Application of the plasmatrix in alveolar ridge preservation / 口腔疾病防治

@#After tooth extraction, significant absorption occurs in the soft and hard tissues of the alveolar ridge. The goal of alveolar ridge preservation is to maintain the volume and shape of the alveolar ridge's soft and hard tissues as much as possible so as to provide suitable conditions for implant placement. Currently, there are challenges in classifying the socket for alveolar ridge preservation, such as the difficulty in directly guiding the selection of graft materials and clinical procedures and the insufficient space for particle xenograft maintenance, resulting in poor bone regeneration. Plasmatrix is an autologous blood derivative that effectively enhances tissue regeneration. This article introduced the characteristics of soft and hard tissue defects after tooth extraction and the primary applications of plasmatrix for alveolar ridge preservation (liquid plasmatrix, solid plasmatrix membrane/plug, and plasmatrix bone blocks) as well as the proposed methods for the reclassification of sockets for alveolar ridge preservation based on soft and hard tissue defects at the extraction site to facilitate the creation of clinical recommendations. The proposed classifications are as follows: Class I, extraction socket without bone defect, with or without soft tissue defect; Class Ⅱ, extraction socket with bone defect, both sides with bone wall defect less than 50%, with or without soft tissue defect; Class Ⅲ, extraction socket with bone tissue defect, at least one side with bone wall defect greater than 50%, with or without soft tissue defect. For the Class I socket, a solid plasmatrix membrane or plug is inserted, followed by injection of liquid plasmatrix, using a double-layer solid plasmatrix membrane for socket closure; for the ClassⅡ socket, plasmatrix bone blocks are inserted, followed by injection of liquid plasmatrix and secondary solidification, using absorbable collagen membrane and double-layer solid plasmatrix membrane for socket closure; for the ClassⅢ socket, tenting screws are used to maintain height, followed by implantation of plasmatrix bone blocks, injection of liquid plasmatrix and secondary solidification, using absorbable collagen membrane and double-layer solid plasmatrix membrane for socket closure. The aim of this article is to provide comprehensive knowledge of plasmatrix for oral clinicians to serve as a reference to simplify the clinical decision-making process and procedures for alveolar ridge preservation.

Application of socket-shield technique for immediate implant placement and provisionalization in esthetic zone: a case report and literature review / 口腔疾病防治

Objective@#To investigate the effect of the socket-shield technique (SST) concurrent with immediate implant placement and provisionalization (IIPP) in the aesthetic restoration of anterior teeth.@*Methods@#A case of maxillary anterior tooth stumps with a thin labial bone wall was treated with SST for preservation of labial soft and hard tissue fullness, combined with an immediate implant placement and immediate provisional crown for restoring the shape of the tooth and gingival molding@*Results@#Immediate implant placement and provisionalization restored the morphology and function of the affected tooth in the shortest possible time. The patient's labial soft and hard tissue contours in the affected tooth area were well preserved in the 18-month follow-up after the application of the SST, which presented a better aesthetic result. The literature review indicates that the indications for SST are unrestorable maxillary anterior teeth, whose dental, periodontal and periapical tissues are healthy and intact. In the esthetic zone, root shielding is effective in maintaining the soft and hard tissue contour on the labial side of the implant. However, there is no consensus on the technical details of SST, such as the ideal coronal height and thickness of the shield, and the management of the gap between the shield and the implant. Thus, more clinical studies and histologic evidence are needed to provide a reference for clinical decision-making. In addition, digital technology can improve the accuracy of implant placement and shield preparation.@*Conclusion@#The correct application of SST combined with IIPP in the esthetic zone can ensure esthetic results. However, more high-quality evidence-based medical evidence is needed for its long-term efficacy, and indications should be strictly controlled during clinical application.

