Periodontal healing after application of enamel matrix derivative in surgical supra/infrabony periodontal defects in rats with streptozotocin-induced diabetes.

BACKGROUND AND OBJECTIVE: Epidemiologic and clinical studies have indicated that diabetes is a risk factor for periodontal disease progression and healing. The aim of the present study was to evaluate short-term healing after enamel matrix derivative (EMD) application in combined supra/infrabony periodontal defects in diabetic rats. MATERIAL AND METHODS: Thirty male Wistar rats were initially divided into two groups, one with streptozotocin-induced diabetes and another one with healthy (non-diabetic) animals. Bony defects were surgically created on the mesial root of the first maxillary molars. After root surface planing and EDTA conditioning, EMD was applied to the roots at one side of the maxillae, while those on the contralateral sides were left untreated. Animals were killed 3 wk after surgery, and block sections were prepared for histologic and histomorphometric analysis. RESULTS: There was statistically significant more gingival recession in diabetic animals than in non-diabetic animals. The length of the junctional epithelium was significantly shorter in the EMD-treated sites in both diabetic and normoglycemic rats. Sulcus depth and length of supracrestal soft connective tissue showed no statistically significant differences between groups. In all animals, new bone formation was observed. Although new bone occurred more frequently in healthy animals, the extent of new bone was not significantly different between groups. In none of the teeth, a layer of new cementum was detectable. EMD had no influence on bone or cementum regeneration. Adverse reactions such as excessive inflammation due to bacterial root colonization, ankylosis and bone fractures were exclusively observed in diabetic animals, irrespective of EMD treatment. CONCLUSION: Within the limits of the present study, it can be concluded that periodontal healing was impaired in streptozotocin-induced diabetic rats. EMD had no beneficial effects on new bone and cementum formation during short-term healing in this defect model and could not ameliorate the adverse effects in the systemically compromised animals.

[Clinical dilemmas concerning immediate implants in the esthetic zone].

Teeth replacement in the esthetic zone is a considerable challenge. Dental implants are usually the preferred treatment alternative for tooth replacement. The present review discusses several clinical issues concerning implant placement in the esthetic area. It is still unclear whether raising a flap at the time of implant placement enhances alveolar crest remodeling. However, a flapless surgical procedure could avoid changes in the free gingival margin and maintain the the attached gingiva width. A submarginal approach not involving the free gingival margin can be applied to treat bone defects with the GBR technique. Implants should be placed as palatal as possible while maintaining optimal restoration emergence profile and the horizontal bone defect filled with a non resorbable material such as bovine bone mineral. Thick periodontal biotype and coronally positioned free gingival margin usually lead to better results. Immediate implant placement in presence of a periapical lesion may be performed, however, sites should be thoroughly debrided prior to implant placement.

Differential effects of prostaglandin E(2) and enamel matrix derivative on the proliferation of human gingival and dermal fibroblasts and gingival keratinocytes.

BACKGROUND AND OBJECTIVE: Elevated levels of prostaglandins contribute to periodontal destruction but can impair gingival healing by affecting local fibroblasts. Enamel matrix derivative (EMD) has beneficial effects on supporting and gingival tissues. We showed that prostaglandin E(2) (PGE(2) ) inhibits the proliferation of human gingival fibroblasts (hGFs) and that EMD stimulates it. Prostaglandins and EMD may also affect skin healing by targeting dermal fibroblasts (DFs). Thus, we compared the effects of these two agents on the proliferation of hGFs, human gingival keratinocytes (hGKs) and hDFs. MATERIAL AND METHODS: Cells from healthy human gingiva or skin were treated with PGE(2) and/or EMD, and proliferation was assessed by measuring cell number and DNA synthesis. RESULTS: In hGFs, PGE(2) (1 µm) inhibited proliferation while EMD stimulated it. When present together, EMD abolished the PGE(2) -induced inhibition. Serum increased (by a factor of 10) the amount of phosphorylated extracellular signal-regulated kinase (p-ERK), PGE(2) reduced it (by 70-80%) and EMD restored it when present with PGE(2). Prostaglandin E(2) stimulated cAMP production in hGFs while serum or EMD did not. Enamel matrix derivative stimulated hDF proliferation, but the inhibitory effect of PGE(2) was milder than with hGFs. When present together, EMD abolished the PGE(2) -induced inhibition. Enamel matrix derivative inhibited the proliferation of primary hGKs, but PGE(2) had no effect. Finally, we found that hDFs contained about five times less prostaglandin EP(2) receptor mRNA than hGFs, while hGKs contained none. CONCLUSION: Prostaglandin E(2) inhibits and EMD stimulates hGF proliferation via distinct pathways. The different sensitivities of hDFs and hGKs to PGE(2) can be explained by the levels of EP(2) expression.

