The effect of experimental diabetes and membrane occlusiveness on guided bone regeneration: A proof of principle study

Clinical Oral Investigations - To evaluate the effect of membrane occlusiveness and experimental diabetes on early and late healing following guided bone regeneration. A total of 30 Wistar rats...     

Association between interleukin-6 promoter haplotypes and aggressive periodontitis

Background: Interleukin‐6 (IL‐6) polymorphisms have been shown to affect IL‐6 promoter activity. This study investigated the possible role of IL‐6 genetic polymorphisms and haplotypes in the predisposition to aggressive periodontitis (AgP). Material and Methods: A case–control association study on 224 AgP patients and 231 healthy controls was performed in order to detect differences in genotype distributions of five single nucleotide polymorphisms (SNPs) located in the promoter region of the IL‐6 gene. Results: The IL‐6 ?1363 polymorphism was associated with a diagnosis of AgP in subjects of all ethnicities (p=0.006, adjusted logistic regression). The ?1480 SNP was associated with LAgP in subjects of all ethnicities (p=0.003). The ?1480 and ?6106 polymorphisms were associated with Localized AgP in Caucasians (n=24) (p=0.007 and 0.010, respectively). Haplotypes determined by the ?1363 and ?1480 polymorphisms were also associated with LAgP (p=0.001) in Caucasians. Conclusions: This study supports the hypothesis of a link between IL‐6 genetic factors and AgP and highlights the importance of two IL‐6 polymorphisms (?1363 and ?1480) in modulating disease phenotype and susceptibility.     

Long-term stability of autogenous bone grafts following combined application with guided bone regeneration

The aim of the study was to compare the long-term stability of membranous and endochondral autogenous bone grafts with or without combined application of guided bone regeneration (GBR). Twenty-five, male, 6-month old, albino rats were used in the study. The animals were divided into four groups (A5, A11, B5 and B11). Group A5 (control): The inferior border of the mandible was exposed in both sides. At one side of the jaw, a calvarial bone graft (baseline -3 x 4 x 0.64 mm) was placed at the inferior border of the mandible and was fixed with a standardized screw-type titanium microimplant. At the contralateral side, an ischiac bone graft (baseline -3 x 4 x 0.87) was transplanted. The healing period was 5 months. Group A11 (control): The animals were treated in the same manner as in Group A5 with the difference that the healing period was 11 months. Group B5 (test): The animals were treated in the same manner as in Group A5 with the difference that an e-PTFE membrane was adapted over the bone graft on each side of the jaw. Group B11 (test): The animals were treated in the same manner as in Group B5 with the difference that 5 months following transplantation the animals were subjected to a second operation and the membranes were removed. The healing period was 11 months. The animals were killed at 5 (Groups A5 and B5) or at 11 months (Groups A11 and B11) following mandibular augmentation and the jaws were defleshed. The width, the length and the thickness/height of the bone graft were evaluated by means of a stereomicroscope. At 5 months, both types of the membrane-treated bone grafts presented increase in all dimensions compared with baseline. However at 11 months, both types of the membrane-treated bone grafts exhibited a decrease in their dimensions which were similar to the baseline measurements. In the control groups, both types of bone graft presented significant resorption both at 5 and at 11 months with the ischiac bone grafts presenting more resorption in width and length than the calvarial bone grafts. It can be concluded that the long-term volume stability of autogenous endochondral and membranous onlay bone grafts combined with GBR is superior to that of autogenous endochondral and membranous onlay bone grafts alone.     

Clinical and histologic evaluation of human intrabony defects treated with an enamel matrix protein derivative (Emdogain)

An enamel matrix protein derivative (Emdogain) has been recently shown to promote periodontal regeneration in experimentally created recession-type defects. However, only limited histologic data from human material are available concerning the healing of intrabony periodontal defects following treatment with Emdogain. The aim of the present study was therefore to present the clinical and histologic results following the application of Emdogain in intrabony defects. Two patients with marginal periodontitis and deep intrabony defects adjacent to teeth scheduled for extraction were treated with Emdogain. The postoperative healing phase was uneventful in both cases. At 6 months following treatment, newly formed cementum with inserting collagen fibers was found in both specimens. In one case, the new attachment formation was also accompanied by bone neoformation. The results of this human histologic study indicate that Emdogain possesses the potential to stimulate new connective tissue attachment formation in human intrabony defects.     