Multiple idiopathic root resorption: a case report and literature review / 口腔疾病防治

Objective @#To explore the etiology, clinical manifestations, diagnosis and treatment of multiple idiopathic root resorption to provide a reference for clinical diagnosis and treatment. @*Methods@# The clinical data of a case of multiple idiopathic root resorption were analyzed retrospectively, and the related literature was reviewed.@*Results@#The patient had no history of orthodontic correction, occlusal trauma, trauma history or other causes of root resorption. Clinical examination revealed full-mouth gingival congestion, redness, a loose texture, and variable degrees of destruction of the alveolar bone. Imaging examination showed that teeth 13, 16, 26, 36, 46 had idiopathic root resorption. The diagnoses were multiple idiopathic root resorption and periodontitis. The pathology tests showed that a large number of osteoclasts were present in the soft tissue surrounding the teeth. Whole-exome sequencing showed that there was a strong correlation between gene mutations (WNT7a and HSPG2) and the present phenotype. Root resorption of teeth without periodontitis was stopped after periodontal treatment during the 19-month follow-up. Tooth 13 was removed, and extraction socket preservation was performed. The etiology of idiopathic root resorption may be related to gene mutations, but it is not clear. At present, there is no effective treatment. @* Conclusion @#Multiple idiopathic root resorption has an unknown etiology, but it may be related to WNT7A and HSPG2 gene mutations. The rate of root resorption can be slowed by controlling periodontal inflammation.

Application progress of alveolar ridge preservation in patients with tooth extracted due to periodontitis / 口腔医学

@#Alveolar ridge preservation (ARP) has developed rapidly as a method for preserving the alveolar socket's bone volume after tooth extraction. ARP can create conditions for implant restoration, and reduce operation difficulties by decreasing alveolar ridge absorption. There are certain difficulties of ARP applicationin patients with tooth extracted due to periodontitis. This paper mainly introduces the characteristics of ARP, compares the similarities and differences among ARP, guided tissue regeneration, guided bone regeneration and immediate implant, and then summarizes their advantages and disadvantages. The paper focuses on the specificity of ARP and the progress of ARP application in patients with tooth extracted due to periodontitis, in order to offer direction for clinical application and future research on ARP.

Preservación Alveolar con Técnica BARP y Provisionalización Inmediata. Caso Clínico

RESUMEN: Actualmente existen varias alternativas para prevenir, disminuir y corregir deformidades en el reborde alveolar, originadas por la reabsorción ósea al momento de la extracción de uno o varios dientes. La preservación alveolar es cualquier procedimiento que se realiza al momento de una extracción y permite conservar las dimensiones y el contorno del alveolo. Hay diversas técnicas para preservación las cuales están diseñadas para prevenir tanto como sea posible los cambios ocurridos al retirar un órgano dentario. El tratamiento de elección para reemplazar la funcionalidad, estabilidad biológica y estética de un diente, es a través de la colocación de implantes dentales, cuya colocación posterior a la preservación alveolar reduce los cambios dimensionales del reborde alveolar. La recientemente propuesta técnica de preservación alveolar BARP, "Biologically-oriented Alveolar Ridge Preservation" por sus siglas en Inglés, logró preservar las dimensiones de la cresta alveolar, al tiempo que restringe cualquier interferencia sobre el biomaterial.

ABSTRACT: Nowadays there are several choices, to prevent, reduce and correct alveolar ridge deformities caused by resorption at the time of extracting one or several teeth. Alveolar ridge preservation is defined as any procedure performed, following any dental extraction that allows the dimensions of the alveolus to be preserved. Those techniques of alveolar ridge preservation are designed to prevent as many reabsorption changes that occur after dental extraction. The best choice to replace the functionality, biological stability, and esthetic, of natural teeth is to place a dental implant. The placement of the alveolar ridge preservation treatment reduces the dimensional changes over the alveolar ridge. The recently proposed technique to alveolar ridge preservation called BARP or "Biologically-oriented Alveolar Ridge Preservation" managed to preserve the alveolar ridge dimensions while restricting any interference with the biomaterial at the same time.

