Levels of mutans streptococci and lactobacilli in plaque on aged restorations of an ion-releasing and a universal hybrid composite resin

The purpose of this in vivo study was to evaluate the cariogenic microflora of plaque on aged restorations of a hydroxyl, fluoride, and calcium ion-releasing composite resin (IRCR) (Ariston pHc), and to compare it intra-individually with a universal hybrid composite resin and enamel. Each of 19 subjects received one proximal restoration of the IRCR, one proximal universal hybrid composite resin restoration (CR) and each subject had one non-filled proximal enamel control surface to make intra-individual comparisons possible. To avoid peak ion releases from the materials, aged restorations were studied. Plaque was collected from 57 surfaces using sterile applicator tips. Samples were cultured to determine the numbers of mutans streptococci, lactobacilli, and total microorganisms. The relative numbers for mutans streptococci (% of total bacteria) were: IRCR 0.59%, CR 0.40%, enamel 0.22%. Two outliers were found in the IRCR group. Excluding these outliers resulted in a relative number of 0.33%. Lactobacilli were detected in the plaque from only 9 surfaces and at very low relative proportions for all three surfaces: 0.01%. The enamel surfaces showed the lowest relative numbers of mutans streptococci and lactobacilli, but the differences were not significant. It can be concluded that the ion release of the IRCR did not influence the growth of cariogenic microorganisms in dental plaque.     

Influence of experimental neutropenia in dogs with chronic gingivitis

The influence of a four day period of experimental neutropenia on the clinical state and the structural constituents of chronically inflamed gingiva has been studied in four beagle dogs. Neutropenia was induced by heterologous anti-neutrophil serum. The effects on the gingiva were evaluated by Gingival Index (GI) and Gingival Exudate measurements and by morphometric analysis of various tissue components in sections from biopsies of buccal gingiva sampled on days 2, 3, and 4. Control biopsies were obtained before induction of neutropenia. The GI did not markedly change during the observation period. The amount of Gingival Exudate, however, significantly decreased following the induction of neutropenia and remained low throughout the experiment. Neutrophilic granulocytes disappeared in the gingival tissues, while, apart from a relative increase in plasma cells, no other tissue components seemed to change. No bacterial invasion of the junctional epithelium or of the gingival connective tissue could be observed. Thus during a four day period the bacterial defense mechanisms at the dentogingival junction seem to be able to prevent penetration of microorganisms into the gingival tissues despite the absence of neutrophilic granulocytes.     

Specific IgA subclass responses in serum and saliva: a 12-month follow-up study after parenteral booster immunization with tetanus toxoid

Specific IgA subclass antibodies against tetanus toxoid in serum, parotid saliva, and whole saliva were quantified after booster immunization. Samples from 14 healthy individuals were collected before and 1, 6, and 12 months after subcutaneous injection with Duplex (0.23 ml tetanus toxoid 30 Lf/mL and diphtheria 7.3 Lf/mL). Samples of whole saliva were also collected after 2 weeks. Specific IgA1 and IgA2 subclass antibodies to tetanus toxoid were quantified by enzyme-linked immunosorbent assay (ELISA). In this quantitative method, chimeric IgA1 and IgA2 antibodies directed against NP (4-hydroxy-3-nitrophenacetyl) were used as standards. Total levels of IgA1 and IgA2 were measured using a nephalometer or ELISA. Immunization with tetanus toxoid resulted in raised mean values of specific IgA1 and IgA2 antibodies against tetanus toxoid in serum after 1 month. Compared with the baseline, the mean value of specific IgA1 antibodies showed a 2.6-fold increase (mean value 10.47 microgram/mL) in serum, and that of specific IgA2 antibodies a 2.7-fold increase (mean value 0.93 microgram/mL). Specific IgA subclass antibody levels in parotid and whole saliva were unchanged after 1 month. The ratio of specific IgA subclass antibodies to total IgA subclass antibodies was 3 to 10 times higher in parotid saliva compared with whole saliva. In conclusion, subcutaneous booster immunization with tetanus toxoid induced immune responses of both antigen-specific IgA1 and IgA2 subclass antibodies in serum with the same increase, whereas the levels of specific IgA subclass antibodies in secretory fluids were unchanged. The ratio of specific IgA subclass antibodies to immunoglobulins was higher in parotid saliva compared with whole saliva.     

