Reparo alveolar após implante de vidro bioativo: avaliação histológica em macacos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise do processo de reparo alveolar em ratos espontaneamente hipertensos (SHR) não tratados e tratados com Losartan: estudo imunoistoquímico e histomorfométrico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Avaliação da reação periodontal na técnica de colagem extra-alveolar de fraturas radiculares verticais simuladas: estudo histológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Chronic graft-versus-host disease: clinical presentation of multiple lesions of lichenoid and atrophic pattern

Graft-versus-host disease is observed mainly in recipients of hematopoietic cell transplantation and is expressed by cutaneous or systemic signals and symptoms. Graft-versus-host disease is clinically classified as acute or chronic. Chronic Graft-versus-host disease occurs in up to 70% of hematopoietic cell transplanted patients and its clinical manifestations have important impact on morbidity and quality of life. The authors report an expressive cutaneous, oral and adnexal involvement in a patient with chronic Graft-versus-host disease with multiple lesions of lichenoid and atrophic pattern.

Hard and soft tissue changes around implants installed in regular-sized and reduced alveolar bony ridges. An experimental study in dogs

Objective: To study bony and soft tissue changes at implants installed in alveolar bony ridges of different widths.Material and methods: In 6 Labrador dogs, the mandibular premolars and first molars were extracted, and a buccal defect was created in the left side at the third and fourth premolars by removing the buccal bone and the inter-radicular and interdental septa. Three months after tooth extraction, full-thickness mucoperiosteal flaps were elevated, and implants were installed, two at the reduced (test) and two at the regular-sized ridges (control). Narrow or wide abutments were affixed to the implants. After 3 months, biopsies were harvested, and ground sections prepared for histological evaluation.Results: A higher vertical buccal bony crest resorption was found at the test (1.5 +/- 0.7 mm and 1.0 +/- 0.7 mm) compared to the control implants (1.0 +/- 0.5 mm and 0.7 +/- 0.4 mm), for both wide and narrow abutment sites. A higher horizontal alveolar resorption was identified at the control compared to the test implants. The difference was significant for narrow abutment sites. The peri-implant mucosa was more coronally positioned at the narrow abutment, in the test sites, while for the control sites, the mucosal adaptation was more coronal at the wide abutment sites. These differences, however, did not reach statistical significance.Conclusions: Implants installed in regular-sized alveolar ridges had a higher horizontal, but a lower vertical buccal bony crest resorption compared to implants installed in reduced alveolar ridges. Narrow abutments in reduced ridges as well as wide abutments in regular-sized ridges yielded less soft tissue recession compared to their counterparts.

A digital evaluation of alveolar ridge preservation at implants placed immediately into extraction sockets: an experimental study in the dog

Objective: To compare with pristine sites bone resorption and soft tissue adaptation at implants placed immediately into extraction sockets (IPIES) in conjunction with deproteinized bovine bone mineral (DBBM) particles and a collagen membrane.Material and methods: The mesial root of the third premolar in the left side of the mandible was endodontically treated (Test). Flaps were elevated, the tooth hemi-sectioned, and the distal root removed to allow the immediate installation of an implant into the extraction socket in a lingual position. DBBM particles were placed into the defect and on the outer contour of the buccal bony ridge, concomitantly with the placement of a collagen membrane. A non-submerged healing was allowed. The premolar on the right side of the mandible was left in situ (control). Ground sections from the center of the implant as well as from the center of the distal root of the third premolar of the opposite side of the mandible were obtained. The histological image from the implant site was superimposed to that of the contralateral pristine distal alveolus, and dimensional variation evaluated for the hard tissue and the alveolar ridge.Results: After 3 months of healing, both histological and photographic evaluation revealed a reduction of hard and soft tissue dimensions.Conclusion: The contour augmentation performed with DBBM particles and a collagen membrane at the buccal aspects of implants placed IPIES was not able to maintain the tissue volume.

Influence on alveolar resorption of the buccal bony plate width in the edentulous ridge expansion (ERE) - an experimental study in the dog

Objective: To compare the hard tissue changes at implants installed applying edentulous ridge expansion (E.R.E.) at sites with a buccal bony wall thickness of 1 or 2 mm.Material and methods: In six Labrador dogs, the first and second maxillary incisors were extracted, and the buccal alveolar bony plates and septa were removed. After 3 months of healing, partial-thickness flaps were dissected, and the E.R.E. was applied bilaterally. Hence, an expansion of the buccal bony crest was obtained in both sides of the maxilla with a displacement of either a 1- or a 2-mm-wide buccal bony plate at the test and control sites, respectively. After 3 months of healing, biopsies were obtained for histological analyses.Results: A buccal vertical resorption of the alveolar crest of 2.3 +/- 0.8 and 2.1 +/- 1.1 mm, and a coronal level of osseointegration at the buccal aspect of 2.7 +/- 0.5 and 2.9 +/- 0.9 mm were found at the test (1 mm) and control (2 mm) sites, respectively. The differences did not reach statistical significance. The mean values of the mineralized bone-to-implant contact (MBIC%) ranged from 62% to 73% at the buccal and lingual sites. No statistically significant differences were found. Horizontal volume gains of 1.8 and 1.1 mm were observed at the test and control sites, respectively, and the difference being statistically significant.Conclusions: Implants installed using the E.R.E. technique yielded a high degree of osseointegration. It is suggested that the displacement of buccal bony plates of 1 mm thickness is preferable compared with that of wider dimensions.

