D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology

The vertical bone increase of alveolar rim is important to obtain good results in rehabilitation with prostheses on implants. This Literature Review sought articles that treat bone increases of alveolar edges using Cytoplast® membranes, seeking to evaluate the resistance to bacterial penetration and capacity to create and maintain space. For this, a literature review was made on the Pubmed and Google scholar search platforms. The researches analyzed found similar results between d-PTFE membrane, titanium meshes and e-PTFE membranes, both in bone gain and bone quality. The space maintenance capacity was evident in the articles in which the titanium reinforced membrane was used. The d-PTFE membrane presented a greater capacity of exposure to the oral environment without compromising the graft material. The authors researched in this study found that titanium-reinforced d-PTFE membranes for bone augamble alveolar rim increases are viable and allow a certain period of exposure to the oral environment without graft contamination. Further studies are needed with the Cytoplast® d-PTFE membrane to explore its characteristics with vertical bone augmentation procedures.


INTRODUCTION
Implantodontics revolutionized dentistry, enabling the restoration of the absence of the dental organ, artificially. Often, the Implantodontist, when planning rehabilitation with implants, is faced with little height or width of the remaining alveolar rim, making it impossible to optimally position the implants according to the retrograde planning performed and to continue the planning can use the guided bone regeneration technique (ROG) to obtain a bone increase in the region that will receive the implants.
The 4 biological principles necessary for success in guided bone regeneration (i.e., PAEE) are: "(i) primary wound closure; (ii) angiogenesis to provide necessary blood supply; (iii) creation and maintenance of space and (iv) wound stability" (WANG; BOYAPATI, 2006, p. 8-11) Urban et al. (2016) described the flap technique where there is release of periosteum made with periosome and radial incisions and flap advancement with jerks in the coronal direction significantly increasing the surface of the flap, allowing filling with biomaterial and obtaining the primary closure of the wound. space.
3. LITERATURE REVIEW Barber et al. (2007) reported two cases of ROG with simultaneous implant installation and d-PTFE membrane covering  Biomedical, Lubbock, TX) without reinforcement. He reported an ROG technique where he left the membrane exposed without exposing the edges for 6 weeks in a case of extraction and immediate implantation of the upper 1st premolar. In the second case report, a trauma accident maintained the Cytoplast membrane® for 4 weeks, easily removing and obtaining a consistent layer of ostoid tissue in the placement of implants in an anterior maxillary region 5 elements without complications and epithelial migration occurred on the ostoid tissue at week 6, increasing the width of keratinized tissue before the injury suffered. Barber et al. (2007) pointed out that "the density of the d-PTFE membrane prevents the colonization of the host flora and prevents contamination of the biomaterial below the membrane". He also noticed that with this technique the keratinized mucosa heals by second intention, ending its closure with a larger area. Concluded that as the primary closure on the d-PTFE membrane is not necessary, the surgeon can treat large defects, preserve the interdental papilla and preserve the entire width of the keratinized mucosa, without the concern of contamination or bacterial infection and also that the use of Cytoplast® d-PTFE membrane is the ideal treatment option for alveolos of exodontias without primary closure of the wound , due to the simplicity in its placement and removal without compromising the quality of regeneration. (BARBER et al., 2007) Hoffmann et al. (2008 investigated the clinical regeneration of alveolos of exodontia, using d-PTFE membranes, without the use of graft material, for this purpose, evaluated 276 alveolos of exodontias in 276 individuals (151 men and 125 women; mean age, 50.2 years; age: 24 to 73 years). The percentage of bone gain obtained after ROG using Cytoplast® membrane, without the use of primary wound closure. Before extraction he made a personalized guide that could be fixed to adjacent teeth with five holes where through periodontal probe could obtain measurements of depth of the alveolo after extraction. After extraction, the flaps were elevated and a d-PTFE membrane  without titanium reinforcement was placed on the local extraction. The flaps were D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology www.nucleodoconhecimento.com.br repositioned and sutured in place. Primary closure was not obtained on the membranes. The membranes were removed after 4 months. The cemento-enamel junctions of adjacent teeth were used as reference points. The measurements were performed using the guide, after extraction and 12 months after surgery in the same areas, the variables described at the bone level were reported individually for all cases reviewed and also in the groups by factors of interest investigated: single alveolo or side by side, mandible, and region, bone gain in vertical defects were expressed in medium