Impact of smoking on experimental gingivitis. A clinical, microbiological and immunological prospective study.

OBJECTIVE: The present study assessed the effect of smoking on clinical, microbiological and immunological parameters in an experimental gingivitis model. MATERIAL AND METHODS: Twenty-four healthy dental students were divided into two groups: smokers (n = 10); and nonsmokers (n = 14). Stents were used to prevent biofilm removal during brushing. Visible plaque index (VPI) and gingival bleeding index (GBI) were determined 5- on day -7 (running phase), baseline, 21 d (experimental gingivitis) and 28 d (resolution phase). Supragingival biofilm and gingival crevicular fluid were collected and assayed by checkerboard DNA-DNA hybridization and a multiplex analysis, respectively. Intragroup comparison was performed by Friedman and Dunn's multiple comparison tests, whereas the Mann-Whitney U-test was applied for intergroup analyses. RESULTS: Cessation of oral hygiene resulted in a significant increase in VPI, GBI and gingival crevicular fluid volume in both groups, which returned to baseline levels 7 d after oral hygiene was resumed. Smokers presented lower GBI than did nonsmokers (p < 0.05) at day 21. Smokers had higher total bacterial counts and higher proportions of red- and orange complex bacteria, as well as lower proportions of Actinomyces spp., and of purple- and yellow-complex bacteria (p < 0.05). Furthermore, the levels of key immune-regulatory cytokines, including interleukin (IL)-8, IL-17 and interferon-γ, were higher in smokers than in nonsmokers (p < 0.05). CONCLUSION: Smokers and nonsmokers developed gingival inflammation after supragingival biofilm accumulation, but smokers had less bleeding, higher proportions of periodontal pathogens and distinct host-response patterns during the course of experimental gingivitis.

Alcohol intake may impair bone density and new cementum formation after enamel matrix derivative treatment: histometric study in rats.

BACKGROUND AND OBJECTIVE: Alcohol intake may interfere with bone metabolism; however, there is a lack of information about the outcomes of regenerative approaches in the presence of alcohol intake. Enamel matrix derivative (EMD) has been used in periodontal regenerative procedures resulting in improvement of clinical parameters. Thus, the aim of this histomorphometric study is to evaluate the healing of periodontal defects after treatment with EMD under the influence of alcohol intake. MATERIAL AND METHODS: Twenty Wistar rats were randomly assigned to two groups: G1 = alcohol intake (n = 10) and G2 = non-exposed to alcohol intake (n = 10). Thirty days after initiation of alcohol intake, fenestration defects were created at the buccal aspect of the first mandibular molar of all animals from both groups. After the surgeries, the defects of each animal were randomly assigned to two subgroups: non-treated control and treated with EMD. The animals were killed 21 d later. RESULTS: G1 showed less defect fill for non-treated controls. Bone density (BD) and new cementum formation were lower for G1 when compared to G2, for EMD-treated and non-treated sites. EMD treatment resulted in greater BD and new cementum formation in both groups and defect fill was not significantly different between groups in the EMD-treated sites. The number of tartrate-resistant acid phosphatase-positive osteoclasts was significantly higher in G1 when compared to G2 and in EMD-treated sites of both groups. CONCLUSION: Alcohol intake may produce a significant detrimental effect on BD and new cementum formation, even in sites treated with EMD. A limited positive effect may be expected after EMD treatment under this condition.

Cigarette smoke inhalation increases the alveolar bone loss caused by primary occlusal trauma in a rat model.

