Critical-size Defect Augmentation Using Sintered and Non-Sintered Bovine Bone Matrix - An Experimental Controlled Study in Minipigs.

PURPOSE: Xenogeneic bone substitute materials are often used for augmentation of larger bone defects. Purification methods for these materials vary, mainly in terms of temperature. The aim of this study was to determine in vivo how sintering affects quantitative and qualitative bone regeneration of 2 bovine augmentation materials. METHODS: A total of 56 critical size defects were set at the frontal bone of 14 domestic pigs (4 each) and filled randomly with either bovine, sintered hydroxyapatite (BO), bovine, non-sintered hydroxyapatite (BOS), local autologous bone (AB) or left empty. All defects were additionally covered with a collagen membrane. Specimens were harvested after 4 and 8 weeks and were evaluated histologically and histomorphometrically. RESULTS: Histologically new bone could be seen in every group. Significantly highest new bone formation was found in AB. No significant difference could be detected between BO and BOS. CONCLUSIONS: According to the results of this study, sintered bone substitute material remains histologically distinguishable but does not affect quantitative and qualitative bone regeneration.

Influence of different carrier materials on biphasic calcium phosphate induced bone regeneration.

OBJECTIVES: Biphasic calcium phosphate (BCP) is a bioceramic material successfully used in alloplastic bone augmentation. Despite many advantages, a disadvantage of BCP seems to be a difficult application and position instability. The aim of this study was to determine how different carrier materials influence BCP-induced quantitative and qualitative bone regeneration. MATERIALS AND METHODS: A total of 70 critical size defects were set in the frontal bone of 14 domestic pigs (5 each) and filled randomly with either BCP alone (BCP), BCP in combination with nano-hydroxyapatite (BCP + NHA), BCP embedded in native porcine type I/III collagen blocks (BCP + C), autologous bone (AB), or were left empty (ED). Specimens were harvested after 4 and 8 weeks and were evaluated histologically as well as histomorphometrically. RESULTS: Significantly lowest rate of new bone formation was found in ED (p = < 0.001) and BCP + NHA groups (p = 0.05). After 8 weeks, the highest percentage of new bone formation was observed in the BCP + C group. Fibrous matrix was detected highest in BCP alone. The lowest residual bone substitute material was found in BCP + C after 8 weeks. CONCLUSIONS: BCP-induced bone regeneration is indeed affected by different carrier types. Surface morphology and bioactive characteristics influence osseointegration and new bone formation in vivo. The combination of type I/III collagen seems most suitable for qualitative and quantitative bone regeneration. CLINICAL RELEVANCE: Stabilization of granular bone substitutes using type I/III collagen might be an alternative to granulates alone, indicating excellent volume stability, satisfactory plasticity, and easy application.

Osteotomy speed, heat development, and bone structure influence by various piezoelectric systems-an in vitro study.

OBJECTIVES: The aim of this in vitro study was to evaluate osteotomy speed, heat development, and bone structure influence from osteotomies performed by various piezoelectric devices and insert tips. These devices and tips were compared among each other with regard to conventional rotatory and oscillating systems with special focus on the insert tip design and thickness. MATERIAL AND METHODS: The osteotomies were conducted on porcine ribs utilizing 12 different insert tips (straight and angulated) and three conventional systems. After time and temperature measurements, histological analysis was carried out. Light microscopy was used to evaluate the roughness of the osteotomic surface and to search for indications of thermal bone necrosis. A special software analyzing tool was employed to determine cutting width (mm) and debris (%). RESULTS: All piezoelectric tips created smooth cuts. Cutting widths in general were wider than the actual insert tip size with a tendency for narrow straight insert tips producing relatively wide osteotomies, whereas narrow angulated inserts produced relatively small osteotomies. None of the samples demonstrated distinct indication of necrosis. Overall, there was only a small amount of debris in all osteotomy gaps. Conventional rotatory saws were faster and created less heat compared to all tested piezoelectric systems. Straight tips proved faster osteotomy speed than angulated tips. Thin insert tips indicated to have a positive correlation to osteotomy time and performed faster than conventional microsaw. The average temperature rise was lower when using conventional systems, but critical exceeding temperatures were only observed in short-time exceptional cases. In general, temperature rise was less when using angulated inserts. CONCLUSION: All tested tips are appropriate for bone surgery. Only small differences were found among the piezoelectric insert tips. Although conventional rotatory systems in general performed faster osteotomies, special designed and thin piezoelectric insert tips seem to have a positive influence on osteotomy speed. Ultimately, none of the tested devices or inserts combined all best features of speed, heat development, bone structure influence, and safety. CLINICAL RELEVANCE: Narrow and straight piezoelectric insert tips demonstrated reduced osteotomy times. Nevertheless, a combination of conventional and piezoelectric systems in clinical practice might be the best way to work time-efficient, patient-oriented, and safe. The choice of instrument should be based on clinical experience of the user and should be evaluated individually depending on the case.