and still performed 10 biopsies of hard tissues 12 between the percentages of bone gain of the two groups. The two biopsies collected in the membrane removal procedure showed two regions: "one of well-organized lamellar bone and another with small gaps hosting osteocytes and a coronal part characterized mainly by bone tissue composed of small and immature trabeculae." (RONDA et al., 2014, p. 863). They concluded that, the d-PTFE and e-PTFE membranes showed identical clinical results in the treatment of vertical bone defects around the implants, using this technique and that the membrane removal procedure was easier to be performed in the d-PTFE group than that in the e-PTFE group, attributed to the porosities of the outer layer that adhere to the connective tissue, Ronda et al., (2014) emphasized that "although the presence of a porous portion of one of the membranes seems to play an important role in stabilizing the device , favoring its integration with the soft tissue, did not seem to be essential in obtaining bone regeneration. " Maridati et al., (2016) proposed and tested the management of d-PTFE Cytoplast® membrane exposures to achieve final clinical success, reported a case, in a procedure of vertical bone augmentation of alveolar rim, a 63-year-old patient where he installed a 3.4Ø x 11 mm implant, leaving some turns and the smooth side of the implant exposed, filled with Biooss® and adapted the membrane reinforced with Cytoplast® titanium fixing with 4 pins , accompanied an exposure of the d-PTFE membrane, even though it closed the wound without D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology www.nucleodoconhecimento.com.br tension. There was >3 mm with no sign of infection on the 14th day. The membrane was left in place for another two weeks. In the 4th week the membrane was removed and positioned a palate connective graft to protect the bone graft in the 7th month, the abutman and crown were successfully screwed. Based on the time that due to the Cytoplast membrane having high density and pores smaller than 0,2-0,3 micrometers and having already been tested in alveolos after exodontia before, without primary closure of the wound without tension, in this study obtained good results following the exposure of the membrane > 3 mm and subsequently grafting connective tissue when removing the membrane. They concluded that monitoring the exposure of the membrane without removing it for 4 weeks ensures the maintenance of appropriate space due to the membrane's resistance to bacterial contamination. Ghensi et al. (2017) demonstrated that it is possible to handle exposures of the Cytoplast® d-PTFE in their case report, followed < 3 mm exposure of d-PTFE membrane reinforced with autogenous graft and BioOss® 1:1 More tent screw, the primary closure of the wound with release of periosteum without tension was obtained, after 14 days the membrane was exposed, however, there was evidence of an epithelial seal at the site involved, without detaching to probing or suppuration. The problem was solved by continuing mouthwashes with chlorhexidine (0.12%), applying chlorhexidine gel with a concentration of 1% twice a day until the reopening procedure and removing any plaque once a week in the office where it followed for 4 months until removal, resulting in the filling of the Vertical defect of the premolar exodontics region and first upper molar. When the site was reopened, the original defect appeared to have been filled, then two implants (CLC Conic; CLC Scientific, Vicenza, Italy), respectively of size 4 × 10 mm and 5 × 6 mm, were inserted in the positions of the first premolar and molar position. They observed that because non-absorbable d-PTFE membranes present pores 0.2 μm in diameter, prevent bacterial infiltration, and even if the membrane is exposed, the risk of complications and infections is much lower than in e-PTFE membranes. This makes primary soft tissue closure important, but is not strictly necessary, because the membrane functions as an impenetrable barrier to food and bacteria and concluded that d-PTFE membrane exposure can be managed with a deep knowledge of the materials involved and adequate oral hygiene. between "surgical" and "healing" and between "minor" or "major". Primary implant stability and vertical bone gain were also evaluated. Obtained as results: In group A, the rates of surgical complications, in these cases, temporary paresthesia of the mentual nerve and healing were 5.0% and 15.0%, respectively, In group B, the rates of surgical and healing complications were 15.8% and 21.1%, respectively, were followed for 9 months until removal of the membranes. Bone gain was measured with periodontal probe with divisions of 1 mm and degree of accuracy of measurement of 0.5 mm that were measured from the shoulder of the implant to the bone, before filling with biomaterial by oral, lingual, mesial and distal, in each implant and after regeneration, new measurements were made. And they concluded that the preliminary results of this randomized controlled study showed that d-PTFE membranes and titanium meshes covered by collagen membrane produced similar results both in rate and in types in terms of healing complications. In contrast, d-PTFE membranes showed a lower average rate of surgical complications. Similar vertical bone gain and bone formation were achieved in both groups.