BACKGROUND AND OBJECTIVE: Occlusal trauma (OT) and smoking are both factors that alter alveolar bone metabolism and therefore could synergistically act on alveolar bone loss. The aim of this experimental study was to evaluate the influence of short-term cigarette smoke inhalation (CSI) on inter-radicular alveolar bone loss promoted by primary OT in a rat model. MATERIAL AND METHODS: Forty-eight animals were randomly assigned to one of three groups based on treatment type: OT + CSI (n = 16), animals were exposed to CSI three times per day, for 8 min per exposure, and they concomitantly received unilateral vertical augmentation creating an occlusal interference inducing experimental OT; OT (n = 16), animals received only unilateral vertical augmentation; negative control (NC; n = 16), animals maintained for equal periods to achieve periodontal baseline values of periodontal ligament dimension. Each group was divided into two subgroups (n = 8) based on treatment length: 7 or 14 d. RESULTS: After 7 d, the OT + CSI group exhibited significantly higher bone loss compared to the NC group (p = 0.0022). After 14 d, the OT (p < 0.0001) and OT + CSI (p < 0.0001) groups presented significantly higher bone loss compared to the NC group, and OT + CSI resulted in significantly higher bone loss than OT alone (p = 0.0241). The number of tartrate-resistant acid phosphatase-positive cells on the linear surface of the bone crest after 7 d was significantly higher in the OT + CSI group as compared to the NC and OT groups (p < 0.0001 and p = 0.0045, respectively) and remained significantly higher in the OT + CSI group after 14 d, compared to the OT group (p < 0.0001). CONCLUSION: Short-term CSI increases early bone loss in association with OT after 7 d, and this worsens in severity after 14 d of exposure.

Subgingival biodiversity in subjects with uncontrolled type-2 diabetes and chronic periodontitis.

BACKGROUND AND OBJECTIVE: There is a bidirectional relationship between periodontal disease and type-2 diabetes mellitus (DM). Inflammatory mediators may negatively affect glycemic control, and increased glucose levels and resultant glycation end-products may alter the host response against bacterial infection. However, no agreement has been reached regarding the effect of DM on periodontal subgingival microbiota. Therefore, the purpose of the present study was to compare the subgingival biodiversity in deep periodontal pockets of subjects with chronic periodontitis and either uncontrolled type-2 diabetes or no diabetes using 16S rRNA gene cloning and sequencing. MATERIAL AND METHODS: Twelve subjects with uncontrolled type-2 diabetes (glycated hemoglobin > 8%) and eleven nondiabetic subjects presenting severe and generalized chronic periodontitis were selected. Subgingival biofilm from periodontal pockets > 5 mm were assessed using the 16S rRNA gene cloning and sequencing technique. RESULTS: Significant differences were observed in subgingival microbiota between diabetic and nondiabetic subjects. Diabetic subjects presented higher percentages of total clones of TM7, Aggregatibacter, Neisseria, Gemella, Eikenella, Selenomonas, Actinomyces, Capnocytophaga, Fusobacterium, Veillonella and Streptococcus genera, and lower percentages of Porphyromonas, Filifactor, Eubacterium, Synergistetes, Tannerella and Treponema genera than nondiabetic individuals (p < 0.05). Moreover, some phylotypes, such as Fusobacterium nucleatum, Veillonella parvula, V. dispar and Eikenella corrodens were detected significantly more often in diabetic subjects than in nondiabetic subjects (p < 0.05). CONCLUSION: Subjects with uncontrolled type-2 diabetes and chronic periodontitis presented significant dissimilarities in subgingival biodiversity compared with nondiabetic subjects.

Effect of autologous bone marrow-derived cells associated with guided bone regeneration or not in the treatment of peri-implant defects.

This study investigated the effect of bone marrow-derived cells associated with guided bone regeneration in the treatment of dehiscence bone defects around dental implants. Iliac-derived bone marrow cells were harvested from dogs and phenotypically characterized with regard to their osteogenic properties. After teeth extraction, three implant sites were drilled, dehiscences created and implants placed. Dehiscences were randomly assigned to: bone marrow-derived cells, bone marrow-derived cells+guided bone regeneration, and control (no treatment). After 3 months, implants with adjacent tissues were processed histologically, bone-to-implant contact, bone fill within the threads, new bone area in a zone lateral to the implant, new bone height, and new bone weight at the bottom of the defect were determined. Phenotypic characterization demonstrated that bone marrow-derived cells presented osteogenic potential. Statistically higher bone fill within the threads was observed in both bone marrow-derived cells+guided bone regeneration bone marrow-derived cell groups compared with the control group (P<0.05), with no difference between the groups treated with cells (P>0.05). For the other parameters (new bone area, bone-to-implant contact, new bone height and new bone weight), only the bone marrow-derived cells+guided bone regeneration group presented higher values compared with the non-treated control (P<0.05). Bone marrow-derived cells provided promising results for peri-implantar bone regeneration, although the combined approach seems to be relevant, especially to bone formation out of the implant threads.