Mercury inductions in persons with subjective symptoms alleged to dental amalgam fillings

This study was carried out to determine whether health disturbances alleged to mercury release from dental amalgam fillings, i.e. "amalgam disease", may be caused by an increased sensitivity to mercury (Hg). In the form of a double-blind test, 39 volunteers who themselves suspected "amalgam disease" inhaled small doses of mercury vapour (0.6-10 microg) or pure air in a random sequence. After the induction procedure, the test persons assessed whether they reacted or not, i.e. experienced increased illness or not. The test persons also registered the daily intensity of their various symptoms. Calculated on the whole population, there was no statistically significant difference between the number of reactions after inhalation of mercury vapour compared with after inhalation of air. Two subjects, however, reacted significantly more often to mercury vapour than to air. The results do not support that short-term exposure to low doses of Hg vapour in general promotes clinical illness in subjects who themselves suspect "amalgam disease". The deviating reactions presented by two test persons, however, may support the theory that occasional individuals can be sensitive to very low doses of Hg.     

The influence of a 0.2% chlorhexidine mouthrinse on plaque regrowth in orthodontic patients

In a prospective plaque regrowth study focusing on oral hygiene during fixed appliance therapy 12 adolescent patients (mean age 14.1 +/- 1.5 years) were evaluated twice over 2-day test periods. In the randomized, double-blind study the influence of a 0.2% chlorhexidine (CHX) mouthrinse (Corsodyl) and a commercially available dentifrice supplementing fluoride (Odol-med-3) were compared intra- and interindividually in a crossover design with regard to plaque and gingivitis. Before starting the first test phase there was a 14-day preliminary phase for upgrading the oral hygiene. Between the 2 test phases was a 5-day "washout". On the last day of the second test phase the patients were asked to fill in a questionnaire concerning their experiences during the study. The 0.2% Corsodyl reduced the plaque index scores significantly (p < 0.001). The gingival index revealed a similar reduction (2nd day of test: p = 0.03). Until the 5th day of washout a clear-cut carryover effect of the chlorhexidine rinse on the gingival index was observed. Both the lower mean values of the 2 clinical parameters at the beginning of the test phases as compared with those at the beginning of the preliminary phase and the evaluation of the questionnaires indicated a possible Hawthorne effect. 0.2% Corsodyl may be employed as an adjunct to other preventive measures such as professional care and patient-oriented instruction on an intermittent basis in order to reduce the plaque-induced iatrogenic side effects and to enhance the efficacy of oral hygiene measures in connection with orthodontic therapy with fixed appliances.     

Influence of Masticatory Muscle Function on Transverse Skull Dimensions in the Growing Rat

AIM: The aim of this study was to elucidate the influence of reduced masticatory muscle function on the transversal dimensions of the premaxilla, maxilla (including the dental arch) and the calvaria in the growing rat. MATERIAL AND METHODS: 38 growing male albino rats were used. 14 animals were killed at the beginning of the experiment to provide baseline values (Young Group). The remaining animals were randomly divided into two equal groups; one received the ordinary diet in hard pellet form (Hard Diet Group), and the other a soft diet (Soft Diet Group). The experimental period started when the rats were 28 days old and had a duration of 28 days. 3D measurements of the dentofacial skeleton were performed on dry skulls with a Reflex microscope. RESULTS: No inter-group differences were found in mean body weight and overall length of the cranium. The dental arch was found to be narrower in the third molar region in the Soft Diet Group, possibly due to less growth in the midpalatal suture and/or to reduced occlusal loading. This may be due to the first and second molars having been in occlusion at the beginning of the experimental period, while the third molars were not. Furthermore, the premaxilla and the frontal bones at the most lateral part of the temporal crest were narrower in the Soft Diet Group, these regions being areas of masticatory muscle attachment.     

Evaluation of accuracy of computer-aided intraoperative positioning of endosseous oral implants in the edentulous mandible

The overall accuracy of a novel surgical computer-aided navigation system for placement of endosseous implants was evaluated. Five dry cadaver mandibles were scanned using high resolution computed tomography (HRCT). The position of four interforaminal dental implants was planned on the computer screen and transferred to the cadaver mandibles using VISIT, a surgical navigation software developed at the Vienna General Hospital. The specimens were HRCT-scanned again to compare the position of the implants with the preoperative plan on reformatted slices after matching of the pre- and postoperative data sets using the mutual information technique. The overall accuracy was 0.96 +/- 0.72 mm (range 0.0-3.5 mm). No perforation of the mandibular cortex or damage to the mandibular canal occurred. We conclude that computer-aided implant surgery can reach a level of accuracy where further clinical developments are feasible.     