Monophasic ß-TCP vs. biphasic HA/ß-TCP in two-stage sinus floor augmentation procedures - a prospective randomized clinical trial.

OBJECTIVES: To compare a monophasic (100% ß-TCP) and a biphasic (60% HA and 40% ß-TCP) bone substitute material (BSM) regarding biocompatibility, osteoconductivity and implant stability using histological, radiological and resonance frequency analysis. MATERIAL AND METHODS: Sixty-seven sinus floor elevations were performed in 60 patients. One patient group (monophasic bone substitute [MBS], 30 patients, 32 sinuses) was augmented by the use of the monophasic material (Bioresorb® , Sybron Implant Solutions, Bremen, Germany), while the second group (biphasic bone substitute (BBS), 30 patients, 35 sinuses) received a biphasic material (Maxresorb® , Botiss Biomaterials, Berlin, Germany). Cone beam CT images were taken immediately after augmentation and prior to implant placement after 6 months. Trephines were harvested, while the implant bed was prepared. Resonance frequency analysis was performed immediately after implant placement and 6 months later. Descriptive analysis was performed on all augmented sinus (n = 67). For statistical comparison of the groups, one sinus of each bilaterally treated patient was randomly excluded, resulting in 30 sinuses grafted with MBS and 30 sinuses grafted with BBS (n = 60). RESULTS: Histomorphometrical analysis of all sinuses displayed comparable results for both groups regarding new bone matrix (MBS 36.16 ± 19.37%, BBS 38.42 ± 12.61%), residual BSM (MBS 30.26 ± 11.7%, BBS 32.66 ± 12.57%) and non-mineralized tissue (MBS 34.29 ± 18.32%, BBS 28.92 ± 15.04) %) (P > 0.05, respectively). Radiological volume of BBS was significantly more stable (volume loss of 22.2% for MBS, 6.66% for BBS; P < 0.001), and homogeneity of the graft after 6 months was higher for BBS than that for MBS (P < 0.05). Resonance frequency analysis endorsed a higher implant stability quotient for BBS after 6 months than that for MBS (MBS 78.31 ± 5.81, BBS 80.42 ± 6.31; P < 0.05, Mann-Whitney U-test, respectively). CONCLUSION: Both monophasic and biphasic materials show good biocompatibility and osteoconductivity with satisfactory support on implant stability. BBS remains more stable in terms of volume maintenance and radiological graft homogeneity after a healing period of 6 months.

Histological and radiological evaluation of sintered and non-sintered deproteinized bovine bone substitute materials in sinus augmentation procedures. A prospective, randomized-controlled, clinical multicenter study.

OBJECTIVES: The objective of this study is to histologically and radiologically compare a sintered and a non-sintered bovine bone substitute material in sinus augmentation procedures. MATERIALS AND METHODS: Thirty-three patients were included in the clinically controlled randomized multicentre study resulting in a total of 44 treated sinuses. After lateral approach, sinuses were filled with either a sintered (SBM, Alpha Bio's Graft®) or a non-sintered (NSBM, Bio Oss®) deproteinized bovine bone substitute material. The augmentation sites were radiologically assessed before and immediately after the augmentation procedure as well as prior to implant placement. Bone trephine biopsies for histological analysis were harvested 6 months after augmentation whilst preparing the osteotomies for implant placement. RESULTS: Healing was uneventful in all patients. After 6 months, radiological evaluation of 43 sinuses revealed a residual augmentation height of 94.65 % (±2.74) for SBM and 95.76 % (±2.15) for NSBM. One patient left the study for personal reasons. Histological analysis revealed a percentage of new bone of 29.71 % (±13.67) for SBM and 30.57 % (±16.07) for NSBM. Residual bone substitute material averaged at 40.68 % (±16.32) for SBM compared to 43.43 % (±19.07) for NSBM. All differences between the groups were not statistically significant (p > 0.05, Student's t test). CONCLUSION: Both xenogeneic bone substitute materials showed comparable results regarding new bone formation and radiological height changes in external sinus grafting procedures. CLINICAL RELEVANCE: Both bone substitute materials allow for a predictable new bone formation following sinus augmentation procedures.

