Alterations in HbA1c following minimal or enhanced non-surgical, non-antibiotic treatment of gingivitis or mild periodontitis in type 2 diabetic patients: a pilot trial.

AIM: The purpose of this pilot study was to determine and compare the effects of two protocols aimed at reducing periodontal inflammation, upon the metabolic control of the diabetic condition in subjects with elevated baseline glycosylated hemoglobin (HbA1c). METHODS AND MATERIALS: Forty-two non-smoking type 2 diabetes subjects with mildly elevated HbA1c (>7 but < 9%) and severely elevated (>9%) were randomized to one of two non-surgical periodontal therapy protocols. Patients in the "minimal therapy" (MT) group received scaling, root planning, and oral hygiene instructions on two occasions six months apart. Participants randomized to the "frequent therapy" (FT) protocol received scaling, root planing, and oral hygiene instructions at two-month intervals and were provided a 0.12% chlorhexidine rinse for home use twice daily. Neither systemic nor local antibiotics were provided to either group. Subjects were asked to report any changes in diabetic medications, nutrition, and physical activity. Data analyses (ANOVA, t-test, Mann-Whitney) grouped subjects according to baseline HbA1c (>7 and < 9%, or > 9%), treatment protocol (minimal or frequent), and +/- medication change. RESULTS: In both MT and FT groups the clinical attachment level (CAL) remained unchanged but the other measures [gingival index (GI) and pocket dept (PD)] of periodontal health improved. Mean reductions in plaque showed improvement but calculus was worse in the FT group, likely due to the use of chlorhexidine. At six months, the largest reduction of HbA1c was 3.7; experienced by a subject receiving FT but no changes in diabetic medication. Among the MT and no medication change subjects, the maximum reduction was 1.6. Overall mean reduction in HbA1c of 27 subjects with baseline HbA1c >9.0 and no medication change was 0.6 with no statistical difference between the MT and FT groups. Among the medication-change subjects with baseline HbA1c >9.0, mean reduction of 1.38 was seen with FT compared to 1.10 with MT. CONCLUSION: Overall, modest improvements in HbA1c were detected with a trend towards FT being better than MT. Although this pilot trial was under-powered to detect small between-group differences, the magnitude of our findings (0.6 mean improvement in HbA1c) matches closely findings from the only meta-analysis conducted on this topic to date. Larger scale studies must be undertaken on diabetic patients with periodontal problems. CLINICAL SIGNIFICANCE: Preventive periodontal regimens for diabetic patients should be sufficiently intense and sustained to eliminate periodontal inflammation and should be closely coordinated with the patient's overall clinical diabetic management.

The influence of system compliance and sample geometry on composite polymerization shrinkage stress.

The objective of this study was to use finite-element analysis to model tensilometer tests of polymerizing dental composites. A typical sample in polymerization shrinkage stress tests is shaped like a flat disk, that is, has a high aspect ratio (ratio of diameter to height). In the experimental literature it is implied that the induced stress state in the flat disk composite samples is uniaxial. Three published tensilometer tests of curing dental composite samples with similar high aspect ratios (varying from 3 to 5) were modeled, but with test configurations having low, intermediate and high relative compliance (a tenfold variation). With the use of linear elastic finite element analysis, an instantaneous volumetric shrinkage of 1% was applied to the composite via the thermal analogy and the following questions were addressed: 1. Does the numerically predicted state of stress in composite samples tested in this fashion differ substantially from the uniaxial stress state assumed in the experiments?2. How do the numerically predicted stresses compare with the experimentally determined nominal stresses?3. Does compliance of the mountings influence the numerically predicted stress state? The finite-element results predicted a complex triaxial stress state that was strongly influenced by the compliance of the mountings. For the low and intermediate system compliance the model overpredicted the polymerization contraction stress, as would be anticipated due to the inability of the model to account for viscoplastic flow. For high system compliance, the numerical and experimental stress values were in better agreement, mainly because the linear elastic mountings accounted for most of the measured system compliance.