Influence of calcium hydroxide intracanal dressings on the prognosis of teeth with endodontically induced periapical lesions

AIM: This prospective clinical study explored the influence of calcium hydroxide as an interappointment dressing on the healing of periapical lesions associated with pulpless teeth that had not been endodontically treated previously. This was achieved by comparing the prognosis after a two-visit root canal treatment with that following a one-visit treatment. METHODOLOGY: Seventy-three patients were recruited having one tooth with an endodontically induced lesion. Of these patients, 67 could be re-examined. Calcium hydroxide was placed in the instrumented root canals of 31 teeth for at least one week and the treatment finished at the second visit. Thirty-six teeth were root canal treated at one visit. The criteria for success were the absence of signs and symptoms indicating an acute phase of periapical periodontitis and radiographically a periodontal ligament space of normal width. Methods for event time analysis were used to evaluate and compare the prognosis of both treatment approaches. RESULTS: The probability that complete periapical healing will take place increased continuously with the length of the observation period. In both treatment groups the likelihood that the root canal treatment yields a success within an observation time of five years exceeded 90%. A statistically significant difference between the two treatment groups could not be detected. CONCLUSIONS: From a microbiological perspective, one-visit root canal treatment created favourable environmental conditions for periapical repair similar to the two-visit therapy when calcium hydroxide was used as antimicrobial dressing. One-visit root canal treatment is an acceptable alternative to two-visit treatment for pulpless teeth associated with an endodontically induced lesion.     

Microleakage of four Class II resin composite insertion techniques at intraoral temperature.

Twenty recently extracted human molars had standardized Class II slot cavities prepared on the mesial and distal surfaces with the gingival floor located on dentin. The teeth were embedded in a stone template, warmed to 37 degrees C, and restored immediately using one of two incremental placement techniques with visible light-cured composite (VLC), or one of two directed shrinkage placement techniques using an autocure/VLC composite combination. Teeth were stored at 37 degrees C for 2 weeks, thermocycled, stained, sectioned in the middle of the preparation, and evaluated for dye penetration. Reevaluation of the microleakage following removal of the resin composite from the preparation revealed greater microleakage at the gingival margin than did the initial sectioning technique. There were no differences among any of the groups. Enamel margins exhibited minimal leakage and no differences among the groups.     

Analysis of strain gage method for measurement of post-gel shrinkage in resin composites.

OBJECTIVE: The objective of this study was to refine a strain gage method for measuring polymerization contraction of resin composites and to isolate the net post-gel contraction by identifying factors contributing to the measured strains. The hypothesis to be tested was that carefully controlled strain gage measurements of composite polymerization could isolate post-gel contraction events. METHODS: Composite was placed on a biaxial strain gage and light-cured. This method enabled real-time registration of the progress of shrinkage strain, corresponding to elastic modulus development. Strain from the two axes of the strain gage were averaged and plotted as a function of time. A representative curve was calculated from the mean of ten measurements. The following factors influencing the total contraction measurement were evaluated: thermal expansion of the gage, thermal expansion of the composite due to the exothermic reaction and exposure to the curing light, and adhesion of the composite to the gage. These parameters were measured so that the net deformation of the composite during polymerization could be calculated. RESULTS: Parametric studies of pre-cured and photointiator-free materials confirmed the hypothesis that strain gages measure post-gel contraction. Thermal artifacts were measured and subtracted from the total strain output. SIGNIFICANCE: Strain gages are suitable for measuring the clinically significant phase of composite polymerization contraction.     

Mechanical frequency and stimulation-site-related differences in vibrotactile detection capacity along the lip vermilion in young adults

Accurate clinical assessment of the infraorbital and mental branch of the trigeminal nerve is aided by an appreciation of the variations in sensitivity that may exist along the surface of the perioral region under examination. The purpose of this investigation was to map the mediolateral spatial and frequency variations in vibrotactile detection capacity to inputs delivered to the upper lip (UL) and lower lip (LL) vermilion. Mechanical vibrotactile inputs at frequencies of 5, 10, 50, and 150 Hz were delivered to three locations on the vermilion of the UL and LL: midsagittally and laterally (left and right) at a point halfway between the midsagittal plane and the oral angle. An adapted staircase tracking method was used to converge upon a threshold value for each test frequency at each stimulation site. The results indicated that midsagittal vermilion sites were significantly more sensitive to our range of vibrotactile inputs compared to lateral vermilion locations. In addition, no significant differences in sensitivity as a function of laterality or between the UL and LL vermilion sites were noted. Greater midline sensitivity to vibrotactile stimulation suggests that receptive fields at this location may be of greater density and/or demonstrate greater overlap compared to lateral vermilion sites. Both investigators contributed equally to this report and should be considered co-first authors.     