Accuracy of cone beam computed tomography in assessing peri-implant bone defect regeneration: a histologically controlled study in dogs.

OBJECTIVE: To assess the accuracy of cone-beam computed tomography (CBCT) in terms of buccal bone-wall configuration and peri-implant bone defect regeneration after guided bone regeneration (GBR). MATERIAL AND METHODS: Titanium implants were inserted into standardized box-shaped defects in the mandible of 12 foxhounds. Defects of one side were augmented following the principle of GBR, while the other side was left untreated. Radiological evaluation was performed using CBCT and compared with histomorphometrical measurements of the respective site serving as a validation method. RESULTS: Non-augmented control sites providing a horizontal bone width (BW) of<0.5 mm revealed a significantly lower accuracy between the radiological and the histological evaluation of the buccal defect depth (1.93 ± 1.59 mm) compared with the group providing a BW of >0.5 mm (0.7 ± 0.7 mm) (P<0.05, Mann-Whitney U-test). In GBR-treated defects, the subgroup <0.5 mm (1.49 ± 1.29 mm) revealed a significantly higher difference between CBCT and histology compared with >0.5 mm (0.82 ± 1.07) (P>0.05, Mann-Whitney U-test). However, a radiological discrimination between original bone, integrated and non-integrated bone substitute material was not reliable. Additionally, it was found that a minimum buccal BW of 0.5 mm was necessary for the detection of bone in radiology. CONCLUSION: The evaluation of peri-implant bone defect regeneration by means of CBCT is not accurate for sites providing a BW of <0.5 mm. Moreover, a safe assessment of the success of the GBR technique is not possible after the application of a radiopaque bone substitute material.

Impact of machined versus structured implant shoulder designs on crestal bone level changes: a randomized, controlled, multicenter study.

PURPOSE: The collar region of an implant is its connection to the oral cavity. A balance between osseointegration on one hand and the absence of plaque accumulation on the other hand is necessary for successful implantation. It is yet to be determined which implant collar design, polished or rough, is best to stabilize the crestal bone level, avoiding peri-implantitis and subsequent risk of implant loss. The aim of this study was to investigate the influence of the architecture of the collar region on marginal bone and soft tissue response. METHODS: This prospective, randomized, clinically controlled multicenter study included 58 patients undergoing dental implant treatment using a pair of dental implants with either machined or rough-surfaced shoulder regions. Patients were clinically and radiologically examined for bone level height and signs of inflammation after 6, 12 and 24 months. RESULTS: No implant was lost within the 2 years of follow-up (100% survival rate). No significant differences on crestal bone loss (machined neck: 0.61 mm ± 0.28 mm, rough neck 0.58 mm ± 0.24 mm) and on soft tissue response (probing depth 3-6 mm with bleeding on probing 7.6% in machined-neck implants and in 8.3% in rough neck implants) were observed between implants with machined and roughened neck after 2 years. CONCLUSIONS: Machined and roughened neck implants achieved equally good results concerning peri-implant bone loss, the rate of peri-implantitis and implant survival rate/hard and soft tissue integration. None of the two collar designs showed a clear advantage in peri-implant reaction. Trial registration German Clinical Trials Register, DKRS00029033. Registered 09 May 2022-Retrospectively registered, http://www.dkrs.de.

Comparison of the Validity of Enzymatic and Immunohistochemical Detection of Tartrate-resistant Acid Phosphatase (TRAP) in the Context of Biocompatibility Analyses of Bone Substitutes.