Impact of Porphyromonas gingivalis inoculation on ligature-induced alveolar bone loss. A pilot study in rats.

BACKGROUND AND OBJECTIVE: Periodontitis is a polymicrobial infection characterized by the loss of connective tissue attachment, periodontal ligament and alveolar bone. The aim of this study was to evaluate the impact of Porphyromonas gingivalis inoculation on the ligature-induced alveolar bone loss (ABL) model in rats. MATERIAL AND METHODS: Forty male Wistar rats were randomly assigned to the following groups: G1, control (n = 10); G2, ligature-induced ABL (n = 15); and G3, ligature-induced ABL + P. gingivalis inoculation (n = 15). Rats in G2 and G3 were killed 15, 21 and 30 d after ligature placement, and the following parameters were assessed: microbiological load; ABL; and interleukin (IL)-1ß (Il1beta)/Il1ra, Il6/Il10 and Rankl/osteoprotegerin (Opg) mRNA ratios in the gingival tissues, as determined by quantitative PCR. RESULTS: Microbiological analyses demonstrated that rats in G1, G2 and G3 were positive for the presence of bacteria (determined using PCR amplification of the 16S gene), but that only the treatment sites of rats in G3 were positive for P. gingivalis at all time-points investigated. Histometrically, significant bone loss (p<0.001) was observed for both ligated groups (G2 and G3) compared with the nonligated group (G1), with higher ABL observed for G2 at all the experimental time-points. Furthermore, gene-expression analysis demonstrated that the presence of P. gingivalis in the dentogingival area significantly decreased the Il1ß/Il1ra, Il6/Il10 and Rankl/Opg mRNA ratios compared with ligature alone. CONCLUSION: Within the limits of this pilot study, it was concluded that inoculation of P. gingivalis affected the ligature-induced ABL model by the induction of an anti-inflammatory and antiresorptive host response.

The influence of thyroid hormones on periodontitis-related bone loss and tooth-supporting alveolar bone: a histological study in rats.

BACKGROUND AND OBJECTIVE: Recent studies have pointed to potentially periodontal risk indicators, however no information is available on the impact of changes in thyroid hormone levels on the progression of periodontitis and on the quality of alveolar bone. Thus, the aim of the present study was to evaluate histologically, in rats, the influence of thyroid hormones on the rate of periodontal bone loss resulting from ligature placement and on the quality of tooth-supporting alveolar bone. MATERIAL AND METHODS: Thirty-six male Wistar rats were randomly assigned to the following groups: healthy (control, n = 12), hypothyroidism (n = 12) and hyperthyroidism (n = 12). Once alterations were confirmed by total serum levels of triiodothyronine and thyroxine, ligatures were randomly placed around one of the first mandibular molars. Thirty days later, the animals were killed and specimens routinely processed for serial decalcified sections. The parameters assessed were periodontitis-related bone loss, quality of tooth-supporting alveolar bone and the number of cells positive for tartrate-resistant acid phosphatase (TRAP), a marker of bone resorption. RESULTS: At the ligated sites, intergroup analysis revealed that hypothyroidism significantly increased the bone loss resulting from ligature-induced periodontitis (p = 0.02) and the number of TRAP-positive cells on the linear surface of bone crest (p = 0.01). In addition, no significant differences were detected regarding the quality of the bone (p = 0.24) or the number of TRAP-positive cells in the area of the interradicular bone for ligated teeth among the groups (p = 0.17). CONCLUSION: It may be concluded that decreased serum levels of thyroid hormones may enhance periodontitis-related bone loss, as a function of an increased number of resorbing cells, whereas the tooth-supporting alveolar bone seems to be less sensitive to alterations in hormone levels.