Enamel matrix derivative induces the expression of tissue inhibitor of matrix metalloproteinase-3 in human gingival fibroblasts via extracellular signal-regulated kinase.

BACKGROUND AND OBJECTIVE: Periodontal disease is characterized by increased expression and activity of matrix metalloproteinases (MMPs) and insufficient expression/activity of their inhibitors, tissue inhibitors of matrix metalloproteinases (TIMPs). This altered MMP-TIMP balance results in progressive destruction of gingival and periodontal extracellular matrix. Enamel matrix derivative (EMD), clinically used for periodontal regeneration in a device called Emdogain, has been suggested to enhance gingival healing following periodontal procedures in humans. We previously showed that EMD increases the proliferation of human and rat gingival fibroblasts and protects them from tumor necrosis factor-induced apoptosis. In the present study, the modulation of MMP and TIMP expression by EMD was investigated. MATERIAL AND METHODS: Primary human gingival fibroblasts were treated in vitro with tumor necrosis factor, EMD or both in serum-free conditions, and RNA was analyzed with an extracellular matrix-focused microarray and quantitative real-time polymerase chain reaction. RESULTS: Microarray analysis showed detectable expression of MMP-1, MMP-2, MMP-3, MMP-7 and MMP-13, as well as TIMP-1 and TIMP-3 in untreated cells. There was no apparent regulation of the expression of MMP-2, MMP-7, MMP-13 and TIMP-1 by either tumor necrosis factor or EMD. In contrast, tumor necrosis factor significantly increased MMP-1 expression, and EMD reduced it when both agents were present. Also, EMD significantly induced TIMP-3 expression, an effect which was dependent on activation of extracellular signal-regulated kinase 1/2, since it was totally abolished by a selective extracellular signal-regulated kinase pathway inhibitor. CONCLUSION: These data suggest that EMD may affect gingival health by ways other than cell proliferation/survival, i.e. by stimulation of TIMP-3 production, which could improve the MMP-TIMP balance in gingival tissue and curb extracellular matrix destruction.

Tetracycline therapy for muscle atrophy due to immobilization.

Certain proteins such as matrix metalloproteinase -2(MMP-2) and heat shock protein 70(HSP-70) play a role during the degradation process. We hypothesized that tetracycline can be used to reduce tissue degradation in skeletal muscles exposed to immobilization. The right knee of old rats (20-months-old) was immobilized by a rigid external fixator (EF) device for 1, 2, 3 and 4 weeks. Aqueous Tetracycline solution was administrated 3 times a week, following 2 days after the EF was constructed. Control group I was immobilized for 3 weeks, did not receive tetracycline but did received saline injection, and control group II only received tetracycline for 3 weeks. MMP-2 and HSP-70 protein and mRNA levels in the gastrocnemius and soleus muscles were analyzed at the molecular level by RT-PCR and the protein level using SDS-PAGE gels and western blots. We have shown that rats treated by Tetracycline reduce the MMP-2 expression and HSP-70. Theses changes mainly occurred in type IIb and type IIa muscle fibers. Tetracycline administration has beneficial effect on expression of enzymes involved in protein degradation. This may suggest a protective effect on protein degradation during immobilization.

EGFR in Enamel Matrix Derivative-induced gingival fibroblast mitogenesis.