Demineralized human dentin matrix for alveolar ridge preservation using a volumetric and histologic analyses in rats

Abstract The aim of this study was to evaluate a Demineralized Human Dentine Matrix (DHDM) as viable biomaterial for alveolar ridge preservation in a rat model. Wistar rats were submitted to the extraction of maxillary first molars bilaterally. Sockets were filled with biomaterials and divided into 4 experimental groups (n=5): blood clot, autogenous bone, bovine-derived xenograft (BDX) and DHDM. Animals were sacrificed at 7, 14 e 28 days. Microtomography (uCT) volumetric evaluation and qualitative histological analyses were performed. Results obtained through the uCT showed similar values between the DHDM and the other experimental groups. The histological evaluation demonstrated DHDM with an unspecific inflammatory process and bone neoformation with slow reabsorption of the material. This result indicates that DHDM implanted in rat sockets is biocompatible and reduces the alveolar ridge volume loss after tooth extraction.

Resumo O objetivo deste estudo foi avaliar a Matriz Dentinária Humana Desmineralizada (MDHD) como biomaterial viável para preservação do rebordo alveolar, no modelo em rato. Ratos Wistar foram submetidos à exodontias dos primeiros molares superiores bilateralmente. Os alvéolos foram preenchidos com biomateriais e divididos em 4 grupos experimentais (n=5): coágulo sanguíneo, osso autógeno, osso xenógeno de origem bovina e MDHD. Os animais foram sacrificados aos 7, 14 e 28 dias. Foram realizadas avaliações volumétricas por microtomografia (uCT) e análises histológicas qualitativas. Os resultados obtidos por meio do uCT mostraram valores semelhantes entre o MDHD e os demais grupos experimentais. A avaliação histológica demonstrou MDHD com processo inflamatório inespecífico e neoformação óssea com lenta reabsorção do material. Esse resultado indica que a MDHD implantada em alvéolo de rato é biocompatível e reduz a perda de volume do rebordo alveolar após extração dentária.

Alveolar Ridge Preservation after Tooth Extraction and Replacement with Fibre reinforced Composite Bridge in a Young Patient: A Case Report

ABSTRACT@#Alveolar ridge preservation is a surgical procedure aimed to preserve the alveolar bone after tooth extraction to eliminate or reduce the need for bone augmentation during implant placement. It includes the use of membrane that is either being used alone or in combination with a bone replacement graft. This case report describes the technique of alveolar ridge preservation after tooth extraction using a xenogenic bone graft combined with a resorbable collagen membrane, and the fabrication of an anterior fibre-reinforced composite (FRC) bridge in an 18-year-old male patient. This treatment allows him to have a good preservation of the volume and architecture of the alveolar ridge as well as soft tissues and temporarily replace a missing anterior tooth until a definitive restoration can be achieved.

Immunohistochemical Analysis of Alveolar Bone Preserved with Autologous Teeth Graft. Osteopontin Expression and its Regulatory Functions in Preserved Alveolar Ridge

ABSTRACT: The present study investigated the healing response of 12 fresh post-extraction alveolous grafted with particulate autologous teeth to achieve preservation of the post-extraction alveolar ridge. The objective is to elucidate the osteoconductive and osteoinductive properties of the autologous dental graft used as a bone substitute in the alveolar ridge preservation technique. Five patients were included, with at least one hopeless tooth and in need of extraction and preservatio n of the ridge, to receive in the same place a dental implant in prosthetic replacement. In the first surgical stage, dental extractions and preservation of the alveolar ridge were performed, using the teeth extracted and processed with an automatic system as bone substitutes. In the second surgical stage, an incisional bone biopsy was performed in each grafted site, the bone beds were recapitulated in a drilling protocol that allowed the placement of the dental implant, and the harvested bone specimens were prepared for analysis. The histological results of the bone biopsies in all cases showed remnant particles of the dental graft, made up of dentin, partially resorbed, with irregular superficial edges and in close contact with newly forme d bone in transition to mature lamellar bone, in which well differentiated osteocytes were observed. The immunohistochemical results showed a moderate positive expression of osteopontin at the edges of the integrated teeth particles, inside the peritubular dentin space and at the osteodental contact interfaces. In conclusion, the evidence from the study shows that the autologous dental graft is a biocompatible bone substitute, that provides an osteoconductive scaffold that promotes bone cell adhesion and migration for local osteogenesis and that it is associated with moderate in situ expression of osteopontin, which showed a high affinity with mineralized dental tissue, suggesting osteoinductive properties in situ.