Guided tissue regeneration may modulate gene expression in periodontal intrabony defects: a human study.

BACKGROUND AND OBJECTIVE: Guided tissue regeneration has been shown to lead to periodontal regeneration, however, the mechanisms involved remain to be clarified. The present study was carried out to assess the expression of genes involved in the healing process of periodontal tissues in membrane-protected vs. nonprotected intrabony defects in humans. MATERIAL AND METHODS: Thirty patients with deep intrabony defects (> or = 5 mm, two or three walls) around teeth that were scheduled for extraction were selected and randomly assigned to receive one of the following treatments: flap surgery alone (control group) or flap surgery plus guided tissue regeneration (expanded polytetrafluorethylene (e-PTFE) membrane) (test group). Twenty-one days later, the newly formed tissue was harvested and quantitatively assessed using the polymerase chain reaction assay for the expression of the following genes: alkaline phosphatase, receptor activator of nuclear factor-kappa B ligand, osteoprotegerin, osteopontin, osteocalcin, bone sialoprotein, basic fibroblast growth factor, interleukin-1, interleukin-4, interleukin-6, matrix metalloproteinase-2 and matrix metalloproteinase-9. RESULTS: Data analysis demonstrated that mRNA levels for alkaline phosphatase, receptor activator of nuclear factor-kappa B ligand, osteoprotegerin, osteopontin, bone sialoprotein, basic fibroblast growth factor, interleukin-1, interleukin-6, matrix metalloproteinase-2 and matrix metalloproteinase -9 were higher in the sites where guided tissue regeneration was applied compared with the control sites (p < 0.05), whereas osteocalcin mRNA levels were lower (p < 0.05). No difference was observed in interleukin-4 mRNA levels between control and test groups. CONCLUSION: Within the limits of this study, it can be concluded that genes are differentially expressed in membrane barrier-led periodontal healing when compared with flap surgery alone, and this may account for the clinical outcome achieved by guided tissue regeneration.

Diabetes modulates gene expression in the gingival tissues of patients with chronic periodontitis.

AIM: This study evaluated whether diabetes modulates gene expression [interleukin (IL)-1beta, IL-1ra, IL-6, IL-8, IL-10; tumor necrosis factor (TNF)-alpha; interferon (IFN)-gamma, receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin (OPG)] in sites with periodontitis. MATERIALS AND METHODS: Gingival biopsies were harvested and divided into three groups--Control group: systemically and periodontally healthy subjects (n = 10); Periodontitis group: systemically healthy subjects diagnosed with chronic periodontitis (n = 20); Diabetes group: type 1 diabetic subjects, diagnosed with chronic periodontitis (n = 20). Total RNA was obtained and analyzed by quantitative polymerase chain reaction. RESULTS: Data analysis demonstrated that, except for OPG, mRNA levels for all factors were increased by inflammation (P < 0.001). Interleukin-1beta, IL-1ra, IL-6, IL-8, IFN-gamma, and RANKL mRNA levels were higher in the diabetic group when compared with the control non-periodontitis group (P < 0.05), whereas IL-10 and OPG were lower (P < 0.05). No difference was observed for TNF-alpha between diabetic and control groups (P > 0.05). Diabetes lowered IL-1beta, IL-8, IL-10, TNF-alpha, RANKL, and OPG mRNA levels in sites with comparable type of periodontitis (P < 0.001). Moreover, increased RANKL:OPG and IL-6:IL-10 ratios were found. CONCLUSION AND CLINICAL RELEVANCE: Taken together, these data suggest that decreased levels of IL-10 and OPG may play an important role in the periodontal breakdown in diabetic patients.

