Comparison of hand-traced and computer-based cephalometric superimpositions.

OBJECTIVE: To determine the ability to produce comparable superimpositions using hand tracing and digital methods (Dolphin v10). In addition, if the two methods were comparable, we wanted to determine if a difference existed between the best-fit cranial base superimposition and S-N superimpositions using the digital method. METHODS AND MATERIALS: Sixty-four initial (T(1)) and final (T(2)) cephalometric film radiographs were obtained. Cranial base and regional superimpositions were completed independently for each pair of radiographs by either hand tracing and digital methods. To quantitatively evaluate the differences between the two methods, the hand and digital superimpositions were digitized to obtain x-y coordinates of routine cephalometric landmarks at T(2). Linear distance between multiple corresponding (hand and digital) T(2) cephalometric landmark locations (e.g., A point) were measured and defined as the T(2) landmark distance (T(2) LD). Additionally, 61 patient records were used to compare the digital method for best-fit cranial base superimpositions versus S-N superimpositions. A Friedman test was applied to examine for differences. RESULTS: The upper 95% confidence limit for the mean of the T(2) LD for hand and digital superimposition methods was <1 mm for all landmarks except maxillary incisor tip and apex. The upper 95% confidence interval for best-fit vs S-N was >1 mm for most landmarks. CONCLUSION: This study validates the use of superimpositions produced by Dolphin Imaging version 10 and is a necessary step forward toward widespread acceptance of digital superimpositions.

Biomechanical and histomorphometric analyses of monocortical screws at placement and 6 weeks postinsertion.

Maxillofacial screws are increasingly being used in orthodontics to provide anchorage for tooth movement. The objective of this study was to determine the biomechanical stability as well as the bone tissue response of screws at 6 weeks postinsertion in a canine model. Seven skeletally mature male dogs received 102 screws (2 x 6 mm or 2 x 8 mm) at predetermined sites. Twenty screws became loose or were lost during the 6-week undisturbed healing period. Forty-eight screws were randomized for mechanical testing and 34 for histology. Peak pullout strength was recorded and approximately 80-microm sections were examined for histomorphometric parameters. Statistical analyses were conducted by analysis of variance and Tukey-Kramer method. Mean +/- SE peak pullout strengths for the various sites ranged from 153.5 +/- 37.6 N to 389.3 +/- 32.5 N with no significant (P < .05) differences at immediate placement and 6 weeks postinsertion. Bone contact ranged from 79% to 95%. Histomorphometric analyses indicated higher bone formation rate in the mandible than in the maxilla and a gradient of decreasing turnover with increasing distance from the screw interface. These results provide the clinical orthodontist with an estimate of the holding power of these screws and an understanding of early biological healing response associated with self-drilling screws.

Stress-induced glucocorticoid response modulates mononuclear cell trafficking during an experimental influenza viral infection.

The migration, distribution, and localization of lymphoid cells throughout the body is critical to the efficiency and development of the immune response. This study examined the role of endogenous glucocorticoids in mononuclear cell (MNC) trafficking during the development of an immune response to infection by influenza A/PR8 virus. Accumulation of MNC in the draining lymph nodes and at the site of virus replication (lungs) was studied in infected mice, and infected mice subjected to a stressor (physical restraint). The glucocorticoid antagonist, RU486, was used to block the activity of endogenous corticosterone during development of the immune response. PR8-infected mice demonstrated an elevation in circulating corticosterone regardless of whether they were treated with RU486 or a placebo. Thus, some 'afferent' signal associated with the infection, and/or the immune response to infection, activated the hypothalamic-pituitary-adrenal axis (HPA) and was not subject to negative feedback regulation. The initial accumulation of MNC in the draining lymph nodes and lungs during infection, however, was independent of the glucocorticoid response. Our previous studies demonstrated that virally infected animals subjected to physical restraint had highly elevated plasma corticosterone levels, suppressed lymphadenopathy, and reduced accumulation of MNC in the lungs. In the present study, RU486 treatment restored cellularity to the draining lymph nodes and enhanced accumulation of MNC in lungs of stressed, A/PR8 virus-infected mice.