BACKGROUND/AIM: Macrophages and biomaterial-induced multinucleated giant cells (BMGCs) are central elements in the tissue reaction cascade towards bone substitute materials (BSM). The enzymatic detection of the lytic enzyme tartrate-resistant acid phosphatase (TRAP) has manifoldly been used to examine the so-called "bioactivity" of BSM. The present study aimed to compare the detection validity and expression pattern of the TRAP enzyme using enzymatic and immunohistochemical detection methods in the context of biocompatibility analyses of BSM. PATIENTS AND METHODS: Biopsies from 8 patients were analyzed after sinus augmentation with a xenogeneic bone substitute. Analysis of both macrophage and BMGC polarization were performed by histochemical TRAP detection and immunohistochemical detection of TRAP5a. Histomorphometrical analysis was used for comparison of the TRAP detection of BMGCs. RESULTS: The enzymatic TRAP detection method revealed that in 7 out of 8 biopsies only single cells were TRAP-positive, whereas most of the cells and especially the BMGCs were TRAP-negative. The immunohistochemical detection of TRAP5a showed moderate numbers of stained mononuclear cells, while the majority of the BMGCs showed signs of TRAP5a-expression. The enzymatic TRAP detection was comparable to the results obtained via immunohistochemistry only in one case. The histomorphometrical analysis showed that significantly more mononuclear and multinucleated TRAP-positive cells were found using immunohistochemical TRAP5a-staining compared to the enzymatic TRAP detection method. Also, significantly more TRAP-negative BMGCs were found using the enzymatic TRAP detection. CONCLUSION: The immunohistochemical detection of TRAP is more accurate for examination of the bioactivity and cellular degradability of BSM.

The use of solvent-preserved human and bovine cancellous bone blocks for lateral defect augmentation - an experimental controlled study in vivo.

BACKGROUND: The aim of this study was to compare new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material in laterally augmented alveolar bone defects using allogeneic, pre-treated and cleaned human bone blocks (tested in dogs, therefore considered to be xenogeneic), and pre-treated and cleaned bovine cancellous bone blocks, both with and without a collagen membrane in order to evaluate their augmentative potential. METHODS: Thirty-two critical size horizontal defects were prepared in the mandible of 4 adult foxhound dogs (8 per dog, 4 on each side). After 3 months of healing, the defects were laterally augmented in a split-mouth-design with either human (HXB) or bovine solvent-preserved bone blocks (BXB). Afterwards, defects were randomly covered with a bovine collagenous membrane (HXB + M, BXB + M). After a healing interval of 6 months, percentages of new bone formation, resorbed bone matrix, and fibrous enclosed residual bone substitute material were compared. RESULTS: Results showed little new bone formation of up to 3.7 % in human bone blocks (HXB 3.7 % ± 10.2, HXB + M 0.3 %± 0.4, BXB, 0.1 % ± 0.8, BXB + M 2.6 % ± 3.2, p = > 0.05). Percentages of fibrous encapsulation were higher in human bone blocks than in bovine bone blocks (HXB 71.2 % ± 8.6, HXB + M 73.71 % ± 10.6, BXB, 60.5 % ± 27.4, BXB + M 52.5 % ± 28.4, p = > 0.05). Resorption rates differed from 44.8 % in bovine bone blocks covered with a membrane to 17.4 % in human bone blocks (HXB 17.4 % ± 7.4, HXB + M 25.9 % ± 10.7, BXB, 38.4 % ± 27.2, BXB + M 44.8 % ± 29.6, p = > 0.05). The use of additional membranes did not significantly affect results. CONCLUSIONS: Within its limitations, results of this study suggest that solvent-preserved xenogenic human and bovine bone blocks are not suitable for lateral bone augmentation in dogs. Furthermore, defect coverage with a membrane does not positively affect the outcome.

Impact of guided bone regeneration and defect dimension on wound healing at chemically modified hydrophilic titanium implant surfaces: an experimental study in dogs.