We previously reported that EMD (Enamel Matrix Derivative) induces proliferation of human gingival fibroblasts via activation of Extracellular Regulated Kinase (ERK), and this study assessed the possible mediatory role of EGFR (Epidermal Growth Factor Receptor) in this effect. Treatment of gingival fibroblasts with EMD resulted in tyrosine phosphorylation of the EGFR, as assessed by immunoblotting and ELISA, while EMD-induced ERK activation and thymidine incorporation were markedly inhibited (approximately 40-50%) by a specific EGFR tyrosine kinase inhibitor. Using appropriate inhibitors, we established that EMD-induced EGFR activation is largely due to shedding of HB-EGF (Heparin-binding EGF) from the cell membrane via a metalloproteinase-mediated process. Finally, the addition of PP1, a Src family inhibitor, abrogated both EGFR phosphorylation and ERK activation. Taken together, these results indicate that, at least in human gingival fibroblasts, EMD-induced ERK activation and proliferation are partially due to a Src-dependent, metalloproteinase-mediated transactivation of EGFR.

Enamel matrix derivative protects human gingival fibroblasts from TNF-induced apoptosis by inhibiting caspase activation.

Emdogain, a formulation of enamel matrix derivative (EMD), is used clinically for regeneration of the periodontium (tooth supporting tissues), but the molecular mechanisms of its action have not been elucidated. Several clinical studies suggested that EMD may also improve gingival healing after periodontal surgery and thus affect the fate of gingival fibroblasts (GFs). Since these cells are targets for local inflammatory mediators such as TNF, a pro-apoptotic cytokine, during the course of periodontal disease, we tested whether EMD protects human GFs (hGFs) from TNF-induced cytotoxicity. Quiescent primary hGFs were challenged with TNF (10-100 ng/ml) with or without EMD (100 microg/ml) pretreatment. Cell viability was assessed by neutral red staining, cell death by LDH release and apoptosis by caspase activity. Signaling pathways were evaluated by Western blotting and pharmacological inhibitors. TNF induced classical signs of apoptosis in hGFs, including typical cellular morphology and increased caspase activity. TNF-induced cytotoxicity was entirely caspase-dependent. Pretreatment (4-24 h) with EMD dramatically inhibited the activation of initiator and executioner caspases and enhanced hGF survival. Although TNF induced the activation of p38 MAPK, JNK, ERK and PI-3K signaling, these pathways were not crucial for EMD protection of hGFs. However, EMD increased the levels of c-FLIP(L), an anti-apoptotic protein located upstream of caspase activation. These data demonstrate, for the first time, that EMD protects hGFs from inflammatory cytokines and, together with our recent reports that EMD stimulates rat and human GF proliferation, could help explain the mechanisms whereby in vivo use of EMD promotes gingival healing.

Enamel matrix derivative stimulates human gingival fibroblast proliferation via ERK.

Emdogain, a formulation of Enamel Matrix Proteins, is used clinically for periodontal regeneration to stimulate PDL (periodontal ligament), cementum, and bone formation. Its effects on gingival fibroblasts and tissue have not been thoroughly studied. Therefore, we investigated the mechanisms by which Emdogain affects the cell cycle of human gingival fibroblasts. Without serum, Emdogain (50 microg/mL) induced human gingival fibroblast entry into the S phase and DNA synthesis, but not completion of the cell cycle. With low serum concentrations (0.2-0.5%), Emdogain synergistically induced completion of the cell cycle, resulting in increased cell numbers. The mitogenic response to Emdogain depended on Extracellular Regulated Kinase (ERK) activation, which occurred in two waves, peaking after 15 min and 4 to 6 hrs, since it was abolished by U0126, a specific MAPK inhibitor. Inhibition of the second wave was sufficient to abrogate mitogenesis. This study characterized the mitogenic effect of Emdogain on primary human gingival fibroblasts, its cooperation with serum growth factors, and the key mediatory role of the ERK cascade.

Expression of matrix metalloproteinase 2 and heat shock protein-72 in immobilized muscle in rats.