Kinetics of glucocorticoid response to restraint stress and/or experimental influenza viral infection in two inbred strains of mice.

The murine model of influenza viral infection was used to evaluate the effects of restraint stress on pathogenesis and survival in inbred strains of mice. We recently reported that restraint stress was associated with an enhanced probability of survival in one strain of inbred mouse, DBA/2, and not in another, C57BL/6. Those studies suggested that the protective mechanism(s) of stress on mortality in the DBA/2 mice might be attributable to elevated levels of circulating glucocorticoids. Therefore, daily levels of plasma glucocorticoids were measured during influenza viral infection in both these strains. The present studies demonstrated that influenza infection itself is perceived as a stressor in both C57BL/6 and DBA/2 mice as evidenced by elevated plasma glucocorticoid levels within 48 h of infection. However, augmentation of glucocorticoid levels was not seen in the DBA/2 mice that were also subjected to restraint stress during the course of infection. Thus, corticosterone levels alone did not account for the enhanced survival seen in this group of animals.

Stress-induced changes attributable to the sympathetic nervous system during experimental influenza viral infection in DBA/2 inbred mouse strain.

The murine model of influenza viral infection was used to evaluate the effects of restraint stress on pathogenesis and survival in the DBA/2 inbred strain of mice. Restraint stress has been associated with an enhanced probability of survival during influenza infection in this strain of mouse. Previous studies suggested that the protective mechanism(s) of stress on mortality might be attributable to elevated levels of circulating glucocorticoids. Subsequent work demonstrated that corticosterone levels alone could not account for the enhanced survival seen in the DBA/2 mice. The present studies examined the role of catecholamines in behavioral stress during influenza infection. It appears that glucocorticoids may play a primary role in trafficking and restriction of inflammation, while catecholamines may play role in limiting activation of virus-specific effector cells. The studies presented here suggest that the interplay between these two physiological response mechanisms needs to be coordinated to optimize development of the immune response to an infection.

Restraint stress differentially affects the pathogenesis of an experimental influenza viral infection in three inbred strains of mice.

Genetic variation in the response to stress may play a critical role in susceptibility to inflammatory diseases and development of the immune response. Experimental influenza viral infection was used to study the effects of restraint stress (RST) on pathogenesis and development of the immune response. Three inbred strains of mice (C57BL/6, DBA/2, and C3H/HeN) were infected with influenza A/PR8 and subjected to repetitive cycles of RST during development of the immune response. RST diminished cellular immune and inflammatory responses in all three strains; yet only the DBA/2 strain demonstrated RST-associated reduction in influenza viral-induced mortality.

Blood pressure and heart rate responses to anticipated high-stress dental treatment.

Twenty-four healthy adults participated in a study to determine the effects of anticipated high-stress dental treatment on blood pressure and heart rate. Blood pressure, heart rate, and state anxiety were assessed prior to four consecutive dental appointments. Appointments 1, 2, and 4 were of relatively low stress and appointment 3 was of relatively high stress. Blood pressure was unaffected while heart rate was highest prior to appointment 3 and lowest prior to appointment 1.

Inhibition of root surface caries in rice rats: use of a sodium fluoride dentifrice.

A sodium fluoride-containing dentifrice (Gleem) was evaluated for its efficacy to inhibit root surface caries in the rice rat. The dentifrice was diluted 50/50 with water so that the slurry contained 500 ppm fluoride. This slurry, a solution of 5000 ppm fluoride, and demineralized water were applied to the molar teeth twice daily for 10 weeks. Another group of rats was given 50 ppm fluoride in the drinking water. There was significantly less root surface caries in all groups of rats which received fluoride than in the demineralized water control animals. However, none of the fluoride preparations inhibited the loss of alveolar bone.

