidance appliances

The objective of this study was to compare the occlusal changes of Class II malocclusion treatment provided by two different types of appliances. Group 1 comprised 25 patients treated with the Fr?nkel appliance and group 2 comprised 30 patients treated with the eruption guidance appliance. Evaluations were performed on the initial and final study models of the patients using the peer assessment rating (PAR) index. The final mean PAR index, the mean PAR change, and the percent PAR reduction of each group were compared using the Student's t-test. Results demonstrated that there were no statistically significant differences between the final PAR index, the PAR changes, and the percent PAR reduction of the two groups. Therefore, it was concluded that the occlusal changes provided by the two appliances are similar, as evaluated by the PAR index.     

Physical and mechanical characterization and the influence of cyclic loading on the behaviour of nickel-titanium wires employed in the manufacture of rotary endodontic instruments

AIM: To analyse the influence of cyclic loading on the mechanical behaviour of nickel-titanium (NiTi) wires employed in the manufacture of ProFile rotary endodontic instruments. METHODOLOGY: Nickel-titanium wires, 1.2 mm in diameter, taken from the production line of ProFile rotary endodontic instruments before the final machining step, were tensile-tested to rupture in the as-received condition and after 100 load-unload cycles in the superelastic plateau (4% elongation). The wires were characterized by X-ray energy-dispersive spectroscopy, X-ray diffraction and by differential scanning calorimetry and compared with new size 30, .06 taper ProFile instruments. The fracture surfaces of the wires were observed by scanning electron microscopy. RESULTS: The mechanical properties of the as-received wires, their chemical composition, the phases present and their transformation temperatures were consistent with their final application. Only small changes, which decreased after the first few cycles, took place in the mechanical properties of the cycled wires. The stress at maximum load and the plastic strain at breakage remained the same, while the critical stress for inducing the superelastic behaviour, which is related to the restoring force of the endodontic instruments, decreased by approximately 27%. CONCLUSIONS: The mechanical behaviour of the NiTi wires was modified slightly by cyclic tensile loading in the superelastic plateau. As the changes tended towards stabilization, the clinical use of rotary NiTi ProFile instruments does not compromise their superelastic properties until they fracture by fatigue or torsional overload, or are otherwise discarded.     

Effects of adhesive temperature on the early and 6-month dentin bonding

Objectives

The aim of this study was to test the effect of adhesive temperature on the bond strength to dentin (μTBS) and silver nitrate uptake (SNU) of an ethanol/water (Adper Single Bond 2 [SB]) and an acetone-based (Prime&;Bond 2.1 [PB]) etch-and-rinse adhesive system.

Methods

The bottles of each adhesive were kept in various temperatures (5 °C, 20 °C, 37 °C and 50 °C) for 1 h previously to its application in the occlusal demineralized dentin of 40 molars. Bonded sticks (0.8 mm²) were tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6 M) of water storage. Two bonded sticks from each hemi-tooth were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measures ANOVA and Tukey's test (α = 0.05).

Results

No significant difference in μTBS was detected for both adhesives at 5 °C and 20 °C. The highest bond strength for PB was observed in the 37 °C group while for SB it was in the 50 °C. Significant reductions of bond strengths were observed for PB at 37 °C and SB at 50 °C after 6 M of water storage. Silver nitrate deposition was seen in all hybrid layers, irrespective of the group. Lower silver nitrate deposition (water trees) in the adhesive layer was seen for PB and SB at higher temperatures.

Conclusions

The heating or refrigeration of the adhesives did not improve their resin–dentin bond resistance to water degradation over time.     

Tooth loss and associated risk indicators in an adult urban population from south Brazil

The aim of the present study was to assess the prevalence, extent, and risk indicators of tooth loss in a representative adult, urban population in the Brazilian state of Rio Grande do Sul. A sample of 974 subjects (ages 30 to 103 years, mean 48.7, SD 13.4) representative of the metropolitan area of Porto Alegre, Brazil was selected by a multi-stage probability cluster sampling strategy. In all, 94% of the subjects had experienced tooth loss. The mean tooth loss was 11.2 teeth, and varied between 5.5 and 20.2 teeth in the 30-39 and 60 + years age groups, respectively. The multivariable analysis, adjusted for age, showed that subjects who had lost 7-13 or > or = 14 teeth were more likely to be females (odds ratio (OR) = 1.4, 2.4), of low (OR = 2.8, 5.1) or middle socio-economic status (OR = 2.3, 3.4), and heavy smokers (OR= 2.0, 2.3) than those with 6 or fewer missing teeth. Furthermore, loss of > or = 14 teeth was associated with presence of > 50% teeth with attachment loss > or = 5 mm (OR= 5.7), and loss of 7-13 teeth was associated with presence of > 50% teeth with attachment loss > or = 5 mm (OR = 2.4) and having 15-30% or > 30% decayed-filled teeth (OR = 2.7 and 4.1). In conclusion, tooth loss is highly prevalent in this urban Brazilian population. Gender, socio-economic status, cigarette smoking, caries experience, and attachment loss are important risk indicators. A reduction in the population's tooth loss may be achieved by the implementation of community programs for the prevention and treatment of dental caries and periodontal diseases.     