Metalloproteinases (MMPs) are proteolytic enzymes that function in the extracellular matrix to degrade connective tissues. While it is clear that certain induced skeletal muscle pathologies promote increased expression of MMP-2 and heat shock protein- 72 (HSP-72), the relationship between muscle disuse and expression of MMP-2 and HSP-72 in muscles is unknown. These experiments tested the hypothesis that knee immobilization induced expression of MMP-2 and HSP-72 is disuse-dependent in a way that short-term joint immobilization increases HSP-72 expression, whereas long-term joint immobilization increases MMP-2 expression in skeletal muscles. Male rats (8 months old) completed 1, 2, 3, and 4 weeks of knee joint immobilization. Muscle mRNA and protein levels of MMP-2 and HSP-72 were assessed in Gastrocnemius (Gast), Superficial and Deep Quadriceps, and Soleus (Sol) muscles by reverse transcriptase-polymerase chain reaction and western blotting, respectively. Results reveal that during the first two weeks of immobilization there is increased protein levels of HSP-72 and expression of mRNA of HSP-72 mainly in slow twitch muscle fibers. However, 3 and 4 weeks of joint immobilization increased both mRNA and protein levels of MMP-2 in skeletal muscles containing a high percentage of fast type II fibers (i.e., Gast and superficial quadriceps). These results support the hypothesis that different periods of muscle disuse induced different proteins expression, and that the influence of joint immobilization on the expression of HSP-72 in the short-term, and MMP-2 in the long ran is associated to fiber types.

In vitro effects of enamel matrix proteins on rat bone marrow cells and gingival fibroblasts.

Emdogain (EMD), a formulation of Enamel Matrix Proteins (EMP), is used clinically for periodontal regeneration, where it stimulates cementum formation and promotes gingival healing. In this study, we investigated the in vitro effects of EMD on rat bone marrow stromal cells (BMSC) and gingival fibroblasts (GF). EMD (at 25 micro g/mL) increased the osteogenic capacity of bone marrow, as evidenced by approximately three-fold increase in BMSC cell number and approximately two-fold increase in alkaline phosphatase (ALP) activity and mineralized nodule formation. The presence of EMD in the initial stages (first 48 hrs) of the culture was crucial for this effect. In contrast, EMD did not induce osteoblastic differentiation of GF (evidenced by lack of mineralization or ALP activity) but increased up to two-fold both their number and the amount of matrix produced. These in vitro data on BMSC and GF could explain the promotive effect of EMD on bone formation and connective tissue regeneration, respectively.

[Differential diagnosis and treatment strategies for peri-implant diseases].

UNLABELLED: The aim of this article is to discuss the requirements to prevent, intercept and treat the peri-implant diseases at different stages. The ethiology and pathogenesis of peri-implant disease is presented, followed by definition and characteristics of the two main entites: peri-implant mucositis and peri-implantitis. Data and concepts regarding various evaluation parameters, such as pocket probing depth, bleeding on probing, gingival and plaque scores, radiographic and mobility which should be used to assess the clinical status of the peri-implant environment are discussed. The detection and treatment of early pathogenic changes during regular recall maintenance visits can prevent peri-implant soft tissue inflammation and progressive bone loss. The biologic rationale and guidelines for therapeutic procedures aimed to prevent and arrest the Peri-implant Disease according to a maintenance system termed Comulative Interceptive Supportive Therapy (CIST) is presented. The CIST protocol includes as a first sequence mechanical antiseptic and antibiotic treatment to control ongoing infection. Following this, peri-implant bony lesion may be corrected by regenerative or resective surgical techniques. IN CONCLUSION: By continuing diagnosis during maintenance, developing peri-implant infections can be controlled successfully by providing mechanical, antiseptic, antibiotic and surgical supportive therapy, individually or combined.

Preprosthetic clinical crown lengthening procedures in the anterior maxilla.

Clinical crown lengthening procedures (CCLP) are used to enhance aesthetics and/or provide adequate tooth structure for placement and retention of a restoration while respecting the attachment apparatus. When restoration margins extend beyond the biologic width, inflammation and anatomic changes can develop. Anterior CCLP are indicated to increase the labial exposure of the clinical crown and/or the sound tooth structure coronal to the bone crest. Preservation of the interproximal papillae is mandatory to obtain desirable final results in the aesthetic region. This article illustrates various methods of CCLP used to achieve successful oral rehabilitation in the anterior maxilla.