RESUMEN: El presente estudio investigó el resultado cicatrizal de 12 alvéolos frescos postextracción injertados con dientes autólogos particulados para lograr la preservación del reborde alveolar postextracción. El objetivo es dilucidar las propiedades osteoconductivas y osteoinductivas del injerto dental autólogo utilizado como sustituto óseo en la técnica de preservación de reborde. Se incluyeron 5 pacientes, con al menos un diente sin esperanza y con necesidad de extracción y preservación del reborde, para recibir en el mismo sitio un implante dental en sustitución protésica. En la primera etapa quirúrgica, se realizaron las extracciones dentales y la preservación del reborde alveolar, utilizando como sustituto óseo los dientes extraídos y procesados con un sistema automático. En la segunda etapa quirúrgica, se realizó una biopsia ósea incisional en cada sitio injertado, los lechos óseos fueron recapitulados en un protocolo de fresado que permitió la colocación del implante dental y los especímenes óseos recolectados fueron preparados para su análisis. Los resultados histológicos de las biopsias óseas en todos los casos mostraron partículas remanentes del injerto dental, conformadas por dentina, parcialmente reabsorbidas, con margenes superficiales irregulares y en estrecho contacto con depósitos de hueso de reciente formación en transición hacia hueso laminar maduro, en el cual se observaron osteocitos bien diferenciados. Los resultados inmunohistoquímicos mostraron una expresión positiva moderada de osteopontina en los bordes de las partículas del injerto dental integrado, al interior del espacio peritubular dentinario y en las interfases de contacto osteodental. En conclusión, la evidencia del estudio muestra que el injerto dental autólogo es un sustituto óseo biocompatible, que provee un andamio osteoconductivo promotor de la adhesión y migración de las células óseas para la osteogénesis local y que está asociado a la expresión modera in situ de osteopontina, la cual mostro una alta afinidad con el tejido dental mineralizado, sugiriendo propiedades osteoinductivas in situ.

Meta-analysis of the effect of platelet-rich fibrin in alveolar ridge preservation / 口腔疾病防治

Objective @#To evaluate the effect of platelet-rich fibrin (PRF) on alveolar ridge preservation after tooth extraction.@*Methods@#Randomized controlled trials (RCTs) published before August 25, 2020 about the use of PRF after tooth extraction were searched through the PubMed, Embase, Cochrane Library, HowNet, Wanfang, CBM databases and clinical trial registration centers in China and the United States. Outcome indicators included in the studies included dry socket occurrence, alveolar bone resorption in the horizontal and vertical directions, and the percentage of new bone. Meta-analysis was conducted with Review Manager Version 5.3 software.@*Results@# A total of 706 studies were retrieved. After screening, 8 studies were analyzed quantitatively. Meta-analysis results showed that PRF could reduce the absorption of alveolar bone after tooth extraction, which reduced the horizontal bone mass (WMD=-0.71, 95% CI=-1.11 to -0.32, P < 0.05) and buccal (WMD=-1.38, 95% CI =-1.87 to -0.88, P < 0.05) and lingual sides (WMD=-0.49, 95% CI=-0.92 to -0.06, P < 0.05) and increased the percentage of new bone (SMD=1.24, 95% CI =0.25 to 2.23, P < 0.05). However, there was no significant difference in preventing the occurrence of dry socket (RD < 0.01, 95% CI=-0.05 to 0.04, P=0.95) and reducing bone absorption in the vertical direction of mesial (WMD=-0.11, 95% CI=-1.17 to 0.95, P=0.84) and distal (WMD=-0.66, 95% CI=-1.93 to 0.60, P=0.30) alveolar ridge after tooth extraction. @*Conclusion @# Using PRF alone after tooth extraction can effectively preserve bone mass in the horizontal direction of the alveolar ridge and the vertical direction of the buccal and lingual sides.