Smoking modulates interleukin-6:interleukin-10 and RANKL:osteoprotegerin ratios in the periodontal tissues.

BACKGROUND AND OBJECTIVE: This study evaluated the effect of smoking on the gene expression of interleukin-1alpha, -1ra, -6, -8 and -10, tumor necrosis factor-alpha, matrix metalloproteinase (MMP)-2 and -8, receptor activator of NF-kappaB ligand (RANKL) and osteoprotegerin, in sites with periodontitis. MATERIAL AND METHODS: Gingival biopsies were divided into three groups: the healthy group (periodontally healthy subjects; n=10); the periodontitis group [subjects with severe chronic periodontitis who never smoked (probing depth>or=7 mm) (n=25)]; and the smoking group (subjects diagnosed with severe chronic periodontitis who smoked>or=1 pack per day for at least 10 years; n=25). Gene and protein expressions were analyzed by quantitative polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. RESULTS: Data analysis demonstrated that, except for MMP-8 and osteoprotegerin, the levels of all factors were increased by inflammation (p<0.001). The levels of interleukin-1alpha, -1ra, -6 and -8, and RANKL, were higher in smokers with periodontitis compared with controls, whereas the levels of interleukin-10, MMP-8 and osteoprotegerin were lower (p<0.001). Smoking lowered the levels of interleukin-1alpha, -8, -10, tumor necrosis factor-alpha, MMP-8 and osteoprotegerin, and increased the levels of interleukin-6 and -1ra in sites with a comparable type of periodontitis (p<0.001). CONCLUSION: In conclusion, smoking modulates gene expression in the periodontium, and the influence of smoking on periodontal disease may involve effects of interleukin-6:interleukin-10 and RANKL:osteoprotegerin ratios.

Platelet-rich plasma does not improve bone regeneration around peri-implant bone defects--a pilot study in dogs.

The purpose of the present study was to evaluate the influence of platelet-rich plasma (PRP) on bone regeneration in dehiscence-type bone defects around dental implants. Ten male adult mongrel dogs were used. Three months after teeth extractions, an osteotomie for implantation and a buccal dehiscence defect were prepared on both sides of the jaws. Two dental implants with machined surfaces were placed on each implant site of the mandible. Dehiscences were randomly assigned to the following groups: (1) test (PRP) and (2) control. After 3 months animals were sacrificed; implants and adjacent hard tissues were processed for undecalcified sections. Bone-to-implant contact (BIC), bone density (BD) within the limits of implant threads, bone density (BO) and new bone area (NB) in a zone lateral to the implant, corresponding to bone defects, were obtained and measured. Inter group analysis (paired Student's t-test, alpha = 5%) demonstrated no statistically significant differences for any of the parameters when PRP was used (P > 0.05). Within the limits of the present study, it was concluded that platelet-rich plasma alone did not enhance bone regeneration for peri-implant defects.

Effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration: a histomorphometric study in dogs.

BACKGROUND AND OBJECTIVE: The aim of the present study was to evaluate comparatively the effect of two different approaches for root decontamination on new cementum formation following guided tissue regeneration (GTR). MATERIAL AND METHODS: Nine mongrel dogs were used to obtain bilateral chronic class III furcation defects by placing cotton ligatures around both third mandibular premolars. The teeth were randomly assigned to receive one of the following treatments: scaling and root planing, by means of hand and rotatory instruments, in order to remove soft and hard deposits as well as all root cementum (group A); or removal of only soft microbial deposits, by polishing the root surface with rubber cups and polishing paste, aiming for maximum root cementum preservation (group B). Both groups were treated with GTR, with the use of resorbable polyglycolic-lactic acid membranes (RESOLUT XT). RESULTS: Four months later, data analysis showed that a superior length (mm) (3.59 +/- 1.67 and 6.20 +/- 2.26 for groups A and B, respectively; p = 0.004) and a thicker layer (microm) (18.89 +/- 9.47 and 52.29 +/- 22.48 for groups A and B, respectively; p = 0.001) of new cementum was achieved by keeping the root cementum in place during root decontamination (group B). Regardless of the treatment modality, the new cementum was predominantly of a reparative, cellular extrinsic and intrinsic fiber type. CONCLUSION: Within the limits of the present study, it may be concluded that root cementum preservation may affect the new cementum formation following GTR in class III furcation defects, and the treatment modality did not influence the type of newly formed cementum.