Orthodontic tooth movement enhances bone healing of surgical bony defects in rats.

BACKGROUND: The question of whether the repair of an alveolar bony defect can be enhanced by orthodontic tooth movement was addressed. METHODS: Alveolar bone defects were created in 52 Wistar male rats anterior to both maxillary first molars. After 1 week of healing, orthodontic protraction was applied for 2 weeks on the right side, resulting in mesial tipping and displacement movement. Subsequently, a retention appliance was inserted for 1 week. The left side served as the untreated (control) group. Vital bone staining (procion brilliant red H-8) was administered before and after orthodontic traction. Histomorphometric analysis was performed on 62 hemimaxillae using UV confocal microscopy and an imaging program. The total area of the bony defect was divided into 4 equal quadrants, and the area of bony apposition in each quadrant was measured. RESULTS: The total area of bony apposition was 6.5-fold larger in the treated (26.41 x 10(4) +/- 28.92 x 10(4) microm2) than in the control group (4.07 x 10(4) +/- 2.82 x 10(4) microm2), approaching statistical significance (P = 0.065). The treated occlusal quadrants demonstrated highly significant (P= 0.010), greater bone apposition compared to the control group (13.8-fold) and to the treated apical quadrants (P= 0.04, 5-fold). CONCLUSIONS: This study confirms that orthodontic tooth movement is a stimulating factor of bone apposition. A conversion in the repair pattern of the bony defect from apicoocclusal in the control group (no tooth movement) to occlusoapical in the treated group (with tooth movement) further supports the linkage between tooth movement and enhanced bone deposition. Clinical implication suggests incorporation of orthodontic tooth movement in regenerative therapy.

Histopathological morphometric evaluation of 2 different hydroxyapatite-bone derivatives in sinus augmentation procedures: a comparative study in humans.

BACKGROUND: Xenografts to augment the maxillary sinus have been used extensively. The aim of the present study was to evaluate, qualitatively and quantitatively, two different HA derivatives of natural and synthetic sources on newly formed bone in the augmented sinus. METHODS: A bilateral sinus augmentation procedure with simultaneous (16 out of 20 sites) or subsequent implant placement was performed in 10 patients. The antrum was randomly filled with a deproteinized, bovine hydroxyapatite mineral (B-HA) on one side and a non-ceramic resorbable hydroxyapatite (NC-HA) on the other. Cylindrical specimens were harvested from the augmented core at 12 months. Decalcified specimens were sectioned at a cross-horizontal plane and stained with hematoxylin and eosin for histopathologic and histomorphometric examinations. Tissue area fractions of bone, marrow, and the grafted particles were calculated for each specimen from the lateral to the deep region, and changes in values were compared within each material and between them. RESULTS: New bone formation was evident. B-HA and NC-HA particles were observed in all specimens surrounded by newly formed bone in direct connection or by soft tissue marrow. Morphometrically in the B-HA sites, from the lateral to deeper area, bone area fraction increased from 29.8% to 54.2% (average 42.1%) and marrow area fraction decreased from 37.9% to 26.7% (average 33.3%). The mineral area fraction decreased from 32.3% to 19.1% (average 24.7%). All increasing/decreasing patterns were statistically significant (P < 0.001). In the NC-HA sites, from the lateral to deeper area, bone area fraction increased from 25% to 36.5% (average 32.3%) and marrow area fraction decreased from 51.6% to 41.9% (average 43.2%) (P <0.001). The mineral area fraction decreased from 29% to 21.7% (average 24.6%) (P = 0.038). Comparison between the two HA derivative groups showed a significant difference between the bone area fraction averages (P = 0.0053) and between the increasing patterns along the core depth (P = 0.0006). There was also a significant difference between the decreasing marrow patterns (P = 0.003), but not between their averages. Comparison between the mineral area fractions showed no differences. CONCLUSIONS: B-HA and NC-HA were proven to be biocompatible materials. Although the B-HA-augmented sites showed a higher percentage of bone formation at 12 months, both are suitable bone derivatives in sinus augmentation procedures and can accommodate osseointegrated implants.

