Bilateral variation of the masseteric myotatic reflex and the silent period in young humans

Increased bilateral differences in jaw reflexes have been considered as pathological findings. The aim of this study was to investigate the normal variation between sides in the jaw jerk and the silent period and determine the range of its boundaries, using the present experimental set-up. Electromyographic data were simultaneously recorded from the right and left masseter muscles by surface electrodes, using a computerized recording and analysis system. The reflexes were elicited by chin taps during mandibular rest and at moderate intercuspal clenching in 20 healthy dentate adults (10 males and 10 females) with a mean age of 26 years. The reflexes were always elicited bilaterally and no overall significant differences were observed between sides for occurrence, latency, duration and amplitude of the jaw jerk and for the latency and duration of the silent period (P > 0.05). However, in the individual analysis significant bilateral variation was occasionally recorded, particularly for the jaw jerk at rest and mainly in the amplitude measurements. On the other hand, in the silent period duration measurements individual variation was very limited. Bilateral individual latency differences for the jaw jerk did not exceed 1 ms at rest (x = 0.3 +/- 0.3 ms) and 0.7 ms at clench (x = 0.3 +/- 0.2 ms), while latency differences for the silent period did not exceed 0.8 ms for the early type (x = 0.4 +/- 0.2 ms) and 4.8 ms for the late phase of depression (x= 1.9 +/- 1.7 ms). Bilateral differences for the silent period duration did not exceed 7.1 ms (x = 2.2 +/- 2.3 ms) in the early type (simple + early phase of combined types) and 3.3 ms (x = 1.5 +/- 0.9 ms) in the total duration of the combined types.     

Effectiveness of gutta-percha removal with and without the microscope

The microscope may be useful in retreatment to enhance removal of gutta-percha (GP) and to identify deficiencies in the original treatment. This study compared the effectiveness of GP removal with and without a microscope. Forty-five extracted canines were stepback prepared and obturated with GP and Roth's sealer using lateral condensation. Teeth were stored for 17 months in a humidor, then divided into four groups: group 1 (n = 20)--GP removal without aid of the microscope (group 1 criteria for GP removal was lack of GP on final files and on paper points agitated within the chloroform-filled canal); group 2 (n = 20)--GP removal with the microscope. (In addition to group 1 criteria, canals were inspected with the microscope; additional GP was removed when identified. In both groups, GP was removed using a combination of mechanical instrumentation, chloroform solvent, and K-files); group 3 (n = 3)--positive control, canals remained obturated; and group 4 (n = 2)--negative control, canals were neither prepared nor obturated. Teeth were split longitudinally, photographed, then divided into thirds to compare the apical, middle, and cervical thirds. Remnants of GP and sealer on the canal wall were traced with a digitizer, and the remaining mean % GP was analyzed by t test. Group 1 had 8.3% remaining GP, and group 2 had 7.3% remaining GP. There was no significant difference demonstrated between the two experimental groups.     

Histologic observations of periodontal wound healing after treatment with PerioGlas in nonhuman primates

The effect of PerioGlas (synthetic bone particulate) on wound healing of experimental palatal periodontal defects in monkeys was evaluated. Chronic periodontal defects were created on the palatal aspects of maxillary molars and premolars. Open-flap debridement was performed. Experimental sites received PerioGlas, while control sites received no further treatment. Histologic measurements were performed on new bone, new cementum, epithelial downgrowth, and recession. Results showed significantly more new cementum and less epithelial downgrowth in the sites that received PerioGlas (P < 0.05). The present results indicate that PerioGlas may enhance periodontal wound healing outcomes.     

Microbial factors and gingival crevicular fluid aspartate aminotransferase levels

Abstract. The aim of this cross-sectional study was to investigate the clinical application of chairside tests for gingival crevicular fluid (GCF) aspartale amino-transferase (AST) levels and plaque BANA hydrolysis activity with the presence of the periodontal pathogens Porphyromonas gingivalis and Actinohacillus action-mycetemcomitans. The study comprised 100 periodontitis sites (pocket depths≥4 mm. GI = 3) from 10 patients with chronic adult periodontitis and 100 control sites (pocket depths <4 mm. GI<3) from 10 periodontally healthy patients comprising 55 healthy sites (pocket depths <4 mm. GI=0) and 45 gingivitis sites (pocket depths <4 mm, GI=1 or 2). The values for both BANA hydrolysis and AST levels were significantly higher in samples from periodontitis compared with gingivitis and healthy sites (p<0.001), A. actinomycetemcomitans was identified in 45% and P. gingivalis in 17% of periodontitis sites but neither pathogen was recovered from control sites and there was no significant correlation with (he clinical parameters measured. There was no significant relationship between the presence of P. gingivalis and/or A. actinmycetemcomitans with BANA hydrolysis or AST levels. A significant correlation (p=0.0017) was observed between BANA hydrolysis and pocket depth and between AST hydrolysis and the GI (p=0.01). This study failed to demonstrate a positive association between chairside analysis of GCF metabolites for AST levels and/or BANA hydrolysis with P. gingivalis and A. actinomycetemcomitans. However, the GCF metabolites had a significant correlation with periodontally diseased sites in patients with chronic adult periodontitis and may help confirm clinical observations.     

