Peter Abrahamsson

Periapical Tissue Response After Use of Intermediate Restorative Material, Gutta- Percha, Reinforced Zinc Oxide Cement, and Mineral Trioxide Aggregate as Retrograde Root-End Filling Materials: A Histologic Study in Dogs

PURPOSE To investigate the periapical tissue response of 4 different retrograde root-filling materials, ie, intermediate restorative material, thermoplasticized gutta-percha, reinforced zinc oxide cement (Super-EBA), and mineral trioxide aggregate (MTA), in conjunction with an ultrasonic root-end preparation technique in an animal model. MATERIALS AND METHODS Vital roots of the third and fourth right mandibular premolars in 6 healthy mongrel dogs were apicectomized and sealed with 1 of the materials using a standardized surgical procedure. After 120 days, the animals were sacrificed and the specimens were analyzed radiologically, histologically, and scanning electron microscopically. The Fisher exact test was performed on the 2 outcome values. RESULTS Twenty-three sections were analyzed histologically. Evaluation showed better re-establishment of the periapical tissues and generally lower inflammatory infiltration in the sections from teeth treated with the intermediate restorative material and the MTA. New root cement on the resected dentin surfaces was seen on all sections regardless of the used material. New hard tissue formation, directly on the surface of the material, was seen only in the MTA sections. There was no statistical difference in outcome among the tested materials. CONCLUSIONS The results from this dog model favor the intermediate restorative material and MTA as retrograde fillings when evaluating the bone defect regeneration. MTA has the most favorable periapical tissue response when comparing the biocompatibility of the materials tested.

Periapical surgery using ultrasonic preparation and thermoplasticized gutta-percha with AH Plus sealer or IRM as retrograde root-end fillings in 160 consecutive teeth: a prospective randomized clinical study

OBJECTIVE The aim of this study was to evaluate the healing outcome after periapical surgery with an ultrasonic cleaning technique in conjunction with the use of either of 2 different retrograde root-filling materials in teeth with apical periodontitis. STUDY DESIGN One hundred sixty teeth in 139 consecutive patients were randomly allocated into 2 groups receiving either IRM or thermoplasticized gutta-percha (GP) with AH Plus sealer as a retrograde root-end seal. The patients were reviewed 12 months after surgery. The results were analyzed with Fisher exact test. RESULTS One hundred forty-seven teeth in 131 patients were reviewed. Radiologic evaluation and clinical examination showed an 85% success rate for the IRM group and 90% for GP group. There was no statistical significance between the 2 groups. CONCLUSION Both tested materials, IRM and GP, are suitable as retrograde root-end filling materials in conjunction with ultrasonic root-end preparation according to the results of the healing outcome after 12 months follow-up.

Periosteal expansion of rabbit mandible with an osmotic self-inflatable expander.

We aimed to evaluate a new technique for intraoral expansion of soft tissue with a self-inflatable expander in rabbits. We placed a self-inflatable soft tissue expander bilaterally in eight rabbits under the periosteum of the mandible through an extraoral approach. The expander was left to self-inflate for two weeks, after which the animals were killed and specimens collected for histological examination. The self-inflatable soft tissue expanders expanded the periosteum. There were no dehiscences or infections. Histological observations showed no signs of any inflammatory reaction and there was no evidence of bony resorption. New bone had formed at the edges of the expanded periosteum. In the control area no new bone had formed. The osmotic soft tissue expander model for intraoral soft tissue and periosteal expansion suggests a promising way of creating a surplus of soft tissue that can be used to cover bone grafts.

Periosteal Expansion Before Local Bone Reconstruction Using a New Technique for Measuring Soft Tissue Profile Stability : A Clinical Study

