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Introduction: The aim of this systematic review was to analyse current evidence regarding differences in early and late implant failure as well as in marginal bone level (MBL) changes between submerged and non-submerged healed dental implants., Methods: PUBMED, SCOPUS, EMBASE and Web of Science databases were searched for prospective randomized and non-randomized controlled studies addressing direct comparison between submerged and non-submerged implant healing, without performing immediate loading. Early and late implant failure (before or after 6 months from implant placement, respectively) together with MBL were the investigated outcomes. Risk of bias assessment was performed using the Cochrane Collaboration Tool for Randomized clinical trials. Meta-analysis was performed and the power of the meta-analytic findings determined by trial sequential analysis (TSA)., Results: Eleven studies met the inclusion criteria and were included in the review. Results of this systematic review revealed a small higher rate (2%) of early implant failure when a non-submerged healing approach is performed. Late implant failure appears not to be different in submerged or non-submerged healing, but the power of evidence, as determined by TSA, is not high. If we consider MBL changes at 1 year from implant load, it seems that non-submerged healing may better preserve marginal bone, although with a small effect size (0.13 mm)., Conclusions: Implants placed with a non-submerged technique have a higher risk (2%) of early failure. The power of the evidence about the effects on MBL is low, but present results seem to favour non-submerged healing, although with a very small effect size., (© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To study the early sequential stages of osseointegration at implants installed in alveolar bony., Materials and Methods: In 12 Labrador dogs, all mandibular premolars and first molars were extracted bilaterally. After 3 months of healing, full-thickness flaps were elevated in the edentulous region of the right side of the mandible. Implants were installed, and the flaps were sutured to allow a fully submerged healing. The timing of the installations in the left side of the mandible and of sacrifices were performed with a schedule that various observation periods to sacrifice from 5, 10, 20, and 30 days were available so that n = 6 was obtained per each healing period. Ground sections were prepared and analyzed., Results: Newly formed bone in contact with the implant surface was found after 10 days of healing and the percentage increased up to 50% after 1 month of healing. A higher percentage was found in the trabecular compared with the cortical bony compartment. Old bone decreased by about 50% during healing, being still present after 1 month (16%). The proportions of bone debris and bone particles were at 27% after 5 days and decreased during healing to 6% after 1 month., Conclusion: Osseointegration (new bone-to-implant contact) developed at various rates for cortical and trabecular compartments, respectively. In the trabecular region, mesenchymal cells were identified, subsequently developing into new bone in contact with the implant surface. In the cortical compartment, however, resorptive processes were observed throughout all periods of healing. The proportion of newly formed bone percentage was lower compared with that of the trabecular area. Old bone was still present after 1 month of healing in both compartments. Bone debris and small bone particles appeared to be involved in initial bone formation., (© 2013 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.)

Aim: To investigate whether transmucosal healing is as effective as submerged healing in terms of buccal bone regeneration when guided bone regeneration (GBR) is performed simultaneously with implant placement. Materials and Methods: In six dogs, buccal dehiscence defects were created in the edentulous mandibular ridge, sized 5 × 5 × 3 mm (length × height × depth). In each defect, a bone‐level implant was placed, and four experimental groups were randomly assigned as follows: (i) transmucosal healing with GBR (T‐GBR), (ii) transmucosal healing without GBR (T‐control), (iii) submerged healing with GBR (S‐GBR) and (iv) submerged healing without GBR (S‐control). Data analyses were based on histological slides 5 months after implant placement. Results: The T‐GBR group showed significant differences compared to the control groups regarding defect height resolution, buccal bone thickness and mineralized tissue area (p <.05), but showed no significant differences when compared with the S‐GBR group (p >.05). Conclusions: The mode of healing (transmucosal vs. submerged) does not influence bone regeneration at implant sites. The clinician may therefore choose the approach based on further clinical and patient‐specific parameters. [ABSTRACT FROM AUTHOR]

Purpose: This pilot study evaluated the wound healing and tissue response after placement of two different skin substitutes in subgingival mucosal pouches in rabbits. Materials and Methods: Four rabbits were selected to receive a commercially available skin substitute consisting of a collagen matrix with fibroblasts and an epithelial layer (test membrane 1) and a prototype device consisting of a collagen matrix with fibroblasts only (test membrane 2). In each rabbit, two horizontal incisions were made in the buccal alveolar mucosa of the maxilla bilaterally to create submucosal pouches. Three pouches in each animal were filled with either the test 1 or test 2 membranes, and one pouch was left without a membrane (sham-operated control). All rabbits were sacrificed after a healing period of 4 weeks, and histologic samples were prepared and examined. Results: After a healing period of 1 month, both tested membranes were still visible in the sections. Test membrane 1 was still bilayered, contained inflammatory cells in its center, and was encapsulated by a thick fibrous tissue. Numerous ectopic calcifications were evident in the collagenous part of the membrane and in association with some basal epithelial cells. Test membrane 2 was also encapsulated in fibrous tissue, with inflammatory cells present only between the fibrous encapsulation and the remnants of the membrane. For test membrane 2, no calcifications were visible. Conclusions: Test membrane 1 seemed to be more resistant to degradation, but there was also a more pronounced inflammatory reaction in comparison to test membrane 2, especially in the vicinity of the keratinocytes. The significance of the ectopic calcifications, along with that of the resorption or degradation processes of both tested membranes, must be evaluated in future experimental studies, with different time points after implantation examined. [ABSTRACT FROM AUTHOR]