Effect of anti-oxidants on growth and lactic acid production by Streptococcus mutans.

The effects of three anti-oxidants--tertiary butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT)--on both growth and lactic acid production by eight cariogenic strains of Streptococcus mutans were investigated. Synergistic inhibitory effects of potassium sorbate on lactic acid production were also determined. All three anti-oxidants are phenolic derivatives and are commonly used in food systems due to their excellent "carry-through" properties during processing. Growth inhibition was determined by turbidity measurements at 600 nm. Lactic acid was assayed by gas chromatography, and bacterial DNA was assayed by the diphenylamine reaction. There were reduced growth levels of S. mutans due to the anti-oxidants and potassium sorbate for at least 12 hr, with TBHQ and BHA still inhibiting growth at 24 hr. Nearly all concentrations of anti-oxidants and potassium sorbate reduced lactic acid production by S. mutans, but only TBHQ significantly inhibited lactic acid production when the amount of acid per microgram DNA was calculated. A synergistic reduction of lactic acid production by S. mutans does occur in most combinations of potassium sorbate with anti-oxidants.

Anticariogenic effects of tea in rats.

Teas varying in fluoride and tannin concentration were evaluated in rats for anticariogenic activity. There was a direct correlation between fluoride in tea and the inhibition of sulcal caries in rats, whereas no relationship was observed between tannin and this type of lesion. Teas also had a significant effect on caries progression and imparted a black stain to the teeth.

Effect of antimicrobial agents on root surface caries, alveolar bone loss, and microflora in rice rats.

Two antimicrobial agents, 9-aminoacridine (0.2%) and minocycline (0.2%), were evaluated for their efficacy in inhibiting root surface caries, bone loss, and microflora in rice rats. A solution of 5000 ppm fluoride was used as a positive control for the inhibition of root surface caries, and double-distilled water was used as a negative control group. Each rat was treated by having its molar teeth swabbed 2 X per day with the prescribed agent in its group for nine weeks. Root caries reduction in the minocycline and fluoride groups was not significantly different, but the reduction was significantly greater than in the 9-aminoacridine group, with the caries score in all three groups being significantly less than that in the water control. Bone loss reduction for the minocycline group was significantly greater than that for any other group.

Effect of cheese, with and without sucrose, on dental caries and recovery of Streptococcus mutans in rats.

The objective of this study was to determine the effect of aged and young cheddar cheese with and without added sucrose on dental caries and the associated recovery of implanted Streptococcus mutans. Very little caries was observed in rats consuming cheese without sucrose. There was an increase in caries in rats fed cheeses with 20% sucrose, but this increase was not significant. There was significantly greater caries activity in rats fed standard diets containing 20% or 5% sucrose (SLS or MIT 305) than in rats fed cheeses containing 20% sucrose. Rats fed cheese or powdered diets containing sucrose had significantly higher frequency of recovery and higher levels of S. mutans infection than did rats fed cheese containing no sucrose. This study confirms the low cariogenic potential and possible cariostatic activity of cheddar cheese in rats. Since cheddar cheese with sucrose did not significantly interfere with S. mutans implantation, the cariostatic mechanism is apparently unrelated to a direct antimicrobial effect on S. mutans.

Plaque score changes based primarily on patient performance at specific time intervals.

