Effect of evaporation of primer components on ultimate tensile strengths of primer-adhesive mixture.

OBJECTIVE: The purpose of the present study was to evaluate the effect of evaporation of primer components on the ultimate tensile strength (UTS) of primer-adhesive mixtures. METHODS: The UTSs of 1:3 by weight primer-adhesive mixtures and of the pure adhesives (controls) were measured after 0-, 2-, 5-min and 24-h storage in a 37 degrees C oven for the three-step etch&rinse adhesive OptiBond FL (Kerr) and the two-step self-etch adhesive Clearfil SE (Kuraray). RESULTS: Evaporation of primer components increased with time for both adhesives investigated. OptiBond FL showed a higher evaporation of primer components than Clearfil SE at the 2-, 5-min and 24-h storage time. As compared to the pure adhesive, the UTS of the primer-adhesive mixture was lower after 0- and 2-min storage for OptiBond FL and after 0-, 2- and 5-min storage for Clearfil SE. The UTS of OptiBond FL was higher than that of Clearfil SE at the 0- and 2-min storage time, though there was no difference at the 5-min and 24-h storage time. SIGNIFICANCE: The degree of evaporation of primer components depended largely on the primer solvents employed. The significant decrease in UTS of adhesive resin when mixed with primer must be attributed to incomplete evaporation of primer components. Complete evaporation of solvents is hard to achieve, even by thorough air drying.     

The influence of Bio-Oss Collagen on healing of an extraction socket: an experimental study in the dog

The objective of the present experiment was to evaluate the effect on hard tissue modeling and remodeling of the placement of a xenograft in fresh extraction sockets in dogs. Five mongrel dogs were used. Two mandibular premolars (4P4) were hemisected in each dog, and the distal roots were carefully removed. In one socket, a graft consisting of Bio-Oss Collagen (Geistlich) was placed, whereas the contralateral site was left without grafting. After 3 months of healing, the dogs were euthanized and biopsies sampled. From each experimental site, four ground sections (two from the mesial root and two from the healed socket) were prepared, stained, and examined under the microscope. The presence of Bio-Oss Collagen failed to inhibit the processes of modeling and remodeling that took place in the socket walls following tooth extraction. However, it apparently promoted de novo hard tissue formation, particularly in the cortical region of the extraction site. Thus, the dimension of the hard tissue was maintained and the profile of the ridge was better preserved. The placement of a biomaterial in an extraction socket may promote bone modeling and compensate, at least temporarily, for marginal ridge contraction.     

Quantitative longitudinal study of alveolar bone tissue in man

This investigation concerns the reaction of alveolar interdental tissue to periodontal surgery as observed from radiopacity changes in the region studied. The radiopacity of the tissue was determined with the aid of an Iodine¹²⁵ apparatus for intraoral measurements. The radiation source is small and the energy is 27.4 keV. The precision of the method was tested over the period of investigation and found to be high. Seven flap operations were performed on four patients with periodontal disease. The radiopacity of the alveolar tissue after operation seems to bedependent on changes caused by the postoperative edema of the soft tissue, resulting in an increase in radiopacity, and changes caused by mineralization processes in the alveolar bone. A demineralization of the interdental bone is observed from about two weeks after operation and reaching its lowest value within six weeks after operation. Thereafter a secondary increase in radiopacity is recorded. This is interpreted as a remineralization of the alveolar bone.     

The effects of a calorie-reduced diet on periodontal inflammation and disease in a non-human primate model

BACKGROUND: Low-calorie diets are commonplace for reducing body weight. However, no information is available on the effects of a reduced-calorie diet on periodontal inflammation and disease. The purpose of this study was to evaluate the clinical effects of a long-term calorie-restriction (CR) diet on periodontitis in an animal model of periodontitis. METHODS: Periodontitis was induced in 55 young, healthy, adult rhesus monkeys (Macaca mulatta) by tying 2.0 silk ligatures at the gingival margins of maxillary premolar/molar teeth. Animals on a CR diet (30% CR; N = 23) were compared to ad libitum diet controls (N = 32). Clinical measures, including the plaque index (PI), probing depth (PD), clinical attachment level (CAL), modified gingival index (GI), and bleeding on probing (BOP) were recorded at baseline and 1, 2, and 3 months after ligature placement. RESULTS: Significant effects of CR were observed on the development of inflammation and the progression of periodontal destruction in this model. Compared to controls, CR resulted in a significant reduction in ligature-induced GI (P <0.0001), BOP (P <0.0015), PD (P <0.0016), and CAL (P <0.0038). Periodontal destruction, as measured by CAL, progressed significantly more slowly in the CR animals than in the controls (P <0.001). CONCLUSIONS: These clinical findings are consistent with available evidence that CR has anti-inflammatory effects. Moreover, these experimental findings are the first observations, to the best of our knowledge, that CR dampens the inflammatory response and reduces active periodontal breakdown associated with an acute microbial challenge.     