Experimental contact hypersensitivity in the gingiva of dogs

Application of l-dinitro-2.4-chlorbenzene (DNCB, 0.05 % in Orabase^®) onto the gingiva in one side of the jaws was performed daily for six days in a group of sensitized dogs. Contralaterally only the vehicle was applied. Anti-thymocyte serum (ATS) was injected into the dogs after three days of application. The effects on the gingiva were studied by inflammatory cell counts in sections of gingival biopsies and by measurements of crevicular leukocytes, gingival fluid and acid phosphatase activity in crevicular samples.
The numbers of inflammatory cells in the gingival biopsies as well as the figures of the gingival crevice parameters were higher in the DNCB side as compared to the control side on day 3. Immuno-suppression with ATS affected all parameters as observed from the data of day 6 of the experiment. The results of the study indicate that gingival contact hypersensitivity to DNCB can be elicited in beagle dogs and that this reaction is reflected in crevicular parameters of gingival inflammation.     

Retrospective evaluation of the outcome of orthodontic treatment in adults

The aim of this study was the retrospective evaluation of the outcome of orthodontic treatment in consecutively treated adult patients. Of 147 adult patients, it was possible to evaluate the records of 88 patients (57 female, 31 male) before (T1) and after treatment (T2), and of 20 of these patients 3.3 years on average after completion of the retention phase (T3). During treatment planning, a nearly "ideal" result was considered attainable (ideal group) for 46 patients, and a "compromise" result (compromise group) was seen as realistic for 42. The assessment was made using the PAR (Peer Assessment Rating) index and the Aesthetic Component (AC) and Dental Health Components (DHC) of the IOTN (Index of Orthodontic Treatment Need). Average length of treatment in the ideal group was 2.4 years, i.e. nearly twice as long as in the compromise group. The PAR score was reduced by an average of 56% (T2); the reduction in the ideal group was 73%, and in the compromise group 37%. Among the 20 patients for whom at least 6 months had elapsed since completion of the retention phase, a statistically significant relapse between T2 and T3 was observed. The evaluation of overjet and overbite and, in the ideal group, of the midline and maxillary front teeth were primarily responsible for the worsening of the PAR scores between T2 and T3. According to the AC, 53 patients (60%) had moderate to definite treatment needs at the beginning of treatment. Following completion of active treatment, 69 patients (78%) no longer demonstrated treatment indications for aesthetic or psychosocial reasons. Based on the DHC, 88% of the patients were in definite or moderate need of treatment (T1); in contrast, treatment was no longer indicated in 84% at T2. In general, a marked improvement of the examined morphological parameters was observed.     

Clinical and radiographic evaluation, following delivery of fixed reconstructions, at GBR treated titanium fixtures

Conditions following incorporation of fixed reconstructions, at endosseous titanium implants augmented at local bony dehiscence and fenestration defects using a bioabsorbable Resolut® membrane were studied in 7 patients. Fixture stability, radiographic marginal bone levels and peri‐implant soft tissue status were evaluated at 2 1 membrane treated and 17 control fixtures (installed in regions of adequate bone volume), following a 2‐year period of functional loading. Prosthetic reconstructions were removed and clinical examination and Periotest values revealed that all fixtures were stable. All peri‐implant soft tissues were clinically healthy. The mean probing depths at buccal sites for fixtures with original dehiscence ( n =10) and fenestration ( n =11) defects were 1.6 ± 0.7 mm and 1.2 ± 0.4 mm respectively. The control fixture group had a mean buccal probing depth of 1.4 ± 0.6 mm. At abutment connection radiograph membrane treated fixtures had significantly lower marginal bone levels than control fixtures, indicating that optimal bone regeneration was not achieved at all defects. Mean radiographic bone loss 23–7 months following delivery of fixed reconstructions for original dehiscence and fenestration defect fixtures was 0.7 ± 0.8 mm and 0.8 ± 0.6 mm respectively at mesial surfaces, and 0.8 ± 0.7 mm and 0.6 ± 0.5 mm at distal surfaces. In the control fixture group a mean loss of 0.7 ± 0.5 mm at mesial surfaces and 0.5 ± 0.4 mm at distal surfaces was found. Results showed no significant difference in the rate of bone loss following functional loading between membrane treated and control fixtures.