Estrogen and alendronate therapies may prevent the influence of estrogen deficiency on the tooth-supporting alveolar bone: a histometric study in rats.

BACKGROUND AND OBJECTIVE: The aim of this study was to evaluate histometrically the influence of estrogen deficiency, and its therapies, on the quality of the tooth-supporting alveolar bone. MATERIAL AND METHODS: Seventy-three female rats were randomly assigned to one of the following groups: group 1 (n = 15), sham surgery; group 2 (n = 15), bilateral ovariectomy (OVX); group 3 (n = 14), OVX plus calcitonin (16 IU/kg); group 4 (n = 14), OVX plus estrogen (20 microg/kg); and group 5 (n = 15), OVX plus alendronate (5 mg/kg). Eighty days after surgery, the animals were killed and their mandibles were removed and processed for histology. Bone density (BD) in the furcation area of the first mandibular molar (i.e. the percentage of demineralized bone tissue in a 1,000 microm zone under the furcation) was histometrically obtained. RESULTS: Data analysis demonstrated that estrogen deficiency negatively affected the tooth-supporting bone density (79.45% +/- 4.22 and 55.23% +/- 6.45, for groups 1 and 2, respectively), and that estradiol and alendronate therapies prevented this effect (61.67% +/- 6.87, 78.09% +/- 3.12 and 81.47% +/- 4.58, for groups 3, 4 and 5, respectively). CONCLUSION: Within the limits of this study, it can be concluded that the density of tooth-supporting bone is affected by estrogen deficiency, and that estradiol and alendronate therapies, but not calcitonin, provide protection against this effect.

Periodontal healing may be affected by aging: a histologic study in rats.

BACKGROUND AND OBJECTIVE: Although wound healing has been reported to be impaired with aging, very little is known about its effect on periodontal tissues. Therefore, the aim of this study was to evaluate, histologically in rats, the influence of aging on a spontaneous periodontal healing model. MATERIAL AND METHODS: Twenty-four male Wistar rats were used and assigned to the following groups: control (n = 12; 2 mo old) and aged (n = 12; 18 mo old). Fenestration defects (4 x 3 x 1 mm) were created bilaterally at the buccal aspect of the distal root of the first mandibular molars, and the mandibulae were retrieved 3 and 6 wk postoperatively. The percentage of bone fill and density of newly formed bone, new cementum formation (NC), and the extension of the remaining defect (ERD) were histometrically obtained. RESULTS: Intragroup analysis demonstrated that, except for cementum, all histological parameters significantly improved over time (p < 0.05). Intergroup analysis additionally showed that the defects were initially similar in size, and that at 3 wk aging negatively influenced newly formed bone (86.38 +/- 2.99% and 73.06 +/- 3.21%, p < 0.001, for groups control and aged, respectively), BF (75.84 +/- 16.53% and 57.70 +/- 22.28%, p = 0.014) and ERD (0.41 +/- 0.20 mm and 1.17 +/- 0.37 mm, p < 0.001). At 6 wk, aging negatively influenced newly formed bone (88.12 +/- 2.90% and 78.19 +/- 5.35%, p < 0.001, for groups control and aged, respectively) and ERD (0.01 +/- 0.006 mm and 0.34 +/- 0.18 mm, p = 0.003), but not BF (98.15 +/- 2.43% and 87.87 +/- 11.63%, p > 0.05). No new cementum was formed along the root surface in the above groups. CONCLUSION: Within the limits of the present study, data analysis suggests that aging may impair, but not prevent, periodontal healing.