Utilisation of locally delivered doxycycline in non-surgical treatment of chronic periodontitis

AIM: In the present 6-month multicentre trial, the outcome of 2 different approaches to non-surgical treatment of chronic periodontitis, both involving the use of a locally delivered controlled-release doxycycline, was evaluated. MATERIAL AND METHODS: 105 adult patients with moderately advanced chronic periodontitis from 3 centres participated in the trial. Each patient had to present with at least 8 periodontal sites in 2 jaw quadrants with a probing pocket depth (PPD) of > or =5 mm and bleeding following pocket probing (BoP), out of which at least 2 sites had to be > or =7 mm and a further 2 sites > or =6 mm. Following a baseline examination, including assessments of plaque, PPD, clinical attachment level (CAL) and BoP, careful instruction in oral hygiene was given. The patients were then randomly assigned to one of two treatment groups: scaling/root planing (SRP) with local analgesia or debridement (supra- and subgingival ultrasonic instrumentation without analgesia). The "SRP" group received a single episode of full-mouth supra-/subgingival scaling and root planing under local analgesia. In addition, at a 3-month recall visit, a full-mouth supra-/subgingival debridement using ultrasonic instrumentation was provided. This was followed by subgingival application of an 8.5% w/w doxycycline polymer at sites with a remaining PPD of > or =5 mm. The patients of the "debridement" group were initially subjected to a 45-minute full-mouth debridement with the use of an ultrasonic instrument and without administration of local analgesia, and followed by application of doxycycline in sites with a PPD of > or =5 mm. At month 3, sites with a remaining PPD of > or =5 mm were subjected to scaling and root planing. Clinical re-examinations were performed at 3 and 6 months. RESULTS: At 3 months, the proportion of sites showing PPD of < or =4 mm was significantly higher in the "debridement" group than in the "SRP" group (58% versus 50%; p<0.05). The CAL gain at 3 months amounted to 0.8 mm in the "debridement" group and 0.5 mm in the "SRP" group (p=0.064). The proportion of sites demonstrating a clinically significant CAL gain (> or =2 mm) was higher in the "debridement" group than in the "SRP" group (38% versus 30%; p<0.05). At the 6-month examination, no statistically significant differences in PPD or CAL were found between the two treatment groups. BoP was significantly lower for the "debridement" group than for the "SRP" group (p<0.001) both at 3- and 6 months. The mean total treatment time (baseline and 3-month) for the "SRP" patients was 3:11 h, compared to 2:00 h for the patients in the "debridement" group (p<0.001). CONCLUSION: The results indicate that simplified subgingival instrumentation combined with local application of doxycycline in deep periodontal sites can be considered as a justified approach for non-surgical treatment of chronic periodontitis.     

Effect of nonsurgical periodontal therapy

Abstract Healing events after nonsurgical periodontal therapy in patients with periodontal pockets 4–7 mm deep were investigated. Incisors, cuspids and premolars in 15 patients were treated by plaque control and supra- and subgingival debridement using hand or ultrasonic instruments in a split mouth approach. The results were evaluated by recordings of plaque scores, bleeding on probing, probing pocket depths and probing attachment levels. All these parameters were improved during the initial 4–5 months after start of therapy. Little change occurred during the rest of the 13-month observation period. No difference of results could be observed comparing hand and ultrasonic instrumentation or comparing the results of two different operators. Initially a total of 106 sites demonstrated probing pocket depths ≥ 6 mm. At 13 months only 13 such sites were observed. The apparently successful results of conservative treatment of patients with 4–7 mm deep pockets in the present study raise the question to what extent nonsurgical therapy is feasible also in patients with severely advanced lesions.     

Effect of experimental leukopenia on chronic gingival inflammation in dogs

Leukopenia was induced in six beagle dogs with chronic gingivitis by the injection of heterologous anti-neutrophil scrum. During leukopenia, the number of neutrophils in the gingival crevice and within the gingival tissues was reduced. Concomitant with the reduction of neutrophils, the amount of gingival fluid decreased. The activity of acid phosphatase, hyaluronidase and protease in crevicular samples was determined and was found to decrease in parallel with the reduction in neutrophil number. All parameters returned to normal during the post-leukopenic period. The results of the present study support previous suggestions that neutrophils at the dento-gingival junction contribute to the enzyme milieu in the gingival crevice and that these cells, through their lysosomal enzymes, may induce vascular damage in periodontitis.