Prosthetically driven alveolar reconstructions: a retrospective study

Abstract This study aims to evaluate the post-extraction alveolar bone reconstruction amongst 12 patients exhibiting loss of buccal bone plate in a tooth of the anterior region of the maxilla using the prosthetically-driven alveolar reconstruction technique (PDAR). In PDAR, a partial fixed provisional prosthesis (PFPP [conventional or adhesive]) with a specially designed pontic maintains the clot in a mechanically stable position during alveolar regeneration. Moreover, the pontic design, in hourglass shape and located in the subgingival area, also prevents gingival margins from collapsing. Gingival recession was evaluated through the 6-month healing period. Cone beam computed tomography (CBCT) was performed 1 month before and 8 months after PDAR treatment. For the primary outcome, in the panoramic imaging, the central area of bone defect in each tooth was selected for linear measurements. Measurements of the vertical buccal bone gain and the gain in thickness in the alveolar bone crest were obtained 8 months after PDAR. Descriptive statistics and intraclass correlation coefficient analysis were conducted. After treatment, all patients showed bone formation (a mean vertical gain of 7.1±3.7 mm, associated with a horizontal mean gain of 4.5±1.4 mm in the alveolar bone crest). The intraclass correlation coefficient for the measurements performed using CBCT was 0.999. No gingival recession, greater than 1 mm, was observed. Lower-morbidity procedures without the use of biomaterials may be a useful in post-extraction alveolar ridge regeneration and/or preservation. PDAR promoted alveolar bone formation without flaps, grafts and membranes.

Resumo Este estudo teve como objetivo avaliar a reconstrução do osso alveolar após extração em 12 pacientes com perda da tábua óssea vestibular em dentes na região anterior da maxila usando a técnica da reconstrução alveolar proteticamente guiada (RAPG). Na RAPG, uma prótese parcial fixa provisória (PPFP [convencional ou adesiva]) com um pôntico com design específico mantém o coágulo numa posição mecanicamente estável. Além disso, o design do pôntico, com formato de ampulheta e localizado na área subgengival, também previne o colapso das margens gengivais. A recessão gengival foi avaliada durante o período de cicatrização de 6 meses. Tomografias computadorizadas cone beam (TCCB) foram feitas 1 mês antes e 8 meses após o tratamento com a RAPG. Para o desfecho primário, nas imagens panorâmicas, a área central do defeito ósseo em cada dente foi selecionada para as medições lineares. As medições do ganho vertical ósseo vestibular e do ganho em espessura na crista óssea alveolar foram realizadas. A análise estística descritiva e a análise do coeficiente de correlação intraclasse forma realizados. Após o tratamento, todos os pacientes apresentaram formação óssea (ganho vertical médio de 7,1±3,7 mm, associado a ganho horizontal médio de 4,5±1,4 mm na crista óssea alveolar). O coeficiente de correlação intraclasse foi de 0,999. Nenhuma retração gengival acima de 1 mm foi observada. Procedimentos com baixa morbidade sem o uso de biomateriais podem ser úteis na regeneração/preservação do rebordo após as extrações. A RAPG promove a formação do osso alveolar sem o uso de retalhos, enxertos e membranas.

Clinical effect of platelet-rich fibrin combined with bone substitute in alveolar ridge preservation / 口腔疾病防治

Objective@#To study the clinical outcomes of implanting platelet rich fibrinogen (PRF) mixed with Bio-Oss® in the extraction socket for alveolar ridge preservation and to provide evidence for clinical application. @*Methods@#Thirty-six patients who underwent alveolar ridge preservation were enrolled. Thirty-six extraction sites were divided into two groups: PRF mixed with Bio-Oss® group (test group) and Bio-Oss® alone (control group). Bone dimensional changes in height and width were measured by CBCT before and 6 months after surgery, and early soft tissue healing and postoperative pain sensation were evaluated clinically 1 week after surgery.@* Results @# There was no significant difference in the alveolar bone height (-1.48 ± 0.40) mm between the test group and the control group. The difference in the alveolar bone width between the test group (-1.09 ± 0.42) mm and the control group (-1.35 ± 0.22) mm was statistically significant (z=-2.63, P=0.01). The postoperative pain score of the test group was 2.39 ± 1.20, and that of the control group was 3.39 ± 1.65, the difference was statistically significant (t=-2.083, P=0.045). There was no significant difference in soft tissue healing between the test group and the control group.@*Conclusion @#The use of PRF mixed with Bio-Oss ®in the alveolar ridge preservation procedure can reduce alveolar bone absorption and postoperative pain.