Long-term results of guided tissue regeneration therapy in the treatment of class II furcation defects: a randomized clinical trial.

BACKGROUND: The purpose of this study was to evaluate the results after guided tissue regeneration (GTR) using a bioabsorbable membrane in Class II furcation defects in mandibular molars over a 24-month period. METHODS: Nine patients with 2 comparable Class II furcation defects were included. The defects in each patient were randomly assigned to either test (GTR) or control (open flap debridement) group. Clinical measurements and standardized radiographs were taken at baseline, and at 6, 12, 18, and 24 months. The radiographs were analyzed by subtraction radiography. RESULTS: There were significant probing depth reductions for both test and control groups (P < 0.007, P < 0.0005, respectively); however the differences between groups were not significant at any examination. The intra-group and inter-group differences in the vertical clinical attachment level gain were not significant (P > 0.05). Over 24 months, a significant horizontal clinical attachment level gain was observed in the test group compared to control (P<0.03). In the test group, 2 sites showed complete closure, one was converted to Class I, and one tooth was lost due to root resorption. In the control group, 2 defects progressed to Class III over 24 months. At 6 months, the test group showed 0.14 mm of bone loss while the control group showed 0.86 mm of bone gain (P = 0.035). The inter-group differences were not significant at 12, 18, and 24 months. A significant bone height gain was observed in the test group at 24 months when compared to the values obtained after 6 months (P = 0.015). CONCLUSION: GTR may provide a greater horizontal clinical attachment level gain with the possibility of complete closure of some defects and stability over time.

The effect of an immunosuppressive therapy and its withdrawal on bone healing around titanium implants. A histometric study in rabbits.

BACKGROUND: Immunosuppressive agents have been recognized as a factor affecting bone metabolism. We investigated the consequences of the administration and withdrawal of cyclosporin A/nifedipine on bone around titanium implants to observe whether these changes occur and if they are reversible. METHODS: Twenty-eight New Zealand rabbits were included in the study. Following anesthesia, the tibiae surface was exposed, and 2 screw-shaped implants 7.0 mm in length and 3.75 mm in diameter were placed bilaterally. The animals were randomly assigned to 1 of 4 experimental groups and received daily subcutaneous injections for 14 days: groups A and C were injected with vehicle while groups B and D received cyclosporin A (10 mg/kg) plus nifedipine (0.5 mg/kg). Groups A and B were sacrificed 14 days and groups C and D 42 days postoperatively. The degree of bone contact with the implant surface and the bone area within the limits of the threads of the implant were measured. RESULTS: Intergroup analysis revealed no significant difference (P > 0.05) in the degree of bone contact with the implant surface between the control and test groups on days 14 and 42. In contrast, the treated animals demonstrated a significant (P < 0.05) decrease in the bone area within the limits of the threads of the implant in both periods. CONCLUSIONS: The data of the present study suggest that the use of cyclosporin A/nifedipine may influence bone healing around titanium implants. This observation may have important clinical implications.

[Need of periodontal treatment evaluated with CPITN and its relation to the quality of the cervical margin of restorations]. / Necessidade de tratamento periodontal avaliada pelo CPITN e sua relação com a qualidade de acabamento cervical das restaurações.

Irregularities of the cervical margin of restorations facilitate the retention of bacterial plaque, hindering plaque control through the habitual procedures of oral hygiene and favoring the development of periodontal disease. The aim of this study was to evaluate the periodontal condition and treatment needs (applying CPITN) in relation to the cervical margin of dental restorations. Three hundred and sixty-seven teeth with class II and V cavities restored with amalgam, class III cavities restored with composite resin, cast metal restorations and unitary prostheses were examined. With a WHO periodontal probe, the position of the cervical margins of restorations was verified (supragingival, subgingival or at the gingival margin level); the presence of defects (lack or excess of restoring material) and the presence of score 2 of CPITN were also assessed. After the analysis of the data, it was possible to conclude that: 1) supragingival margins offered the best marginal adaptation and the lowest frequency of score 2; 2) both the lack and the excess of restoring material favor the development of score 2, despite the utilized material and 3) in subgingival margins, incorrect marginal adaptation was the most frequent event, mainly due to excess of restoring material, and in these cases there was higher frequency of score 2 of CPITN.