Recurrence of an ameloblastoma in an autogenous iliac bone graft

A rare case of recurrence of an ameloblastoma in an iliac bone graft many years after the initial operation for a mandibular amelolastoma with evidence of soft tissue invasion is presented. A review of the literature disclosed only 11 cases of recurrence of ameloblastoma in bone grafts. In the case presented the initial operation was a hemimandibulectomy followed by autogenous iliac bone graft. Sixteen years after the surgery there was clinical and radiographic signs of recurrence. It was concluded that extensive resection including bone as well as adjacent soft tissues is critical because the recurrences seem to stem from the soft tissues, especially from the adjacent periosteum.     

Inferior alveolar nerve damage because of overextended endodontic material: a problem of sealer cement biocompatibility?

Damage to the inferior alveolar nerve is a relatively infrequent complication in dental practice. When root canal treatment of a lower molar or premolar surpasses and/or overextends beyond the apical foramen and invades the periapical zone, the foreign material introduced within such a sensitive anatomical space may mechanically or even chemically affect the inferior alveolar nerve. We describe a case of endodontic treatment of a permanent right lower first molar in which the sealer cement overextended in large amounts and damaged the right inferior alveolar nerve. The condition reverted a few months after the surgical removal of the material. Evaluation of the removed material, using powder x-ray diffraction and scanning electron microscopy with coupled dispersive energy spectroscopy, showed it to consist of calcium tungstate (scheelite [CaWO4]) and zirconium oxide (baddeleyite [ZrO2]), which were chemical components of the sealer cement.     

Tooth replantation after traumatic avulsion: a 27-year follow up

Abstract  – This report presents a case of replantation of a traumatically avulsed central incisor in a 32-year-old woman. The tooth was replanted after a 30-min extra-alveolar period. Emergency unconventional immobilization was performed, using 2–0 chromic gut, and a restorative composite made Gunning-type splint. The tooth is still in place 27 years after replantation (1976 to date) without marked resorption.     

Gingival fibrous hamartoma associated with natal teeth

A variety of gingival enlargements can occur in children, but they are rarely observed in the infant. The aim of this study is to present a case of a ten-month old male patient, with an anterior mandibular hamartoma associated to natal teeth, and to describe the clinical and histological characteristics of this anomaly and the treatment performed.     

Caries risk tests and salivary levels of immunoglobulins to Streptococcus mutans and Candida albicans in mouthbreathing syndrome patients

The aim of this study was to compare microbiological and salivary variables possibly related to caries risk in treated and untreated mouthbreathing syndrome (MBS) children and control children. Thirty control children, 30 mouthbreathers and 25 treated mouthbreathers were studied for the numbers of lactobacilli, mutans streptococci and yeasts in their saliva. Snyder's test, salivary flow and buffering capacity were also evaluated. Levels of immunoglobulins to Candida albicans and Streptococcus mutans in the saliva were quantified using ELISA. Considering the results obtained for the microbiological and salivary caries risk tests, no significant differences were observed among the proportions of patients with small/negative and high/moderate caries risk in the studied groups. The level of IgG to S. mutans was significantly higher in the treated MBS group in relation to MBS patients. On the other hand, the median anti-S. mutans IgM level was lower in the treated MBS patients than in the other groups. For the studied anti-Candida immunoglobulins, IgM level was significantly lower in the treated MBS group than in the other groups. No differences were observed for anti-S. mutans and anti-Candida IgA levels among the groups. The findings suggest that mouthbreathing cannot be considered a risk factor for dental caries.     

Tooth loss and subluxation in the primary dentition: a twelve-year follow-up case report

The case of a five-year-old child is reported, who suffered dento-alveolar injury including subluxation of the right upper lateral incisor and avulsion of the upper central incisors and left upper lateral incisor and laceration in the mucosa. The case was followed for 12 years until complete root formation and alignment of the anterior permanent teeth.