Alveolar bone repair with strontium- containing nanostructured carbonated hydroxyapatite

ABSTRACT Objective: This study aimed to evaluate bone repair in rat dental sockets after implanting nanostructured carbonated hydroxyapatite/sodium alginate (CHA) and nanostructured carbonated hydroxyapatite/sodium alginate containing 5% strontium microspheres (SrCHA) as bone substitute materials. Methods: Twenty male Wistar rats were randomly divided into two experimental groups: CHA and SrCHA (n=5/period/group). After one and 6 weeks of extraction of the right maxillary central incisor and biomaterial implantation, 5 μm bone blocks were obtained for histomorphometric evaluation. The parameters evaluated were remaining biomaterial, loose connective tissue and newly formed bone in a standard area. Statistical analysis was performed by Mann-Withney and and Wilcoxon tests at 95% level of significance. Results: The histomorphometric results showed that the microspheres showed similar fragmentation and bio-absorbation (p>0.05). We observed the formation of new bones in both groups during the same experimental periods; however, the new bone formation differed significantly between the weeks 1 and 6 (p=0.0039) in both groups. Conclusion: The CHA and SrCHA biomaterials were biocompatible, osteoconductive and bioabsorbable, indicating their great potential for clinical use as bone substitutes.

Accelerated Healing Period with Hydrophilic Implant Placed in Sheep Tibia

Abstract The objective of this study was to evaluate the early osseointegration of two different implants surfaces, a sandblasted and acid-etched surface (TN) compared with same geometry and surface roughness modified to be hydrophilic/wettable by conditioning in an isotonic solution of 0.9% sodium-chloride (TA) through histological and histomorphometric analysis after sheep tibia implantation. Forty dental implants, divided in two groups (TN and TA) were placed in the left tibia of twenty healthy, skeletally mature Santa Ines sheep (n=5/experimental period). After 7, 14, 21 and 28 days post-implantation, the samples were removed and the sheep were kept alive. Analysis of resin sections (30 μm) allowed the quantification of bone area (BA) and bone-to-implant contact (BIC). TA group presented nearly 50% increase in BA at 14 days (p<0.001, ANOVA - Tukey's post test) compared with 7 days. The TA presented higher values than the TN for BA and BIC at 14, 21, and 28 days after placement, stabilizing bone healing. TA hydrophilic surface promoted early osseointegration at 14 and 21 days compared to TN, accelerating bone healing period post-implant placement in sheep tibia.

Resumo O objetivo deste estudo foi avaliar a osseointegração precoce de duas superficies diferentes de implantes, uma superfície tratada com jateamento e ataque ácido (TN) comparada com outra superfície com a mesma geometria e rugosidade e modificada com hidrofilicidade / molhabilidade através do condicionamento em solução isotônica de 0,9% de cloreto de sódio (TA) através de análises histológica e histomorfométrica após a implantação em tíbia de ovelhas. Quarenta implantes dentários, divididos em dois grupos (TN e TA), foram implantados na tíbia esquerda de vinte ovelhas Santa Inês (n=5/período experimental) saudáveis e esqueleticamente maduras. Após 7, 14, 21 e 28 dias pós-implantação, as amostras foram coletadas e as ovelhas foram mantidas vivas. A análise dos cortes em resina (30 μm) permitiu a quantificação da área de osso (BA) e do contato osso-implante (BIC). O grupo TA apresentou aumento de quase 50% na BA aos 14 dias (p <0,001, ANOVA - pós teste de Tukey) em comparação com 7 dias. O grupo TA apresentou valores maiores do que o TN para BA e BIC aos 14, 21 e 28 dias após a implantação, estabilizando a cicatrização óssea. A superfície hidrofílica TA promoveu uma osseointegração precoce aos 14 e 21 dias em relação à TN, acelerando o período de cicatrização óssea após a instalação dos implantes em tíbias de ovelha.