Efficacy of porous bovine bone mineral in various types of osseous deficiencies: clinical observations and literature review.

Recent developments in osseous regenerative techniques have increased the demand for bone-substitute grafting materials. Porous deproteinized bovine bone mineral (PBBM), a biocompatible xenograft, has been used in different osseous deficiencies prior to or in conjunction with the placement of titanium implants. The different PBBM applications in fresh extraction sites, anatomic defects, and subantral floor elevation techniques are described. The use of an occlusive barrier membrane to regenerate bone via guided tissue regeneration principles was determined for each patient by clinical parameters. PBBM was well amalgamated and incorporated with the augmented hard tissue, but the transition between preexisting bone and the newly regenerated bone-like tissue was distinguishable by clinical examination even after 12 months. Grafted material was also identified using follow-up radiographs. In the presented cases, PBBM showed clinically satisfactory results as a biocompatible filler in bone augmentation procedures.

Spontaneous early exposure of submerged endosseous implants resulting in crestal bone loss: a clinical evaluation between stage I and stage II surgery.

Spontaneous early exposure of submerged implants during the osseointegration healing phase may be a harmful factor that results in early crestal bone loss around the implants. The objective of this study was to assess the effect of spontaneous early exposure on crestal bone loss around submerged implants, with special attention given to the relationship between the degree of exposure and the amount of peri-implant bone loss. Crestal bone level relative to the shoulder of the implant was measured at the time of placement and at the time of exposure 4 to 5 months later. During the period between stage I and stage II surgery, implant sites were observed, and each implant site in which spontaneous early exposure was detected was recorded. Perforations were classified according to the degree of implant exposure from Class 0 (no perforation) to Class IV (complete exposure). Measurements from 206 implants in 64 patients produced 85 groups valid for statistical comparison; each of these contained at least 2 lesions of different types. There was a statistically significant difference between bone loss associated with intact mucosa (Class 0) and Class I, Class II, and Class III lesions, and between Class I and II lesions. There were no significant differences between Class I and III and between Class II and III. In Class II and III lesions, there was more bone loss associated with the buccal aspect of the implants. Of the 115 perforated sites, 10 were associated with bone loss exceeding 2 mm, 2 presented 3 to 4 mm bone loss, 1 showed more than 4 mm, and 1 displayed more than 5 mm. In view of the clinical implications that spontaneous early exposure may have on the success of osseointegration, prematurely partially exposed implants should be exposed as soon as possible after the perforation is observed.

Interproximal papilla augmentation procedure: a novel surgical approach and clinical evaluation of 10 consecutive procedures.

Periodontal plastic surgery enables enhanced esthetics in the anterior maxillary region. Reconstruction of the interdental papilla is one of the most challenging and least predictable of treatments. Several surgical and nonsurgical procedures to rebuild lost papillae have been presented; however, good results have been elusive. The purpose of the present study was to evaluate a novel surgical procedure based on an advanced papillary flap combined with a gingival graft intended to augment the soft tissue in the interdental area. The study comprised 10 consecutive papilla augmentation procedures performed in nine patients. Previous to the surgical procedure and at least 3 months postoperative, papilla contour measurements were carried out based on a papilla index score (PIS). PIS ranged from 0 to 2 preoperative (mean 1.0) and between 1 and 3 postoperative (mean 2.2). In eight procedures, PIS increased. Differences between pre- and postoperative PIS ranged from 0 to 3 PIS units (mean 1.2). Among the 10 procedures, there was an increase of 1 PIS unit in five, an increase of 2 PIS units in two, 3 PIS units in one, and no increase in the remaining two. This procedure is relatively easy to perform and offers a reliable solution to an esthetic problem. However, larger clinical and histologic follow-up studies are necessary before its long-term predictability can be established.