Extended bleaching of tetracycline-stained teeth: a 5-year study

Bleaching tetracycline-stained teeth is the most challenging form of tooth lightening. This article reports on 44 subjects who bleached their tetracycline-stained teeth for 6 months using trays with reservoirs overnight in a half-mouth designed study and 2 of 3 different concentrations of carbamide peroxide (10%, 15% or 20%). The subjects were followed for 5 years. The area evaluated was the middle third of the teeth. More than 55% of tooth lightening occurred within 1 month; after 5 years, more than 65% of the maximum tooth whitening remained for all 3 gel concentrations. Tooth whitening can be accomplished with any of the 3 concentrations used.     

Microhardness evaluation of in situ vital bleaching on human dental enamel using a novel study design.

OBJECTIVES: The aim of this 'in situ' study was to evaluate the microhardness of dental enamel following treatment with an in-office and an at-home vital bleaching agent through a novel approach using samples temporarily bonded 'in vivo'. METHODS: Human dental enamel slabs (n=88) were subjected to sequential polishing and initial Knoop microhardness tests were performed. The slabs were fixed to the facial surfaces of the maxillary first molars of 44 human volunteers. They were divided into four groups (n=11) according to the treatment group: G1- in-office-CP37+ at-home-CP10; G2- in-office-CP37+ at-home-PLA; G3- in-office-PLA and at-home-CP10; G4- in-office and at-home-PLA. After 3 weeks of treatment, final microhardness measurements were performed. RESULTS AND SIGNIFICANCE: ANOVA and Tukey's HSD hoc analysis (alpha=0.05) revealed no differences among initial or final microhardness values (p>0.05); however, significant differences occurred between initial and final values for each group (p<0.01), The evaluation of microhardness revealed a reduction of 6.8% for G1, 4.1% for G2, 3.4% for G3 and 3.5% for G4. In-office bleaching with 37% carbamide peroxide, an at-home bleaching with 10% carbamide peroxide, and a combination of both resulted in lower enamel microhardness when measured immediately post-treatment. However, long-term effects of these treatments are not known, and are believed to be clinically insignificant due to the relatively small reductions observed in enamel microhardness. Interestingly, the carrier, Cabopol 934P, also resulted in similar reduction in enamel microhardness even when administrated alone as a placebo.     

The effect of one session of supragingival plaque control on clinical and biochemical parameters of chronic periodontitis

Supragingival plaque control is a requisite for the success of any periodontal procedure. However, little is know about the effect of this procedure alone on periodontitis. The aim of this study was to determine the effect of supragingival plaque control on clinical and biochemical parameters of chronic periodontitis. Twenty-five subjects exhibiting at least 4 pockets > 5mm, non-smokers and with no relevant systemic diseases, were selected for the study. The clinical and biochemical assessments were done before and 21 days after removal of plaque retentive factors, extraction of affected teeth and instruction in oral hygiene. The statistical analysis was done with the Student paired t-test (p<0,05) and demonstrated a reduction on the percentage of sites with bleeding on probing from 42.72 ± 15.83 to 35.87 ± 13.30 (p=0.002). Reduction in probing depth was detected on anterior teeth (initial/final mean: 2.88 mm/2.78 mm; p=0.01) and interproximal sites (initial/final mean: 3.80 mm/3.65 mm; p=0.001). There was an increase from 66.81% to 68.65% in the number of sites with probing depth of 1 to 3mm and a decrease from 26.21% to 24.17% in those with probing depth of 4 to 6mm. The BAPNA results showed a decrease from 51.44 ± 20.78 to 38.64 ± 12.34 (p=0.04). This study demonstrated that supragingival plaque control provides a reduction in gingival inflammation and alterations in the subgingival microflora detected by the BAPNA test.     