Physico-chemical and Histomorphometric Evaluation of Zinc-containing Hydroxyapatite in Rabbits Calvaria

Abstract The aim of this study was to characterize the physico-chemical properties and bone repair after implantation of zinc-containing nanostructured porous hydroxyapatite scaffold (nZnHA) in rabbits' calvaria. nZnHA powder containing 2% wt/wt zinc and stoichiometric nanostructured porous hydroxyapatite (nHA - control group) were shaped into disc (8 mm) and calcined at 550 °C. Two surgical defects were created in the calvaria of six rabbits (nZnHA and nHA). After 12 weeks, the animals were euthanized and the grafted area was removed, fixed in 10% formalin with 0.1 M phosphate buffered saline and embedded in paraffin (n=10) for histomorphometric evaluation. In addition, one sample from each group (n=2) was embedded in methylmethacrylate for the SEM and EDS analyses. The thermal treatment transformed the nZnHA disc into a biphasic implant composed of Zn-containing HA and Zn-containing β-tricalcium phosphate (ZnHA/βZnTCP). The XRD patterns for the nHA disc were highly crystalline compared to the ZnHA disc. Histological analysis revealed that both materials were biologically compatible and promoted osteoconduction. X-ray fluorescence and MEV-EDS of nZnHA confirmed zinc in the samples. Histomorphometric evaluation revealed the presence of new bone formation in both frameworks but without statistically significant differences (p>0.05), based on the Wilcoxon test. The current study confirmed that both biomaterials improve bone repair, are biocompatible and osteoconductive, and that zinc (2wt%) did not increase the bone repair. Additional in vivo studies are required to investigate the effect of doping hydroxyapatite with a higher Zn concentration.

Resumo O objetivo deste estudo foi caracterizar físico-químicamente e avaliar o reparo ósseo de discos de hidroxiapatita porosa contendo zinco após a implantação em calvária de coelhos (nZnHA). O pó de nZnHA e o pó hidroxiapatita porosa estequiométrica nanoestruturada (controle - nHA) foram confeccionados em discos (8 mm) e calcinados a 550˚C. Dois defeitos cirúrgicos foram criados na calvária de seis coelhos para a implantação dos discos. Após 12 semanas, os animais foram eutanasiados e as áreas enxertadas foram removidas, fixadas em formol a 10% e embebidas em parafina (n=10) para avaliação histomorfométrica. Além disso, uma amostra de cada grupo (n=2) foi embebida em metilmetacrilato para análise de MEV e EDS. O tratamento térmico dos discos de nZnHA transformou-os em implantes bifásicos compostos por HA contendo Zinco e β fosfato tricálcico com Zinco (ZnHA/βZnTCP). Os discos de nHA, apresentaram-se altamente cristalinos e com baixa solubilidade quando comparados aos discos de ZnHA. A análise histológica revelou que ambos os materiais foram biologicamente compatíveis e promoveram a osteocondução. As análises de FRX e MEV-EDS confirmaram a presença do zinco nas amostras de nZnHA. A avaliação histomorfométrica revelou a presença de neoformação óssea em ambos os grupos, porém sem diferenças estatísticas entre eles, com base no teste de Wilcoxon (p>0,05). O presente estudo confirmou que ambos os biomateriais otimizaram o reparo ósseo, foram biocompatíveis e osseocondutivos e a presença do zinco não favoreceu o reparo ósseo. Estudos adicionais in vivo devem ser conduzidos a fim de investigar o efeito de maiores concentrações de zinco.

Study of bone healing pattern in extraction socket after application of demineralized dentin matrix material

INTRODUCTION: Research on dental bone graft material has been actively conducted. Recently, demineralized dentin matrix material has been developed and introduced. This study examined the effect of demineralized dentin matrix material on bone healing. SUBJECTS AND METHODS: The patients who received no treatment after extraction were used as the control group and patients who underwent demineralized dentin matrix material application in the extraction socket after extraction were used as the experimental group. Panorama radiography was performed at the baseline and at 3.5 months after graft material placement and CT was taken at 3.5 months after graft material placement for a radiologic evaluation. Bony tissue specimens were collected from the alveolar crest in the middle of the extraction socket using a 2 mm trephine bur after 3.5 months for the histology and hostomorphometric study. RESULTS: 1. On the panoramic view, a higher bone density was observed in the subject group. 2. On the panoramic view, the bone density increased significantly in the extraction socket, from the baseline to 3.5 months: a 7 and 10 gray-level scale was observed in the control and experimental group, respectively (P<0.05). 3. The CT view evaluation at 3.5 months revealed significantly higher bone density in the subject group than the control group (P<0.05). 4. The histological findings showed more active new bone and lamellar bone formation in the subject group. Dentin with osteoinduction ability and enamel with osteoconduction ability appeared. 5. On histomorphometric analysis, the subject group showed significantly more new bone, lamellar bone area and lower soft tissue area (P<0.05). The difference between the groups was significant (P<0.05). CONCLUSION: Bone healing was improved after the application of demineralized dentin matrix material and there was active new bone and lamellar bone formation.