Patient plaque removal is a major component of periodontal therapy and should be continuously monitored during and following treatment. There do not appear to be studies which address plaque score changes achieved primarily by patient performance from the time of initial presentation to, during, and following active therapy. We assessed individual tooth surfaces and segment plaque scores for 24 adult subjects presenting with periodontitis, the majority of which was ADA case types III and IV, at 3 time points (initial presentation, post-initial preparation, and at 3 months following active therapy), using the O'Leary Plaque Index. The assessments describing surfaces and segments were made prior to any professional intervention. Analysis of buccal (B), interproximal (I), and lingual (L) plaque retentive surfaces at t-0 indicated the mean plaque index on B and L surfaces (30.7% and 41.9% respectively) was less than that on I surfaces (79.6%). At t-1 and t-2, the mean plaque index on all three surfaces was significantly (P less than 0.05) less than at t-0. Analysis of plaque indices in each of 6 segments at each time point revealed that plaque scores in all segments, except the mandibular right segment, were analogously reduced from t-0 to t-1 and to t-2. Our results indicate that plaque reduction for all subjects based primarily on patient performance consistently approaches or exceeds 50% on all surfaces and that interproximal surfaces present with and retain more plaque than buccal and lingual surfaces. Furthermore, patient plaque performance achieved at the time of post-initial preparation may be a predictor of the plaque control achievable during therapy based on patient performance.

Retained "hopeless" teeth. Effects on the proximal periodontium of adjacent teeth.

The retention of teeth diagnosed as periodontally "hopeless" may accelerate the destruction of the adjacent proximal periodontium. Studies determining the influence these teeth have on the health status of adjacent teeth appear nonexistent. It was the intent of this retrospective study to assess the status of the periodontium in adjacent teeth proximal to the periodontium of "hopeless" teeth. We evaluated 17 teeth, each being mesially adjacent to one "hopeless" tooth, in 17 subjects treated for periodontal disease. In each case, the "hopeless" and the adjacent teeth received the same treatment. Probing depths (P-D), radiographic alveolar bone level (R-BL) and the width of the periodontal ligament space (W-PL) were measured for both the adjacent interproximal and the nonadjacent interproximal surface for each hopeless tooth. At both pretherapy and posttherapy, there were no significant differences for any of the variables (P-D, R-BL and W-PL) for the adjacent interproximal surfaces with the nonadjacent interproximal surfaces. However, there was a significant reduction in the mean probing depth for the adjacent interproximal surfaces, pretherapy to posttherapy. No other significant changes were found in any of the other variables for either the adjacent or nonadjacent interproximal surfaces. These data suggest that teeth considered periodontally "hopeless" and retained have no effect on the proximal periodontium of adjacent teeth prior to and following therapy.

The relationship of gingival fluid leukocyte elastase activity to gingival fluid flow rate.

Recent studies have suggested that leukocyte elastase activity (EA) in tissue exudates is an indicator of inflammatory disease. We assayed gingival fluid (GF) EA with a selective peptide substrate and compared it to GF flow rate with regard to its ability to detect differences in the clinical status of existing inflammatory periodontal disease in 56 human subjects. Compared to healthy sites (Gingival Index = 0, 1 to 3 mm) and mild gingivitis sites (GI = 1, 2 to 5 mm), mean GF EA was significantly (P < 0.05) higher at periodontitis sites with deep probing depths (GI = 2, 6 to 9 mm depth), but not at periodontitis sites with intermediate probing depths (GI = 2, 4 to 5 mm). When expressed as specific EA (i.e., normalized to GF protein content), mean EA was also significantly higher at deep periodontitis sites compared to healthy sites and mild gingivitis sites. In addition, specific EA was significantly higher at periodontitis sites with intermediate probing depths than at healthy sites. As predicted by previous studies, these significant increases in specific EA were associated with significant increases in mean GF flow rate. In contrast to specific EA, however, mean GF flow rate was significantly higher at gingivitis sites than at healthy sites. A strong correlation was observed between GF flow rate and specific EA (rs = 0.737, P = 0.0006). Thus, GF flow rate and GF EA appear to be related indicators of inflammation, but GF flow rate may be more sensitive to early inflammatory changes leading to mild gingivitis.

Gingival fluid ciprofloxacin levels at healthy and inflamed human periodontal sites.