Connective tissue graft as a biological barrier for guided tissue regeneration in intrabony defects: a histological study in dogs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Dynamic functional impression technique fo severely resorbed alveolar ridges

The process of bone resorption can reduce the volume of the alveolar crest, which makes may make difficult impression taking of the alveolar tissue and the subsequent fit of a new denture. This clinical report describes a fast and simple technique for impressions of edentulous ridges to replace complete dentures, using a temporary tissue conditioner material on the denture base. The existing denture must cover the whole supporting area and should be in harmony with the adjacent oral structures. This technique reduces the number of steps involved and minimizes treatment time and expenses.

Behaviour of the buccal crestal bone levels after immediate placement of implants subjected to immediate loading

The aim of this study was to measure changes in buccal alveolar crestal bone levels after immediate placement and loading of dental implants with Morse taper prosthetic abutments after tooth extraction. This study followed the STROBE guidelines regarding prospective cohort studies. The sample comprised 12 patients with a mean age of 45 years, in whom a central or upper lateral incisor was indicated for extraction. Prior to extraction, computed tomography (CT) analysis was carried out to assess the presence of the buccal bone crest. CT scans were performed at 24 h and at 6 months after immediate implant placement and immediate loading. The distance from the most apical point of the implant platform to the buccal bone crest was assessed at the two time points. The buccal bone crest height was evaluated at three points in the mesio-distal direction: (1) the centre point of the alveolus, (2) 1 mm mesial to the centre point, and (3) 1 mm distal to the centre point. The values obtained were subjected to statistical analysis, comparing the distances from the bone crest to the implant platform for the two time points. After 6 months there was a statistically significant, non-uniform reduction in height at the level of the crest of the buccal bone in the cervical direction. It is concluded that the buccal bone crest of the immediate implants that replaced the maxillary incisors underwent apical resorption when subjected to immediate loading.

Dimensional changes in soft tissues around dental implants following free gingival grafting: an experimental study in dogs

ObjectiveTo study the buccal dimensional tissue changes at oral implants following free gingival grafting, with or without including the keratin layer, performed at the time of implant installation into alveolar mucosa.Material and methodsThe mandibular premolars and first molars were extracted bilaterally in six Beagle dogs. In the right side of the mandible (Test), flaps were first elevated, and the buccal as well as part of the lingual masticatory mucosa was removed. An incision of the periosteum at the buccal aspect was performed to allow the flap to be coronally repositioned. Primary wound closure was obtained. In the left side, the masticatory (keratinized) mucosa was left in situ, and no sutures were applied (Control). After 3months of healing, absence of keratinized mucosa was confirmed at the test sites. Two recipient sites were prepared at each side of the mandible in the region of the third and fourth premolars. All implants were installed with the shoulder placed flush with the buccal alveolar bony crest, and abutments were connected to allow a non-submerged healing. Two free gingival mucosal grafts were harvested from the buccal region of the maxillary canines. One graft was left intact (gingival mucosal graft), while for the second, the epithelial layer was removed (gingival connective tissue graft). Subsequently, the grafts were fixed around the test implants in position of the third and fourth premolars, respectively. After 3months, the animals were euthanized and ground sections obtained.ResultsSimilar bony crest resorption and coronal extension of osseointegration were found at test and control sites. Moreover, similar dimensions of the peri-implant soft tissues were obtained at test and control sites.ConclusionsThe increase in the alveolar mucosal thickness by means of a gingival graft affected the peri-implant marginal bone resorption and soft tissue recession around implants. This resulted in outcomes that were similar to those at implants surrounded by masticatory mucosa, indicating that gingival grafting in the absence of keratinized mucosa around implants may reduce the resorption of the marginal crest and soft tissue recession.

Sequential healing of the elevated sinus floor after applying autologous bone grafting: an experimental study in minipigs

AimTo describe the sequential healing after elevation of the maxillary sinus mucosa applying the lateral access technique with the use of autogenous bone grafting without membrane to occlude the osteotomy access.Material and methodsImmediately after the elevation of the maxillary sinus Schneiderian membrane, applying the lateral access technique in 10 minipigs, autologous bone was harvested from the lateral aspect of the mandibular molar region and ground into particles with a bone mill. The space under the Schneiderian membrane was filled with this graft. No membranes were placed onto the access osteotomy. The healing was evaluated after 15, 30, 90 and 180days. Paraffin sections were prepared and analyzed histologically.ResultsAfter 15days of healing, the elevated area was mainly filled with provisional matrix, newly formed bone and some remnants of bone chips, and appeared reduced in volume compared with that at the time of surgery. After 30days of healing, further shrinkage of the height of the elevated space was found, with similar percentages of the different tissue components. After 90 and 180days, the area underneath the Schneiderian membrane appeared reduced in volume and condensed toward the base of the sinus. The bone tissues appeared to be more mature, both for the mineralized and the non-mineralized portions, while connective tissue occupied 20% of the space, most likely related to the lack of the use of a membrane occluding the access at the time of surgery.ConclusionsSuboptimal healing outcomes with respect to augmentation of the space under the sinus floor membrane were documented when autologous bone chips were used as a filler and no membrane was applied to cover the access.