Five-year results following treatment of intrabony defects with enamel matrix proteins and guided tissue regeneration

BACKGROUND: Treatment with enamel matrix proteins (EMD) or guided tissue regeneration (GTR) has been shown to enhance periodontal regeneration. However, until now there are limited data on the long-term results following these treatment modalities. Aim: The aim of the present clinical study was to present the 5-year results following treatment of intrabony defects with EMD, GTR, combination of EMD and GTR, and open flap debridement (OFD). MATERIAL AND METHODS: Forty-two patients, each of whom displayed one intrabony defect of a probing depth of at least 6 mm, were randomly treated with one of the four treatment modalities. The following parameters were evaluated prior to surgery, at 1 year and at 5 years after: plaque index, gingival index, bleeding on probing, probing pocket depth (PPD), gingival recession, and clinical attachment level (CAL). No statistically significant differences in any of the parameters were observed at baseline between the four groups. RESULTS: The sites treated with EMD demonstrated a mean CAL gain of 3.4+/-1.1 mm (p<0.001) and of 2.9+/-1.6 mm (p<0.001) at 1 and 5 years, respectively. The sites treated with GTR showed a mean CAL gain of 3.2+/-0.8 (p<0.001) at 1 year and of 2.7+/-0.9 mm (p<0.001) at 5 years. The mean CAL gain at sites treated with EMD+GTR was 3.0+/-1.0 mm (p<0.001) and 2.6+/-0.7 mm (p<0.001) at 1 and 5 years, respectively. The sites treated with OFD demonstrated a mean CAL gain of 1.6+/-1.0 mm (p<0.001) at 1 year and 1.3+/-1.2 mm (p<0.001) at 5 years. At 1 year, the only statistically significant difference between the four different treatments was found in terms of PPD reduction and CAL gain between EMD and OFD (p<0.05). However, at 5 years there were no statistically significant differences in any of the investigated parameters between the four different treatments. CONCLUSION: Within the limits of the present study, it may be concluded that the short-term clinical results following treatment with EMD, GTR, EMD+GTR, and OFD can be maintained over a period of 5 years.     

Clinical outcomes of implants following lateral bone augmentation: systematic assessment of available options (barrier membranes, bone grafts, split osteotomy)

Objective: To compare the clinical outcomes related to implants following lateral augmentation procedures (GBR, bone grafts, split osteotomy) with implants placed in pristine sites.
Material and Methods: A systematic review of all prospective studies of implants placed simultaneously or as a second surgery following lateral augmentation compared with implants placed in pristine bone with 6 months of loading was performed.
Results: From 435 potentially relevant publications, 125 full-text publications were screened and four were identified as fulfilling the inclusion criteria. Three studies compared implants placed with simultaneous GBR or with a bone substitute and one with autogenous bone graft as a staged procedure. The implant survival at the augmented sites irrespective of the procedure used varied from 91.7% to 100% and from 93.2% to 100% at the control sites for a period between 12 and 59.1 months.
Conclusions: Within the limits of the systematic review there was evidence that the evaluated augmentation techniques result in similar implant survival between augmented and pristine sites. The small number of retrieved studies fulfilling the inclusion criteria limited the conclusions regarding the success of the augmentation and its effect on the survival of the implants. Properly designed randomized controlled clinical trials on this topic are needed.     