Herzberg (2017)  bone, Virginia Beach, VA, around the exposed turns 3-4.5 mm from the buccal side and then completed with a layer of BioOss®, and after that fixed the d-PTFE membrane with ProFix® mini screws. After 21 days the suture was removed and there was an exposure of 3 mm of the membrane, the patient was instructed to pass povidone-iodine twice a day with a cotton wool, the exposure continued to increase, evolving to severe dehiscence in the 16th week, but the edges of the membrane were not exposed, there was no evidence of infection, the membrane was removed revealing fibrous tissue covering the implants. 10 weeks after the membrane was removed, it was reopened and there was regenerated bone covering the cover screws. A core was removed with trephine for histological analysis and hematoxylin / eosin staining slides were prepared, and revealed a viable bone dense and around the bone the integrated allo-fill material. They concluded that the Cytoplast® membrane, when analyses revealed that a quantity of bacteria was present in the inner layer, below the perialveolar gingival tissues. This finding suggested that bacteria could migrate through the gums adhered to the membrane and colonize the inner part of the membrane, finding a path between the outer layer and gingival tissues that did not adhere to the smooth surface of the d-PTFE membrane. Another possibility is that colonization occurs during surgical procedures: however, in both circumstances, this did not affect the healing process, probably due to the small number of bacteria present at the site.
4. DISCUSSION Barber et al., (2007) and Ghensi et al., (2017) reported cases of ROG of exodontic alveolos that received biomaterial and the d-PTFE Cytoplast® membrane was used as a barrier. Barber et al. (2007), did not intentionally obtain the primary closure of the wound, which was described by WANG et al. in 2006 as a principle of PASS, claiming to be unnecessary due to the density of the d-PTFE membrane preventing contamination of the biomaterial below the membrane and kept for 6 weeks the membrane exposed to the oral environment with hygiene monitoring and concluded that the primary closure of the wound is unnecessary in his discussion he commented that he and his team did not have enough experience to comment on the effectiveness of keeping the membrane exposed for more than 6 weeks. Ghensi et al., (2017) exactly 10 years later, in his report, despite having double suture and initially obtaining primary wound closure, he reported an exposure of the membrane where he followed for 4 months. Both were successful with ROG, confirming that there was no graft contamination. And Ibraheem et al., (2020) observed a vertical increase exposure for 4 months, and obtained ROG, in this case report the Cytoplast Ti-250 membrane was fixed with screws. Koidou et al. (2019) in his case series obtained ROG, using Cytoplast® membrane and a collagen membrane between the graft and membrane, leaving the membrane intentionally exposed. Hertzberg (2017) in his case series obtained ROG using the Cytoplast Ti-250 membrane and a collagen membrane over the d-PTFE membrane that was fixed with D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology www.nucleodoconhecimento.com.br titanium pins and primary wound closure was obtained. Hassan et al., (2017) a randomized comparative study model of split mouth was used that decreases bias because it is possible to minimize the interindividual variables, since the participants serve as their own controls and, when present, interfere equally in the treatments. The membranes were Cytoplast® and MAC, ROG was kept maintaining membranes exposed to the oral environment for 3.5 months despite not having obtained as a primary result that the Cytoplast® membrane resisted bacterial penetration mentioned in its conclusion that the MAC exposed intentionally is equally effective in the preservation of the crest compared to d-PTFE and Hoffmann et al., (2008) in its longitudinal retrospective study, ROG performed on 276 alveolos of exodontias, which due to the relatively high population enrolled, reproduces a strong temporal relationship of chance. Some details of the study deserve to be highlighted: first the masking and calibration of the examiner who measured the defects and then the regeneration, and standardized the measurements with individual casquetes allowing 5 measurements mapping each defect, which increases the reliability of the results. When analyzing the data, the variables describing bone loss were reported individually by all cases involved and also separately in arms by investigated factors of interest that were: alveolo format, upper or lower maxillary and region and vertical bone gain was expressed in means ± (DP) and minimum, maximum and mean values. And independent test samples were used to detect some effect related to sex or smoking on bone loss and used Pearson's correlation to investigate age influence on bone gain. It found no influence of the variables mentioned above. He measured three-dimensional bone gain, obtaining an average vertical bone gain of 6 mm, and also collected samples that demonstrated that there was bone regeneration in histological analysis. In the description of the technique he emphasized that the primary closure of the wound was not obtained, the removal of the membrane was done after 4 months, both authors kept the exposed membranes including MAC for a period between 3.5 and 4 months.