Tetracycline modulates collagen membrane degradation in vitro.

BACKGROUND: Structural integrity of implanted bioabsorbable barrier membranes should be preserved for a sufficient time to ensure expected results. Collagen membranes are degraded by metalloproteinases (MMP). Their degradation rate can be altered either by enhancing structural integrity or by delaying the degradation process using MMP inhibitors. Tetracyclines (TTC) present inhibitory effects on matrix MMP. Immersing membranes in TTC solution before implantation can delay their degradation. The purpose of the present study was to evaluate the effect of collagen membranes immersed in varying TTC concentration solutions on the rate of their degradation in vitro. METHODS: Collagen bioabsorbable membranes were prepared as 5 mm diameter membrane discs. Membranes were then incubated at 4 degrees C for 24 hours, in either phosphate buffered saline (PBS, Ca2+ and Mg2+ free) or with TTC-HCl dissolved in PBS concentrations of 5 mg/ml, 50 mg/ml or 100 mg/ml. After rinsing, membranes were incubated with either bacterial collagenase or cultures of human bone lineage cells. Membrane degradation was studied on days 2, 4, 7, and 14. Two- and 3-way analysis of variance was used to analyze results. RESULTS: Samples supplemented with bacterial collagenase exhibited a statistically significant interaction between changes of free protein in the medium, antibiotic concentration used for the immersion, presence of collagenase in the medium, and incubation time (P<0.0001). Membranes incubated with bone cells exhibited similar degradation trends. CONCLUSIONS: Collagen membranes immersed in 50 mg/ml TTC solution exhibited the longest degradation time, both in the clostridial collagenase and the human bone cell lineage assays. Immersion in a 50 mg/ml TTC solution before implantation will delay their degradation.

Healing of dehiscence defects at delayed-immediate implant sites primarily closed by a rotated palatal flap following extraction.

In 21 patients, 28 maxillary teeth were extracted because of periapical or periodontal infection, root fracture, or untreatable caries. A rotated palatal flap procedure was used to achieve primary soft tissue closure over extraction sites. At 5 to 7 weeks postextraction, 28 implants were placed. Buccal dehiscence-type defects were treated with guided bone regeneration procedures using bovine bone mineral and resorbable collagen membranes. Mean defect area at the time of implant placement (23.7 mm2, SD 11.49) was significantly reduced at uncovering (0.7 mm2, SD 0.99). The mean percentage of defect reduction (clinical bone fill) was 97% (SD 4.26). Implants placed in compromised sites shortly postextraction according to the presented 2-stage protocol gave good short-term clinical results.

Interproximal papillae reconstruction in maxillary implants.

BACKGROUND: Gingival esthetics has become an important factor in the overall success of most maxillary implant-supported restorations. Periodontal plastic surgery procedures may be used to enhance esthetics in the maxillary anterior region. The purpose of the present study was to evaluate a new surgical approach, performed at implant exposure, to reconstruct interdental papillae around maxillary implant-supported restorations. METHODS: The surgical procedure was performed on 32 patients, in which 36 consecutive single tooth osseointegrated implants were exposed in the anterior and premolar maxillary region. Previous to implant exposure and 6 months postoperatively, once the implant-supported restoration was in place, mesial and distal papilla contour measurements were calculated, based on a modification of the papillary index score (PIS). Statistical analysis consisted of paired t test, Pearson's correlation, and ANOVA with repeated measures. RESULTS: Preoperative PIS ranged from 0 to 3 and from 1 to 3 at the 6 months follow-up control. A mean of mesial and distal papilla, within the same tooth, was used for paired t test statistical analysis. A mean increase of 1.07 (SD 0.43) in PIS was statistically significant (P<0.001). At the second measurement, in no site was PIS smaller (0%) while in 64 sites PIS was higher (89%). In 51 papilla (71%) there was an increase of 1 PIS unit and 13 (18%) of 2 PIS units between both measurements. CONCLUSIONS: The presented surgical technique performed at second stage implant surgery was useful for partial or total interproximal papilla reconstruction adjacent to maxillary single-implant restorations.