The effect of SLActive surface in guided bone formation in osteoporotic-like conditions

Objectives: The aim of the study was to evaluate new bone formation under etched titanium (SLA) and modified‐etched hydrophilic titanium (modSLA) domes placed on the calvarium of healthy, osteoporotic and osteoporotic treated with bisphosphonates rabbits. Methods: Experimental osteoporosis was induced by ovariectomy (OV) and calcium‐deficient diet in 24 New Zealand female rabbits. Twelve OV rabbits were treated with weekly dozes of alendronate (Fosamax^®) (B) while 12 OV rabbits received no treatment (O). Another 12 rabbits were sham operated and used as healthy controls (C). At 6 weeks following OV, one modSLA and one SLA titanium dome were placed in the parietal bones of each rabbit. The animals were sacrificed at 30 and 120 days following the dome placement. Various histomorphometric measurements were performed in the most central of the undecalcified sections produced. Results: After 30 days of healing, in the C group, the total bone (TB) area was 37.6% and 37.0% under the modSLA and SLA domes, respectively. In the O group, the TB was 35.7% and 24.8%. In the B group, TB was 37.0% and 32.1%, respectively. After 120 days of healing, in the C group TB was 40.1% and 36.4%, respectively. In the O group, TB was 29.6% and 27.9%, respectively. In the B group, TB was 49.7% and 42.5%, respectively. Hierarchical analysis of variance showed that the type of titanium dome significantly influenced new bone and the amount of new bone being in contact with inner surface of the dome (BIC) independently of the observation period and group (P<0.05). The administration of bisphosphonates influenced the BIC (P<0.05). Conclusion: The use of modSLA surface may promote bone healing and osseointegration in osteoporotic rabbits, whereas administration of bisphosphonates may compromise the osseointegration of the newly formed bone at the early healing period. To cite this article:
Mardas N, Schwarz F, Petrie A, Hakimi A‐R, Donos N. The effect of SLActive surface in guided bone formation in osteoporotic‐like conditions.
Clin. Oral Impl. Res. 22 , 2011; 406–415.
doi: 10.1111/j.1600‐0501.2010.02094.x     

Patterns of cytokeratin expression in monkey and human periodontium following regenerative and conventional periodontal surgery

The pattern of cytokeratin expression has been extensively described in the normal and inflamed periodontium. However, there is no information regarding the pattern of cytokeratin expression in the periodontium which has been reformed following regenerative periodontal surgery. The aim of the present investigation was to evaluate the pattern of cytokeratin expression in the reformed human and monkey periodontium following regenerative and conventional periodontal surgery. In 3 monkeys, acute fenestration-type and chronic intrabony defects were treated with guided tissue regeneration (GTR), enamel matrix proteins (EMD), or coronally repositioned flap surgery (control). After a healing period of 5 months, the animals were sacrificed and perfused with 10% buffered formalin for fixation. Specimens containing the defects and surrounding tissues were dissected free, decalcified in EDTA and embedded in paraffin. Histological sections were cut with the microtome set at 3 microm. The sections were alternatively stained either with hematoxylin and eosin, or immunohistochemically by using one of the broad range monoclonal antibodies 34betaE 12 (for cytokeratins 1, 5, 10 and 14) or KL 1 (for cytokeratins 1, 2, 5, 6, 7, 8, 10, 11, 16 and 19), or one of the individual monoclonal antibodies LL025 (for cytokeratin 16), DC 10 (for cytokeratin 18), A53-B/A2 (for cytokeratin 19). Twelve patients, each displaying one deep intrabony defect scheduled for extraction due to advanced periodontitis or prosthetic reasons, were treated as described above. Following a healing period of 6 months, the teeth were extracted together with some of their surrounding soft and hard tissues. The histological and immunohistochemical processing of the human biopsies was identical to that described in monkeys. The results revealed that both the normal non-treated (original) monkey and human junctional epithelium stained strongly with all of the monoclonal antibodies used. The reformed junctional epithelium displayed the same cytokeratin expression pattern as the non-treated junctional epithelium. No differences regarding the cytokeratin expression pattern of the junctional epithelium were found between the treatments and types of healing (i.e. regenerative, through a new periodontal ligament, or reparative through a long junctional epithelium). In the intact periodontal ligament, the epithelial rests of Malassez displayed a comparable cytokeratin expression pattern to that of the junctional epithelium. However, no expression of cytokeratins was seen in the newly formed periodontal ligament. In such specimens, cytokeratin expression was observed only until the borderline between the regenerated cementum and the epithelial downgrowth. It was concluded that: a) the reformed junctional epithelium, following any type of surgical procedure, displays a similar pattern of cytokeratin expression to the original junctional epithelium; b) in the newly formed periodontal ligament, no expression of cytokeratins is present; and c) the epithelial rests of Malassez do not seem to reform after regenerative periodontal surgery.     