BACKGROUND: Polymorphonuclear leukocytes (PMNs) take up and accumulate ciprofloxacin. This may allow them to enhance the delivery of this agent to the inflamed periodontium. METHODS: Cross-sectional and longitudinal approaches were used to test the hypothesis. In the cross-sectional study, 7 periodontally healthy adults and 8 adults with untreated periodontitis were administered three doses of ciprofloxacin (500 mg bid). Gingival fluid (GF) and serum samples were obtained after 28 hours and analyzed by high-performance liquid chromatography (HPLC). In the longitudinal study, 8 adult periodontitis subjects were administered 500 mg ciprofloxacin bid for 8 days. After 28 hours, GF from 4 sites with 5 to 8 mm probing depths was sampled in each subject, serum samples were obtained, and 2 of the 4 sites were root planed. GF and serum were sampled again 7 days later (196 hours after the initial dose). RESULTS: The mean ciprofloxacin levels in the GF and serum of periodontally healthy subjects were 2.52 +/- 0.22 microg/ml and 0.47 +/- 0.05 microg/ml, respectively. In subjects with periodontitis, these levels were 2.69 +/- 0.44 microg/ml and 0.61 +/- 0.13 microg/ml, respectively. GF ciprofloxacin levels were significantly higher than corresponding serum levels in healthy and diseased subjects (P<0.01), but there were no significant differences in GF or serum levels between the 2 subject groups. Since GF flow was significantly higher at diseased sites, however, more ciprofloxacin was distributed to these sites than to healthy sites. In the longitudinal study, GF flow at 196 hours was 16% lower at root planed sites than at untreated control sites (P = 0.412). The minor decrease in this index of inflammation was accompanied by a small (9%), but statistically significant (P= 0.007), decrease in GF ciprofloxacin levels. CONCLUSIONS: GF ciprofloxacin levels decreased slightly at inflamed periodontal sites after root planing, but were significantly higher than serum levels even at healthy periodontal sites. Inflammation may enhance the distribution of ciprofloxacin to diseased sites, but it is not a major determinant of GF ciprofloxacin levels.

The effectiveness of a disposable tooth cleansing device on plaque.

A disposable polyester foam sponge on a stick, impregnated with a non-foaming dentifrice, has been widely dispensed to hospitalized and nursing home patients for intraoral cleansing and refreshing. Since no information was found relative to tooth cleansing capabilities, we have evaluated its effectiveness in the removal of accumulated plaque and also in prevention of plaque accumulation. Removal of 72 hours of accumulated plaque was assessed in a cross-over design study comparing the device with a commercially-available toothbrush by two different groups of 13 and 29 adult, healthy subjects who used each instrument for 1 and 3 minutes respectively. No significant differences were found between mean scores assessed by Turesky's modification of the Quigley-Hein plaque index by either group using either instrument at either time period (P > 0.05). Prevention of plaque accumulation was assessed in a third group of 25 subjects who used each instrument an average of 3 times a day for 1 week in a cross-over study. While the toothbrush was found significantly more effective in retarding the accumulation of plaque from a plaque-free baseline on both facial and lingual surfaces (P < 0.02), the tooth cleansing device still retained plaque-preventive capabilities by maintaining plaque formation below 2 mm at the cervical margin of the tooth. Results of this study indicate the tooth cleansing device may be a viable alternative to conventional toothbrushes.

Clinical comparison of bioabsorbable barriers with non-resorbable barriers in guided tissue regeneration in the treatment of human intrabony defects.