PURPOSE To evaluate the outcome of intraoral soft tissue expansion by measuring the profile change using objective 3D metering equipment and to evaluate localized bone grafting after soft tissue expansion with regard to gain of bone and complications. MATERIALS AND METHODS Using a prospective study design, we asked patients with an osseous and soft tissue defect on the buccal aspect of the alveolar process to participate in this study. In 10 patients (experimental group) a self-inflatable soft tissue expander was placed under the periosteum. After 2 weeks, the expander was removed and a particulated onlay bone graft was placed in the expanded area, protected by a titanium mesh covered with a collagen membrane. Ten patients (reference group) were treated with a mandibular ramus bone block graft. The soft tissue profile was registered before each surgical procedure. The vertical and lateral dimensions of the bone grafts were noted at the grafting procedure and at the implant installation. P < .05 was considered significant. RESULTS The mean soft tissue profile change was 2.9 ± 1.1 mm after soft tissue expansion and 2.3 ± 2.1 mm at implant placement in the experimental group compared with 1.5 ± 1.4 mm at implant placement in the reference group (P = .065). Two patients had minor perforations of the soft tissue expander. In the experimental group, the mean lateral bone augmentation after soft tissue expansion was 4.5 ± 1.3 mm, and after healing, it decreased to 3.9 ± 1.4 mm (P = .063). The mean vertical augmentation was 4.1 ± 1.7 mm and had decreased at implant placement to 3.0 ± 1.4 mm (P = .041). In the reference group, the mean lateral augmentation was 3.8 ± 0.8 mm, and after healing, it reduced to 2.7 ± 0.8 mm (P = .024). The mean vertical augmentation was 2.9 ± 0.9 mm, and after healing of the bone graft at implant placement, it was reduced to 1.6 ± 0.8 mm (P = .01). When smokers were excluded, there was significantly less resorption of the bone grafts in both lateral (P = .049) and vertical (P = .012) dimensions in the experimental group compared with the reference group. CONCLUSION Hydrogel expansion of the periosteum is an applicable method to achieve a surplus of soft tissue to cover bone grafts. More refinements to the technique may be required to minimize complications, especially in smoking patients.

Onlay bone grafting of the mandible after periosteal expansion with an osmotic tissue expander: an experimental study in rabbits

OBJECTIVES To evaluate the space-maintaining capacity of a titanium mesh or a bioresorbable mesh after periosteal expansion and to assess bone formation under a titanium mesh or a bioresorbable mesh on the lateral border of the mandible by qualitative and quantitative histological analysis. MATERIAL AND METHODS In 13 rabbits, a self-inflatable soft tissue expander was placed intraorally, bilaterally under the mandibular periosteum via an extra oral approach. After 2 weeks, the expanders were removed and a particulated onlay bone graft was placed and covered by a titanium mesh or a bioresorbable mesh. After 3 months, the animals were sacrificed and specimens were collected for histology. RESULTS The osmotic soft tissue expander created a subperiosteal pocket and a ridge of new bone had formed at the edges of the expanded periosteum in all sites. After the healing period of 3 months, soft tissue dehiscence was recorded in two of the sites with bioresorbable meshes. The mean bone fill was 65% under the titanium mesh and 85% under the bioresorbable mesh (P<0.05). There was no significant difference between the titanium mesh and the bioresorbable mesh regarding the height of the meshes, mesh area and mineralized bone area. Scanning electron microscopy shows that new bone is growing in direct contact with the resorbable mesh and the titanium mesh. CONCLUSION This study confirms that an osmotic soft tissue expander creates a surplus of periosteum and soft tissue and that new bone can be generated under a titanium mesh or bioresorbable mesh.

Guided bone generation in a rabbit mandible model after periosteal expansion with an osmotic tissue expander.

OBJECTIVES To evaluate the space-maintaining capacity of titanium mesh covered by a collagen membrane after soft tissue expansion on the lateral border of the mandible in rabbits, and to assess bone quantity and quality using autogenous particulate bone or bone-substitute (Bio-Oss(®) ), and if soft tissue ingrowth can be avoided by covering the mesh with a collagen membrane. MATERIAL AND METHODS In 11 rabbits, a self-inflatable soft tissue expander was placed under the lateral mandibular periosteum via an extra-oral approach. After 2 weeks, the expanders were removed and a particulated onlay bone graft and deproteinized bovine bone mineral (DBBM) (Bio-Oss(®) ) were placed in the expanded area and covered by a titanium mesh. The bone and DBBM were separated in two compartments under the mesh with a collagen membrane in between. The mesh was then covered with a collagen membrane. After 3 months, the animals were sacrificed and specimens were collected for histology. RESULTS The osmotic soft tissue expander created a subperiosteal pocket and a ridge of new bone formed at the edges of the expanded periosteum in all sites. After the healing period of 3 months, no soft tissue dehiscence was recorded. The mean bone fill was 58.1±18% in the bone grafted area and 56.9±13.7% in the DBBM area. There was no significant difference between the autologous bone graft and the DDBM under the titanium mesh with regard to the total bone area or the mineralized bone area. Scanning electron microscopy showed that new bone was growing in direct contact with the DBBM particles and the titanium mesh. There is a soft tissue ingrowth even after soft tissue expansion and protection of the titanium mesh with a collagen membrane. CONCLUSION This study confirms that an osmotic soft tissue expander creates a surplus of periosteum and soft tissue, and that new bone can subsequently be generated under a titanium mesh with the use of an autologous bone graft or DBBM.