Effect of calcitonin on bone formation around titanium implant. A histometric study in rabbits.

Bone healing around titanium implants has already been evaluated; however, the effect of drugs such as calcitonin during the period of bone maturation around titanium implants has not yet been investigated. The purpose of this study was to evaluate the effects of calcitonin administration on the late period of bone healing following titanium implant insertion. Twenty-seven adult New Zealand rabbits received one implant in each femur. Thirteen animals were randomly selected as the test group (2 IU/kg--calcitonin) and fourteen animals served as control (saline). The animals were sacrificed 6, 8, 12 and 18 weeks after surgery. Endosteal/periosteal bone length (EB/PB), endosteal/periosteal bone area (EBA/PBA) and total cortical length (TCL) around the implants were analyzed. After 6, 8, 12 and 18 weeks, a positive time effect was strongly observed (P < 0.05). Considering the treatment factor, there was a positive effect of calcitonin on EBA and EB variables at 12 weeks and TCL at 18 weeks. In conclusion, the administration of salmon calcitonin to healthy animals may improve bone mass at the later stages of bone healing following titanium implant insertion.

Absorbable versus nonabsorbable membranes and bone grafts in the treatment of ligature-induced peri-implantitis defects in dogs: a histometric investigation.

The purpose of this study was to histometrically evaluate an absorbable collagen membrane (Bio-Gide) and a nonabsorbable polytetrafluoroethylene membrane (PTFE), associated with or without bone grafts, regarding "re-osseointegration" after treating ligature-induced peri-implantitis defects in dogs. All mandibular premolars were removed from five 2-year-old mongrel dogs. After 3 months of healing, 3 titanium implants were placed on each side of the mandible. Experimental peri-implantitis was induced with ligatures after abutment connection. Ligatures and abutments were removed after 1 month and the bone defects were randomly assigned to one of the following treatments; debridement alone (DB), debridement plus PTFE membrane associated with mineralized bone graft (Bio-Oss) (GBR+BG-I), debridement plus collagen membrane (Bio-Gide) associated with mineralized bone graft (GBR+BG-II), debridement plus PTFE membrane (GBR-I), debridement plus collagen membrane (GBR-II), or debridement plus mineralized-bone graft (BG). The dogs were sacrificed after 5 months. Data analysis did not reveal significant differences among the treatments regarding the percentage of bone-to-implant contact ("re-osseointegration") within the limits of the threads of the implant (P = .997). Thus, in the treatment of peri-implantitis, debridement alone as well as grafting alone had the same effect as did either membrane.

Clinical study of guided bone regeneration and/or bone grafts in the treatment of ligature-induced peri-implantitis defects in dogs.

This study evaluated, by clinical analysis, the hard tissue response following treatment of ligature-induced peri-implantitis defects in 5 dogs. The mandibular premolars were removed from both sides of the jaw. After 3 months of healing, two titanium implants were placed on each side of the mandible. Following abutment connection, 3 months later, experimental peri-implantitis was induced by the placement of cotton ligatures in a submarginal position. Ligatures and abutments were removed after one month and the bony defects were randomly assigned to one of the following treatments: debridement (DE), debridement plus guided bone regeneration (GBR), debridement plus mineralized bone graft (BG) and debridement plus guided bone regeneration associated with mineralized bone graft (GBR + BG). The peri-implant bone defects were clinically measured before and 5 months post-treatment. Results showed a higher percentage of vertical bone fill for GBR + BG (27.77 +/- 14.07) followed by GBR (21.78 +/- 16.19), BG (21.26 +/- 6.87), DE (14.03 +/- 5.6). However, there were no statistically significant differences between any of the treatments proposed (one way repeated measures analysis of variance, P = 0.265).