Craniofacial morphology and inclination of the posterior slope of the articular eminence in female patients with and without condylar bone change

This study investigated the association of craniofacial and glenoid fossa shapes and temporomandibular joint (TMJ) pathology in 39 orthodontic patients with signs and symptoms of TMJ disorders, using helical CT scans. Cephalometric measurements showed that 21 subjects with bilateral condylar bone change (BBC) had significantly smaller SNB angles, ramus heights and S-Ar/N-Ba ratios, as well as larger mandibular plane angles and lower anterior facial height than the 18 subjects with no condylar bone change (NBC). The average posterior slope of the left and right articular eminence in their central and lateral sections was significantly steeper in NBC than in BBC. Condylar bone change might, therefore, not only be related to the morphology of the mandible, but also of the glenoid fossa and cranial base. This appears to reflect adaptive changes in the condyle, articular eminence and cranial base in response to changes in loading.     

Locally produced anti-phosphorylcholine and anti-oxidized low-density lipoprotein antibodies in gingival crevicular fluid from aggressive periodontitis patients

BACKGROUND: Sera from patients with periodontal attachment loss contain higher concentrations of IgG anti-phosphorylcholine (anti-PC) than sera from healthy subjects. Furthermore, a large proportion of plaque bacteria bear PC-containing surface antigens, implicating the oral flora as a source of immunogen for anti-PC. Additionally, anti-PC is cross-reactive with a variety of oral bacterial antigens and human antigens such as oxidized low-density lipoprotein (oxLDL). We hypothesized that, if the oral flora is a source of PC antigens, then we should be able to detect local anti-PC and anti-oxLDL production in gingival crevicular fluid (GCF). METHODS: To test this, we collected 66 GCF samples from 15 patients with aggressive periodontitis and examined both the GCF samples and serum samples for their content of IgG anti-PC, IgG anti-LDL, and IgG anti-oxLDL by enzyme-linked immunosorbent assay. We also determined levels of anti-tetanus toxoid (anti-TT) as a non-oral antigen control. Serum and GCF concentrations of serum albumin (HSA) were also determined for use as a dilution marker. A conservative GCF:serum antibody ratio of greater than 1.5 was considered to be evidence of local antibody production. RESULTS: For the non-oral antigen TT, only one out of 62 samples contained locally produced antibody. Eight out of 64 samples (7 from a single subject) demonstrated local production of anti-LDL. In contrast, 28 out of 66 samples demonstrated local production of anti-PC, and 47 out of 66 samples contained locally produced anti-oxLDL. It was observed that A. actinomycetemcomitans strains containing or devoid of PC could absorb anti-oxLDL from human sera. Although there was a correlation between the ratios of anti-PC and anti-oxLDL (Spearman's rho = 0.35, P = 0.0037), local production of both antibodies was found in only 17 out of 65 samples, indicating that these antibodies are not always reflective of reactivity to the same antigens. CONCLUSION: The local production of anti-PC and anti-oxLDL further implicates the oral flora as a source of antigen that may mediate immune reactions of relevance to cardiovascular and other systemic diseases.     

Human periodontal ligament cell responses to recombinant human bone morphogenetic protein-2 with and without bone allografts

BACKGROUND: Recombinant human bone morphogenetic protein-2 (rhBMP-2) has been found to promote the osteoblastic differentiation of human periodontal ligament cells. Its effect depends on the delivery system used. In this study we examined the effect of rhBMP-2 on the proliferation and osteoblastic differentiation of human periodontal ligament cells cultured alone or with 3 different bone allografts. METHODS: The rhBMP-2 effect on cell proliferation and osteoblastic differentiation was examined by measuring [3H] thymidine incorporation and ALPase activity, respectively, on human periodontal ligament (hPDL) cells. Two human demineralized freeze-dried allografts of cortical (DFDBAco) and cancellous (DFBDAca) bone origin and 1 non-demineralized freeze-dried allograft (FDBA) of cancellous bone origin, derived from different tissue banks, were used to evaluate the rhBMP-2 effect on cell osteoblastic differentiation. The measurements were taken on various days. RESULTS: rhBMP-2 decreased hPDL cell proliferation. rhBMP-2 acted on the third day of the process of cell differentiation, had a specific time of action, achieved its peak effect on the fourth and fifth days, and then did not provoke any further effects. The 3 bone allografts were efficiently combined with rhBMP-2. The combination of rhBMP-2 and DFDBAco showed the effect with the longest duration. rhBMP-2, on day 4, made the inactive bone allograft more active while, on the other days, its effect was dependent on the allograft alone. CONCLUSIONS: rhBMP-2 promotes the osteoblastic differentiation of human periodontal ligament cells and decreases cell proliferation. In this study rhBMP-2 in the presence of the bone allografts tested resulted in hPDL cell differentiation.