The purpose of the study was to compare the effects of guided tissue regeneration (GTR) with expanded polytetrafluoroethylene (ePTFE) non-resorbable barriers and polylactic acid bioabsorbable barriers in humans with intrabony defects due to periodontitis. Ten patients presented with 2 intrabony defects each. Mucoperiosteal flaps were performed. One of the defects was randomly assigned for placement of the ePTFE barrier over the roots and alveolar bone and the other defect with placement of the polylactic acid barrier. A minimum of 9 months after barrier placement, surgical reentry was performed. The data were evaluated by the Wilcoxon matched-pairs signed-ranks test and the Fisher exact test. Treatment with both types of barriers produced significant changes from baseline for all parameters, except in the ePTFE group for the amount of bony crest resorption (P = 0.055) and in the polylactic acid group for increased recession (P = 0.109). The results showed no significant differences between the barriers for any parameters: probing depth reduction (polylactic acid 2.60 +/- 1.90, ePTFE 2.80 +/- 1.40; P = 1.000); attachment gain (polylactic acid 1.40 +/- 1.43, ePTFE 1.90 +/- 1.29; P = 0.336); increased recession (polylactic acid 0.80 +/- 1.40, ePTFE 1.10 +/- 0.99; P = 0.531); amount of vertical bone fill (polylactic acid 1.60 +/- 1.84, ePTFE 2.00 +/- 2.49; P = 0.984); bony crest resorption (polylactic acid -1.30 +/- 1.06, ePTFE -1.30 +/- 1.63; P = 1.000); depth of bony defect reduction (polylactic acid 2.90 +/- 1.20, ePTFE 3.30 +/- 1.70; P = 0.750); width of bony defect reduction (polylactic acid 2.20 +/- 1.23, ePTFE 2.20 +/- 1.23; P = 0.875); or volumetric changes (polylactic acid 33.50 +/- 19.70 microl, ePTFE 34.00 +/- 18.40 microl; P = 0.750).

Testing reliability of plaque and gingival indices. Two methods.

This investigation was undertaken to compare two methods of interexaminer and intraexaminer reliability in the evaluation of Plaque and Gingival Indices prior to a study of toothbrushing. Inter-/intraexaminer reliabilities were compared using a projected slide series consisting of 40 slides of clinical examples of gingival inflammation and plaque accumulation. Time between assessments was three weeks. Using the slide technique, intraexaminer reliability was established for: (1) Gingival Indices and (2) Plaque Indices. Interexaminer reliability was also established for Gingival Indices. Interexaminer reliability could not be established for Plaque Indices on the first assessment but was established on the post-assessment. Intraexaminer reliability was also determined through clinical examinations of patients. A third clinician was used to manipulate the tissue while investigators evaluated bleeding on provocation and plaque accumulation. Significant results were established for the Gingival Indices and Plaque Indices. Results of this investigation suggest that significant inter-/intraexaminer reliabilities may be obtained for gingival indices using the slide technique. In addition, the clinic technique appeared useful for assessing interexaminer reliability for Gingival Indices. Plaque Indices using the slide technique required more practice than those using the clinic technique.

Retained "hopeless" teeth: lack of effect periodontally-treated teeth have on the proximal periodontium of adjacent teeth 8-years later.

We previously reported the lack of effect periodontally-treated teeth prognosed "hopeless" and retained for 3.4 +/- 1.5 years have on the proximal periodontium of adjacent teeth. We now report our findings for the same group of subjects following 8.4 +/- 0.7 years of "hopeless" tooth retention. Of the 17 "hopeless" and adjacent teeth originally measured in 17 subjects, 14 of the subjects were still available for re-evaluation. Measures used to assess the periodontium of proximal surfaces of adjacent teeth included pocket depths (PD), radiographic alveolar bone level (R-BL), and periodontal ligament space width (W-PL). Treatment for the subjects consisted of surgical therapy (N = 15) and scaling and root planing (N = 2). Of the 14 subjects re-examined, 2 were eliminated due to loss of adjacent tooth reference points and 2 due to extraction of the "hopeless" tooth (N = 10). Differences in measurements (i.e., nonadjacent to "hopeless" tooth value minus adjacent to "hopeless" tooth value) were analyzed using a repeated measures ANOVA. There were no significant differences for PD (P = 0.20), R-BL (P = 0.29), or W-PL (P = 0.16). These data confirm our original findings that retained periodontally "hopeless" teeth do not significantly affect the proximal periodontium of adjacent teeth following therapy.