Two experiments have raised relevant evidence on the characteristics of impermeability and integration capacity to Cytoplast® membrane tissues. Trobos et al., (2018) when testing the d-PTFE membrane in its in-vitro experiment with S.oralis culture 2,12,24 and 48hs, concluded that it is impervious to bacteria already Mazzucchi, et al., (2020) analyzed membranes taken from living patients and found bacteria at the bottom of the membrane in small amounts but did not harm the grafts, she argued that they could have penetrated the edges due to poor D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology www.nucleodoconhecimento.com.br tissue integration or during surgery. Gallo et al. (2019) when analyzing the complications in his study of 80 cases, he reported cytoplast membrane exposures®, which followed for 9 months guiding and accompanying patients regarding hygiene and the use of chlorhexidine 0.2% until cure. Proposing a protocol for the management of d-PTFE membrane exposures to the oral environment, it confirmed the resistance to bacterial penetration, corroborating the results and recommendations of Ibraheem et al., (2020). Ibraheem (2020) in his case report made a ROG in a region of 3 elements, and followed an exposure >3 mm for 10 months and concluded that the Cytoplast® membrane, when exposed, does not necessarily lead to failure if handled appropriately with short follow-up intervals, which confirms that the Cytoplast® d-PTFE membrane resists bacterial penetration corroborating Maridati, et al. , (2016) who had membrane exposure and followed for 4 months and when removing the membrane, also obtained ROG, the latter author did not mention the use of antiseptic but the use of a topical antiseptic seems to play an important role in the prognosis of exposures for Gallo (2019) and Ibraheem (2020). Urban et al., (2014) Oliveira (2015) in his article on Reports and case series noted that despite their importance, reports and series of cases are at risk of bias and that they usually publish success cases.
Because they had a low risk of bias, the following randomized trials: Ronda (2013) and Cucchi (2017) were selected to be grouped into a "Forest Plot" chart. Iportante emphasizes that, in so that they could have been published in the journal Clínical Oral Implant Research, as a consultation conducted on the journal's submission page, the excerpt follows: "Randomized clinical trials should be reported using CONSORT guidelines. A CONSORT 2010 checklist should also be included in the submission material" (AUTHOR GUIDELINES: 15/09/2020), so once they meet randomized testing guidelines, having met the requirements of the checklist, they can be considered gold standard. They were grouped in a "Forest plot" obtained with the use of the Review Manager 5.4 software that could be performed due to the low heterogeneity between the studies and quantitative results of bone gain in mm, which could be observed by the x² and I² test presented in the subtitles with results 0.55 and 0% respectively, which suggested that the fixed effect analysis model should be used. It only confirms the authors' conclusions, but demonstrates a pattern tending to favor the Cytoplast membrane® in relation to titanium screen and e-PTFE membrane in bone gain / is understood as capacity for creating and maintaining space also due to the graft relying completely on the membrane to remain position, for example if the studies had twice the D-Ptfe Cytoplast® membranes in guided bone regeneration in implantology www.nucleodoconhecimento.com.br total of interventions would already move the black rando out of axis 0, which also proposes to carry out studies such as these with a minimum sampling of two times higher. Review Manager 5.4 software was used to set meta-analysis and simulations. The way Review Manager 5.4 performed the calculations was described by Deeks and Higgins, (2010). The types of data found in the results of randomized clinical trials were continuous, the analysis method chosen was fixed-effect inverse variance and the effect measurement in standard mean difference and 95% confidence intervals.
Analyzing the reports and case series where they chose to try to leave the membrane intentionally exposed, based on the characteristic of impermeability to bacteria and integration of tissues to the membrane and which obtained bone regeneration and bone gain both in height and width and still some proved by histological and histomorphometric analyses, there was still a gap on the quality of the integration of the Cytoplast® d-PTFE membrane to the tissues, if it is complete enough to prevent the flap of the mucosa from allowing the passage of bacteria in cases of exposure, the use of chlorhexidine in topical gel and mechanical removal of plaque in the upper part of the membrane are essential in the control of exposures and periodontal control prior to and after surgical intervention are practices that can minimize this risk. It was observed that there is evidence and that it requires models of studies with this membrane that explore these properties.

CONCLUSION
After analyzing the scientific work of this review, we conclude that the Cytoplast® d-PTFE membrane meets the needs of a membrane for preservation and increase of alveolar rim, allowing a period of exposure to the oral cavity, without infiltration of microorganisms in the grafted region provided that the patient is accompanied by a rigid hygiene protocol and the edges of the membrane are covered by tissue and in cases of vertical augmentation when reinforced with titanium and fixed by studs screws, Cytoplast Ti-250 is able to create and maintain space so that there is ROG when obtained closure of the primary wound without tension done with periosteum release incision maneuver.