Use of autogenous bone and beta-tricalcium phosphate in maxillary sinus lifting: a prospective, randomized, volumetric computed tomography study

The correction of bone defects can be performed using autogenous or alloplastic materials, such as beta-tricalcium phosphate (β-TCP). This study compared the changes in bone volume (CBV) after maxillary sinus lifting using autogenous bone (n=12), autogenous bone associated with β-TCP 1:1 (ChronOS; DePuy Synthes, Paoli, CA, USA) (n=9), and β-TCP alone (n=11) as grafting material, by means of cone beam computed tomography (CBCT). CBV was evaluated by comparing CBCT scans obtained in the immediate postoperative period (5-7 days) and at 6 months postoperative in each group using OsiriX software (OsiriX Foundation, Geneva, Switzerland). The results showed an average resorption of 45.7±18.6% for the autogenous bone group, 43.8±18.4% for the autogenous bone+β-TCP group, and 38.3±16.6% for the β-TCP group. All bone substitute materials tested in this study presented satisfactory results for maxillary sinus lifting procedures regarding the maintenance of graft volume during the healing phase before the insertion of implants, as assessed by means of CBCT.

Segmental osteotomy for the correction of a malpositioned single implant: an 8-year follow-up

This case report is an 8-year follow-up of a malpositioned single implant, which was treated with segmental osteotomy, to confirm the treatment's characteristics, indications, and advantages. Deep buccal positioning of an endosseous implant placed in the maxillary left central incisor area did not permit acceptable prosthetic rehabilitation, despite its favorable bone insertion with no significant marginal bone loss. The surgical procedure included osteotomy and block movement performed toward the lingual and cervical position, fixed with a provisional prosthesis and miniplates and mini-implants. A connective tissue graft was necessary for esthetics optimization and was performed in a second stage. Advantages including the prevention of alveolar ridge damage, the improvement of gingival contour, and the use of an already integrated implant are presented. Clinically satisfactory hard and soft tissue stability permitted us to consider segmental surgery as a reliable alternative for malpositioned osseointegrated implants.

Influência do formato do rebordo alveolar sagital em reabilitações com associação de prótese parcial removível de extremidade livre e implante ósseo integrado

The association of mandibular distal extension removable partial dentures with an osteointegrated implant is a treatment option at hasn't been fully explored by modern rehabilitation dentistry yet. The objective of this study is to evaluate, by means of the bidimensional method of finite elements, the distribution of tension on the structures supporting the distal extension removable partial denture (DERPD), associated to a 10.0 x 3.75 mm osteointegrated implant with an ERA retention system, in alveolar ridges of different shapes. Eight models were created, representing, from a sagittal perspective: Model A (MA) – a half arch with a horizontal ridge without posterior support, with the presence of the lower left canine, and a conventional DERPD, with metallic support in the incisal aspect of this canine, as replacement for the first and second pre-molars and the first and second molars of the lower left half arch; Model B (MB) – similar to MA, but different because of the presence of a 3.75 x 10.00 mm implant with an associated ERA retention system in the posterior region of the DERPD base; Model C (MC) - similar to MA, however with a distally ascending ridge format; Model D (MD) – similar to MC, but different because there is an implant associated to a retention system; Model E (ME) - similar to MA, however with a distally descending ridge format; Model F (MF) – similar to ME, but ditfferent in the sense that there is an implant with an associated ERA retention system; Model G (MG) – similar to MA, however with a distally descending-ascending ridge format; Model H (MH) – similar to MG, but different in the sense that there is an implant with an associated ERA retention system. The finite element program ANSYS 9.0 was used to load the models with vertical forces of 50 N, on each cuspid tip. The format of distal descending edge (ME and MF) was that presented worse results, so in the models with conventional RPD as in the models with RPD associated to the implant and ERA system of retention, for the structures gingival mucosa and tooth support. 1) the distally descending ridge presented the most significant stress in the model with the conventional RPD (ME) or with a prosthesis associated to an implant (MF) and 2) the horizontal ridge (MB) provided more relief to the support structures, such as the tooth and the spongy bone, when there was an implant associated to an ERA retention system. The incorporation of the implants with the ERA system retention, in the posterior area of the toothless edge, it promotes larger stability and retention to PPREL, improving the patient's masticatory acting and, consequently, its comfort and function.