Anterior mandibular apical base augmentation in the surgical orthodontic treatment of mandibular retrusion

The authors describe a surgical technique alternative to traditional pre-surgical orthodontics in order to increase the apical base in mandibular retrusion (class II, division I). This subapical osteotomy, optimizing inferior incisal axis without dental extractions and a long orthodontic treatment, associated to genioplasty permits to obtain an ideal labio-dento-mental morphology. This procedure avoids in some cases the need of a mandibular advancement and, if necessary, it reduces his entity with obvious advantages.     

Salivary thromboplastic activity in diabetics and healthy controls

Coagulative function of saliva derives from the thromboplastin found in saliva. It may establish hemostasis in the mouth. Salivary disfunction and changes in salivary composition and are frequent complications of diabetes. This study investigated the influence of some local etiologic and systemic factors on salivary thromboplastic activity (STA) in diabetics. In this study, cytological smears and biochemical tests were used. STA was measured by Quicks one stage method, serum glucose by the glucose oxidase method, and salivary protein by the method of Lowry. STA was almost the same in the diabetic and control groups. The only statistically significant difference within the diabetic group was found to be due to antibiotic usage. STA, i.e. clotting time, was 30% longer (114 s) (p<0.05) and salivary protein (4.07 mg ml^-1) (p<0.1) was lower in diabetics not taking antibiotics than in those taking them. No such differences were observed in the healthy controls. Significant linear correlations (p<0.05) with respect to STA were with salivary protein in the control group (r=0.61) and in the diabetic group (r=0.51) and with antibiotic usage (r=0.29), with leukocyte cell count (r=0.27) in the diabetic group. It can be concluded that salivary cells, proteins and antibiotic usage are important for STA.     

Effects of induced periapical abscesses on rat pregnancy outcomes

Objective

The objective of this study was to determine the effects of induced periapical abscesses on pregnant rats.

Design

In 1/2 of the animals (n = 16), the pulps of the maxillary right molars were exposed to the oral environment, which resulted in a periapical abscess. The other 1/2 (n = 16) were sham-operated. 1/2 of the animals of both groups became pregnant 2 weeks later. The pregnancy duration, and weight and number of pups were assessed at delivery. Serum, liver and uterine horn samples were taken from all animals at euthanasia and serum IL-6, endothelin-1, TNF-α, IL-10, cortisol and insulin were determined by ELISA. Liver concentrations of IL-6, CRP and IL-6 and uterine horn concentrations of IL-6, vascular endothelial growth factor (VEGF), TNF-α, IL-10 and IL-1-β were assessed by ELISA. Blood glucose concentrations were determined using a glucometer. Outcome variables were compared by factorial ANOVA, a post hoc Tukey test, and Pearson’s correlation test.

Results

Pregnant rats with periapical abscesses had a significantly longer pregnancy and delivered pups with a significantly higher birthweight (p < 0.05). They had significantly higher concentrations of IL-6, VEGF, IL-1-β, and IL-10 within the uterine horn and IL-6, CRP and TNF-α within the liver (p < 0.01). Blood glucose and serum TNF-α, IL-6, endothelin-1, IL-10, and insulin concentrations were significantly higher in the pregnant animals with pulpal abscesses (p < 0.01).

Conclusion

The significant increase in serum TNF-α, taken together with significant increases in blood glucose and serum insulin concentrations, suggest that animals with induced periapical abscesses developed insulin resistance, which significantly affected their pregnancy outcomes.     

Influence of human dentine on the antibacterial activity of self-etching adhesive systems against cariogenic bacteria

OBJECTIVES: The incorporation of antibacterial agents into adhesive systems has been proposed to eliminate residual bacteria from dentine. This study used the agar diffusion method to evaluate the antibacterial activity of Clearfil Protect Bond (CPB), Clearfil SE Bond (CSEB), Clearfil Tri-S Bond (C3SB) and Xeno-III (XIII) self-etching adhesive systems, with or without light-activation, against cariogenic bacteria, and to assess the influence of human dentine on the antibacterial activity of these materials. METHODS: An aliquot of 10 microl per material (and individual components) were pipetted onto paper and dentine discs distributed in Petri dishes containing bacterial culture in BHI agar. Positive control was 0.2% chlorhexidine digluconate (CHX). RESULTS: After incubation, the adhesive components of CPB and CSEB, liquid A of XIII and C3SB did not present antibacterial activity when applied to paper discs. The non-light-activated CPB primer+adhesive promoted the greatest inhibition of Streptococcus mutans (p<0.05), whereas with light-activation, there was no significant difference between primer+adhesive and primer alone. For Lactobacillus acidophilus, CPB primer presented the greatest antibacterial activity in both light-activation conditions (p<0.05). Regarding the dentine discs, only CHX promoted an inhibitory effect, though less intense than on paper discs (p<0.05). CHX presented greater antibacterial activity against S. mutans than against L. acidophilus (p<0.05). CONCLUSIONS: Light-activation significantly reduced the antibacterial activity of the self-etching adhesive systems; MDPB incorporation contributed to the effect of adhesive systems against cariogenic bacteria; the components eluted from the adhesive systems were not capable to diffuse through 400 microm-thick dentine disc to exert their antibacterial activity against cariogenic bacteria.