Objective To study the early sequential stages of tissue composition in the cortical and marrow compartments of the alveolar bone crest at implants with a moderately rough surface. Materials and methods Three month after tooth extraction in 12 Labrador dogs, full-thickness flaps were elevated in the edentulous region of the right side of the mandible and one implant was installed. The flaps were sutured to allow a fully submerged healing. The timing of the installations in the left side of the mandible and of sacrifices were scheduled in such a way to obtained biopsies representing the healing after 5, 10, 20, and 30 days. Ground sections ( n = 6 per each healing period) were prepared, and the percentages of osteoid/new bone, old bone, new soft tissues (provisional matrix and primitive marrow), mature bone marrow, vessels, and other tissues (bone debris/particles and clot) were evaluated laterally to the implant surface up to a distance of about 0.4 mm from it. Results Osteoid/new bone was found after 5 days at percentages of 10.8 ± 4.3% at the marrow and 0.6 ± 0.6% at the cortical compartments. After 30 days, these percentages increased up to 56.4 ± 4.0% and 23.3 ± 6.1%, respectively. Old parent bone was resorbed between 5 and 30 days from 28.7 ± 10.9% to 14.9 ± 3.4% at the marrow (~48% of resorption) and from 81.2 ± 9.4% to 67.6 ± 5.6% at the cortical (~17% of resorption) compartments. All differences were statistically significant. Conclusion Bone apposition to an implant surface followed a significantly different pattern in the compact and the marrow compartments around the implants. While in the compact compartments, bone apposition had to develop through the BMUs following resorption, it developed in very dense layers through an early apposition in the marrow compartments. [ABSTRACT FROM AUTHOR]

Aim: The temporal pattern of bone-level alterations in conventionally restored implants is dependent upon healing mode (open or submerged). This study examined the influence of healing on marginal bone levels at implants with a medium-rough surface including the implant collar and a clearance-fit implant-abutment connection restored according to a platform-switching concept. Material and Methods: Two implants were placed in the posterior mandible of 21 test subjects, randomly assigned to open (OH) or submerged (SH) healing. Standardized radiographs were obtained after implant surgery, before re-entry, after crown mounting, 1 and 2 years after implant surgery, and evaluated for implant-bone-level alterations (ΔIBL). Bacterial samples of the implants' inner cavities were analysed by cultivation. Statistics: Brunner-Langer Model, equivalence testings by Wilcoxon's (equivalence range ± 0.4 mm). Results: After 2 years, ΔIBL were -- 0.47 ± 0.46mm (OH) and --0.54 ± 0.38mm (SH). At the 1-year follow-up, all implants were contaminated with bacteria. ΔIBL (p < 0.001) and the amount of bacterial contamination (p < 0.001) significantly depended on time, but not on healing mode. ΔIBL of OH and SH were equivalent at all time points (all p ≤ 0.044). Conclusions: Platform-switched implants showed very limited peri-implant bone-level alterations. The healing-mode neither affected the total amount nor the temporal patterns of ΔIBL. Thus, the results for the tested implants with a non-rigid implant--abutment connection were similar to results reported previously for implants with a rigid implant-abutment connection. [ABSTRACT FROM AUTHOR]

Soft and hard tissue healing around submerged and nonsubmerged versions of one dental implant design was evaluated in an experimental canine peri-implantitis model. Forty-eight c.p. Ti-implants with integrated (one-piece=OPI) or screw-on (two-piece=TPI) abutments were inserted in edentulous mandibles of eight beagle dogs, one OPI and one TPI with connected abutments for nonsubmerged and one TPI without abutment (SMI) for submerged healing. After 3 months, all implants were functionally loaded, and at 4 months peri-implantitis was ligature-induced in one jaw side. Intravital polyfluorochrome labeling, monthly conventional radiography and gingival probing of all 48 implants were performed until sacrifice 8 months postimplantation. Undecalcified ground sections in the bucco-lingual and mesio-distal planes of four dogs (23 implants, one implant lost) were evaluated by light and fluorescence microscopy. The immunohistochemical and SEM-vascular corrosion cast results of the four other dogs (24 implants) will be reported elsewhere. Levels of alveolar bone-to-implant contact (ABICL), alveolar crest (ACL) and junctional epithelium-to-implant contact were determined by computer-assisted histometry. Peri-implant alveolar bone loss (=saucerization) was assessed on the radiographs and calculated as ACL minus ABICL from histometric data. Around SMIs and OPIs without ligature less plaque adhesion and lower gingival indices were found when compared to TPIs. Radiologically, all ligatured, but also some nonligatured implants showed alveolar bone loss. Histometry demonstrated reduced ABICL around all these implants. Saucerization was more pronounced on the lingual and mesio-distal sides. Particularly around TPIs, bone resorption was still active or bone formation was impaired on fluorochrome labeling. Only around SMIs and one OPI without ligature continuing alveolar bone formation reflected by gains in ABICL were found. The clinical and histometric results of this study demonstrate that healing of submerged SMIs was not impaired by the two-stage procedure, resulting in equally good healing as around nonsubmerged OPIs. However, peri-implantitis plaque-induced by ligature and/or dilated abutment connection microgaps in TPIs affected alveolar bone-to-implant contacts more than transmucosal or submerged healing mechanisms. To cite this article: Zechner W, Kneissl M, Kim S, Ulm C, Watzek G, Plenk H Jr. Histomorphometrical and clinical comparison of submerged and non-submerged implants subjected to experimental peri-implantitis in dogs. Clin. Oral Impl. Res. 15, 2004; 23–33 [ABSTRACT FROM AUTHOR]