OBJECTIVES: The aim of the present study was to evaluate the impact of guided bone regeneration and defect dimension on wound healing at chemically modified titanium implant surfaces (modSLA). MATERIALS AND METHODS: ModSLA implants were placed at chronic-type lateral ridge defects of different heights (H1-H4: 2, 4, 6 and 8 mm) and randomly allocated to either (a) GBR (polyethylene glycol membrane + biphasic calcium phosphate) or (b) untreated control. At 2 and 8 weeks (n=6 dogs each), dissected blocks were processed for histomorphometrical analysis [e.g., percentage linear fill (PLF), regenerated area (RA)]. RESULTS: At 8 weeks, both groups revealed comparable mean PLF (%) [ CONTROL: H1 (26.1 +/- 5.8)-H4 (60.4 +/- 11.8); GBR: H1 (8.3 +/- 5.3)-H4 (50.7 +/- 23.1)] and RA (mm(2)) [ CONTROL: H1 (2.5 +/- 0.4)-H4 (7.4 +/- 4.1); GBR: H1 (1.8 +/- 1.0)-H4 (10.8 +/- 5.9)] values. A significant difference was observed for the mean PLF values at H1 defects. CONCLUSION: It was concluded that (i) modSLA titanium implants supported bone regeneration and osseointegration at H1-H4 defects and (ii) the present GBR procedure did not seem to improve the outcome of vertical bone regeneration, but tended to increase the mean RA values.

Comparison of Material-mediated Bone Regeneration Capacities of Sintered and Non-sintered Xenogeneic Bone Substitutes via 2D and 3D Data.

BACKGROUND/AIM: The aim of this study was the development of a new osteoconductivity index to determine the bone healing capacities of bone substitute materials (BSM) on the basis of 3D microcomputed tomographic (µ-CT) data. MATERIALS AND METHODS: Sinus biopsies were used for the comparative analysis of the integration behavior of two xenogeneic BSM (cerabone® and Bio-Oss®). 3D µ-CT and data sets from histomorphometrical measurements based on 2D histological slices were used to measure the bone-material-contact and the tissue distribution within the biopsies. The tissue reactions to both BSM were microscopically analyzed. RESULTS: The 3D and 2D results of the osteoconductivity measurements showed comparable material-bone contacts for both BSM, but the 2D data were significantly lower. The same results were found when tissue distribution was measured in both groups. The histopathological analysis showed comparative tissue reactions in both BSM. CONCLUSION: Osteoconductivity index is a reliable measurement parameter for determining the healing capacities of BSM. The observed differences between both measurement methods could be assigned to the resolution capacity of µ-CT data that did not allow for a precise interface distinction between both BSM and bone tissue. Histomorphometrical data based on histological slides still allow for a more exact evaluation.

Prevention of post-operative bleeding in hemostatic compromised patients using native porcine collagen fleeces-retrospective study of a consecutive case series.

INTRODUCTION: Various anticoagulant therapy regimes bear the risk of postsurgical bleeding events after dental extractions. Local hemostyptic measures, e.g., collagen fleeces, are applied by surgeons to prevent such bleedings. No standard protocol in prevention of bleeding events has met general acceptance among surgeons yet. PURPOSE: The purpose of this retrospective study was to determine if post-operative bleeding can be prevented by suturing native collagen fleeces into extraction wounds immediately after teeth removal, regardless what anticoagulant regime is performed. METHODS: A total of 741 extraction units were removed from 200 consecutive in-ward patients with or without alternation of different anticoagulant therapy regimes. Anti-vitamin K agents were the most prescribed drugs (n = 104, 52 %), followed by Acetylsalicylate (ASS) (n = 78, 39 %). Nineteen (9.5 %) patients received a dual anti-platelet therapy. Out of 104 patients receiving an anti-vitamin K agent (phenprocoumon), 84 patients were bridged, 20 patients continued to their anticoagulant therapy without alterations. Following careful tooth extraction, extraction sockets were filled using a native type I and III porcine collagen sponge (Collacone, Botiss Biomaterials, Berlin), supported by single and mattress sutures for local hemostasis. Post-operative bleeding events were rated according to their clinical relevance. RESULTS: In the post-operative phase, 8 out of 200 consecutively treated patients experienced a post-operative bleeding event. All of them had been designated for a long-term anti-vitamin K therapy (p ≤ 0.05), and extractions were performed under a heparin bridging regime (n = 6) or an uninterrupted anti-vitamin K agent therapy (n = 2). No bleeding events occurred in patients with ASS 100 therapy or low-dose LMWH therapy (p ≤ 0.05), or in patients with dual anti-platelet therapy (0 out of 24). None of the bleeding events put patients' health at risk or required systemic intervention. CONCLUSION: Sufficiently performed local hemostyptic measures, like the application of collagen fleeces in combination with atraumatic surgery, bears a great potential for preventing heavy bleeding events in hemostatic compromised patients, regardless of their anticoagulant therapy.