In vivo gene expression profile of guided bone regeneration associated with a microrough titanium surface

Objectives: To determine the gene expression profile characteristic of “guided bone regeneration” associated with a microrough titanium surface. Material and methods: Critical‐size calvarial defects were treated with the principle of “guided bone regeneration,” whereby the extracranial barriers were either polished (SMO) or microrough (SLA) titanium disks. After 7 and 14 days, the contents of the regenerating defect were collected, RNA was extracted and microarray analysis was carried out. At each time point, the healing associated with the microrough surface was compared with that associated with the polished titanium surface. Results: On comparing the SLA and SMO profiles, there were few genes different at day 7 (～250), whereas there were a large number of genes different at day 14 (～6500). At day 14, the list of genes that were differentially regulated in response to the SMO and SLA surfaces had an over‐representation of genes associated with the functionally relevant gene ontology categories of regeneration, skeletogenesis, mesenchymal cell differentiation, angiogenesis and neurogenesis. There were a greater number of genes within each of these functionally relevant categories that were up‐regulated on the SLA surface compared with the SMO surface. The main signalling pathway that was differentially regulated between the two surfaces at day 14 was the Wnt signaling pathway. Conclusions: Minimal difference was observed between the SMO and the SLA samples at day 7, whereas significant differences were noted at day 14, including genes associated with a number of functionally relevant gene ontology groups. The differentially regulated biological processes provide an insight into the influence of surface topography on “guided bone regeneration” at the cellular and molecular level. To cite this article:
Donos N, Retzepi M, Wall I, Hamlet S, Ivanovski S. In vivo gene expression profile of guided bone regeneration associated with a microrough titanium surface.
Clin. Oral Impl. Res. 22 , 2011; 390–398.     

Comparison of enamel matrix proteins and bioabsorbable membranes in the treatment of intrabony periodontal defects. A split-mouth study

BACKGROUND: Enamel matrix proteins (EMP) have recently been introduced as a new modality for regenerative periodontal treatment. However, limited information is available concerning the comparison of the treatment of intrabony periodontal defects with enamel matrix proteins and other regenerative treatment alternatives. METHODS: The aim of the present controlled clinical trial was to compare the treatment of deep intrabony periodontal defects with EMP to that with guided tissue regeneration (GTR) with bioabsorbable membranes. Sixteen patients, each of whom displayed one pair of intrabony defects located contralaterally in the same jaw, were randomly treated with EMP or with a bioabsorbable membrane. Prior to surgery and 8 months later the following parameters were evaluated by a blinded examiner: Plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR), and clinical attachment level (CAL). Antibiotics (amoxicillin and metronidazole) were given during the first 10 days after surgery. No statistical significant differences in any of the investigated parameters between the 2 groups were observed at baseline. RESULTS: No serious adverse events (e.g., allergic reactions or abscesses) after any of the treatments were noted during the entire observation period. Membrane exposure occurred in 7 out of the 16 GTR treated sites. Clinical examination was performed again 8 months postoperatively. Sites treated with EMP demonstrated a reduction of PD from 8.1+/-1.7 mm to 4.3+/-1.2 mm (P <0.001) and a change in CAL from 10.3+/-1.8 mm to 7.2+/-1.2 mm (P <0.001). The sites treated with GTR showed a reduction of PD from 8.3+/-1.7 mm to 4.3+/-0.7 mm (P <0.001) and a change of CAL from 10.1+/-1.9 mm to 7.1+/-1.7 mm (P <0.001). Both treatment procedures led to significant improvements of PD and CAL. However, no statistically significant differences in any of the investigated parameters were observed between the test and control group. CONCLUSIONS: It may be concluded that both therapies led to shortterm improvements of the investigated clinical parameters. Further studies of much higher power are needed to support equivalence.