Guided bone augmentation using ceramic space-maintaining devices: the impact of chemistry

The purpose of the study was to evaluate histologically, whether vertical bone augmentation can be achieved using a hollow ceramic space maintaining device in a rabbit calvaria model. Furthermore, the chemistry of microporous hydroxyapatite and zirconia were tested to determine which of these two ceramics are most suitable for guided bone generation. 24 hollow domes in two different ceramic materials were placed subperiosteal on rabbit skull bone. The rabbits were sacrificed after 12 weeks and the histology results were analyzed regarding bone-to-material contact and volume of newly formed bone. The results suggest that the effect of the microporous structure of hydroxyapatite seems to facilitate for the bone cells to adhere to the material and that zirconia enhance a slightly larger volume of newly formed bone. In conclusion, the results of the current study demonstrated that ceramic space maintaining devices permits new bone formation and osteoconduction within the dome.

Guided bone regeneration using individualized ceramic sheets

Guided bone regeneration (GBR) describes the use of membranes to regenerate bony defects. A membrane for GBR needs to be biocompatible, cell-occlusive, non-toxic, and mouldable, and possess space-maintaining properties including stability. The purpose of this pilot study was to describe a new method of GBR using individualized ceramic sheets to perfect bone regeneration prior to implant placement; bone regeneration was assessed using traditional histology and three-dimensional (3D) volumetric changes in the bone and soft tissue. Three patients were included. After full-thickness flap reflection, the individualized ceramic sheets were fixed. The sites were left to heal for 7 months. All patients were evaluated preoperatively and at 7 months postoperative using cone beam computed tomography and 3D optical equipment. Samples of the regenerated bone and soft tissue were collected and analyzed. The bone regenerated in the entire interior volume of all sheets. Bone biopsies revealed newly formed trabecular bone with a lamellar structure. Soft tissue biopsies showed connective tissue with no signs of an inflammatory response. This was considered to be newly formed periosteum. Thus ceramic individualized sheets can be used to regenerate large volumes of bone in both vertical and horizontal directions independent of the bone defect and with good biological acceptance of the material.

Guided bone augmentation using a ceramic space-maintaining device

OBJECTIVE The purpose of this study was to evaluate 3-dimensionally whether vertical bone augmentation can be achieved using a hollow hydroxyapatite space-maintaining device in a rabbit calvarial model. Furthermore, different inner surface topographies, different permeabilities, and different porosities of the ceramic were tested to determine the optimal conditions for bone regeneration. STUDY DESIGN A total of 48 hollow domes made of hydroxyapatite in 4 different designs were placed subperiosteally on rabbit skull bone. The rabbits were humanely killed after 12 weeks, and the results were analyzed 3-dimensionally using micro-computed tomography. RESULTS The results suggest a larger production of bone volume when using an occlusive, dense hydroxyapatite space-maintaining device with a rough inner surface. CONCLUSIONS Hydroxyapatite space-maintaining devices permit new bone formation and osteoconduction within the dome.

Vertical bone augmentation with titanium granule blocks in rabbit calvaria

To determine whether it is possible to vertically augment bone utilizing a block graft from compressed titanium granules mainly used previously for contained bone defects and to determine whether there exists a difference in osteoconductive properties between the white and the grey granules. In 11 rabbits, 4 titanium blocks were inserted on each rabbits skull bone according to a randomized scheme. These blocks were made from standardized compressed titanium granules. Type A: PTG grey, small granules (Pourus Titanium Granules, Tigran, Malmö, Sweden); Type B: PTG grey, large granules; Type C: PTG white, small granules; Type D: PTG white large granules. After 12 weeks, the animals were sacrificed and specimens were collected for histology and μCT scanning. From both the μCT and histology, it can be said that bone formation was successfully achieved for all groups, and the granules maintained their volume. The histomorphometric BA (bone area) evaluation in the entire grafted area presented that there were no statistical differences between all groups tested. The lowest 1/4 BA in contact with the rabbit skull presented that groups A and C presented the highest mean BA, and group A presented significantly higher BA than that of group D (p = 0,049). No significant differences were noted between groups A, B and C. Within the limitation of this study, no differences were noted between small white or grey PTG blocks. The large granules presented less bone ingrowth area compared to the small granules and this trend was regardless of the different PTG types. The entire grafted area was not filled with new bone suggesting that bone migration occurred mostly from the existing cortical bone side suggesting contact osteogenesis.