Biodegradation pattern and tissue integration of native and cross-linked porcine collagen soft tissue augmentation matrices - an experimental study in the rat.

INTRODUCTION: Within the last decades, collagen types I and III have been established as a sufficient biomaterial for GBR and GTR procedures. They might also be an adequate matrix for soft tissue augmentations. However, collagen materials differ significantly regarding resorption time, biodegradation pattern and the invasion of inflammatory cells.The aim of the present study was to compare the biodegradation and tissue integration of native, differently processed and cross-linked collagen scaffolds in rats. METHODS: Four experimental porcine collagen matrices of 1.0 mm thickness, developed for soft tissue augmentation procedures, were tested. Based on the same native dermal Type I and III collagen, native (ND, Mucoderm prototype), specifically defatted (DD), ethylene dioxide cross-linked (ECL) and dehydrothermally cross-linked (DCL) dermis collagen (AAP/Botiss Biomaterials, Berlin, Germany) were evaluated. Two specimens of 1 × 1 cm were fixed around a non-absorbable spacer using non-absorbable sutures. After rehydration, specimens (N = 8) were randomly allocated in unconnected subcutaneous pouches on the back of 40 Wistar rats. Rats were divided into five groups (1, 2, 4, 8 and 12 weeks), including eight animals each. After each period, eight rats were sacrificed and explanted specimens were prepared for histological analysis. The following parameters were evaluated: membrane thickness as a sign of biodegradation and volume stability, cell ingrowth, vascularization, tissue integration and foreign body reaction. RESULTS: Biodegradation pattern of the non cross-linked collagen scaffolds differed only slightly in terms of presence of inflammatory cells and cell invasion into the matrix. In terms of biodegradation, ECL displayed a considerable slower resorption than ND, DCL and DD. Chemical cross-linking using ethylene dioxide showed a significant higher invasion of inflammatory cells. CONCLUSION: Within the limits of the present study it was concluded that the processing techniques influenced the collagen properties in a different intensity. Dehydrothermal cross-linking and special defatting did not notably change the biodegradation pattern, whereas cross-linking using ethylene dioxide led to significant higher volume stability of the matrix. However, ECL showed an increased inflammatory response and compromised tissue integration. Therefore, ethylene dioxide seems to be not suitable for stabilization of collagen matrices for soft tissue augmentation procedures.

Biocompatibility and biodegradation of a native porcine pericardium membrane: results of in vitro and in vivo examinations.

PURPOSE: The principle of guided tissue and bone regeneration has long been established for treating bone and periodontal defects. In addition to nonabsorbable barriers, various collagens have become accepted as membrane materials for separating the graft from soft tissue. However, collagen membranes differ significantly in their barrier function and biocompatibility. The objective of this pilot study was to examine, in vitro and in vivo, a novel native collagen membrane extracted from porcine pericardium. MATERIALS AND METHODS: The morphologic structure of two different native collagen membranes (Remotis, Thommen Medical; Bio-Gide, Geistlich Biomaterials) was examined using a scanning electron microscope. For biocompatibility testing, membranes were incubated with SaOs-2 osteoblastlike cells. After 2 hours, 3 days, and 7 days, proliferation of the cells on the membranes was determined. Evaluation of the biodegradation pattern was performed in a dog model with simultaneous bone augmentation with Bio-Oss (Geistlich Biomaterials) or Cerabone (Botiss Biomaterials) in the lateral anterior maxilla in eight animals with histologic examination after 4, 8, 12, and 24 weeks. RESULTS: An interconnective pore system was identifiable for Remotis, while Bio-Gide displayed a more fibrous structure. In vitro, Remotis showed considerable cell proliferation, which was significantly superior to that observed with Bio-Gide, especially after 7 days (2,910 ± 1,273 and 707 ± 706, respectively). In vivo, both membranes integrated into the surrounding tissue without any inflammatory reaction. Both membranes allowed early vascularization. However, considerable biodegradation was noted within 4 to 8 weeks with Bio-Gide, while Remotis resorbed generally within the first 8 to 12 week. Both membranes supported underlying bone formation. CONCLUSION: Both examined membranes indicate a high level of biocompatibility. Both are resorbed without inflammation within 8 weeks (Bio-Gide) or 12 weeks (Remotis). The compact interconnective pericardium collagen of Remotis may have stabilized the resorption process.