Recent research advances on alveolar ridge preservation after tooth extraction / 华西口腔医学杂志

Resorption of alveolar bone that occurs following tooth extraction is irreversible, it may compromise the restoration of implants or conventional prostheses. Ridge preservation can minimize ridge resorption after tooth extraction. In this article, healing features of socket after tooth extraction, factors influencing ridge remodeling, and the use of bioma-terials were reviewed.

Early changes of interproximal ridge height with alveolar ridge preservation of maxillary single anterior teeth / 华西口腔医学杂志

OBJECTIVE@#This study aimed to provide foundation for interproximal bone preservation to improve esthetic effects of inter-implant papillar by alveolar ridge preservation following tooth extraction of maxillary single anterior teeth.@*METHODS@#A total of 30 patients requiring maxillary single anterior teeth extraction were randomly divided into test and control groups (15 cases in each group). The test group underwent alveolar ridge preservation after tooth extraction (Bio-Oss bone powder was implanted in alveolar fossa and fixed with surface free gingival graft suture). No other treatment was performed on the control group after tooth extraction. All patients were scanned using cone beam computed tomography with personalized digital radiographic template at 7 days and 6 months after tooth extraction. Then, measurement of height changes at the interproximal and middle buccal was performed.@*RESULTS@#At the mesial and distal interproximal site, ridge height reduction in the test group measured (0.358±0.151) mm, (0.322±0.180) mm, whereas that of control group reached (0.653±0.260) mm, (0.667±0.274) mm, indicating statistical significance (P<0.05). At the middle buccal site, the ridge height reduction of test group amounted to (0.826±0.307) mm, whereas that of control group totaled (1.510±0.625) mm, also presenting statistical significance (P<0.05).@*CONCLUSIONS@#Alveolar ridge preservation can reduce absorption of alveolar crest height after tooth extraction, which could improve esthetic effects of inter-implant papillae gingiva.

Comparison of Bone grafts for Alveolar ridge dimensional preservation

Introduction: The aim of this study was to assess the prevalence of suicidal ideation, suicidal attempts, andloneliness among dental and medical students in the western region of Saudi Arabia. Materials and Methods:This cross-sectional study investigated 607 dental and medical students and interns in private colleges in SaudiArabia. A self-administrated questionnaire was based on the Revised UCLA Loneliness Scale. Suicidal ideationand attempts were measured by a questionnaire adopted from previous research. The data was collected at theend of the year at examination time. Results: The loneliness mean was M= 45.14 (SD 8.66). Among theparticipants, 37.7% had experienced suicidal ideation throughout their lives, 33.4% had experienced suicidalideation during the previous 12 months, and 23.2% had attempted suicide. Loneliness was significantly relatedwith suicidal ideation during the previous 12 months (p <0.001) and with suicidal attempts (p = 0.005). Theresults showed that the following subgroups had higher risk for suicidal ideation and suicidal attempts: female,low family income, married, and dental students. Conclusion: The high levels of suicidal ideation and attemptsamong dental and medical students in the western region of Saudi Arabia call for the implementation ofprofessional counselling and health promotion programs.

The research progress in gingival invagination / 中华口腔医学杂志

Gingival invagination is a type of gingival cleft that occurs during orthodontic space closure in some of the orthodontic patients who received tooth extraction. Clinical manifestations may be fine folds in attached gingiva surface, or deep cleft that penetrates the interdental papilla from the buccal to the lingual alveolar process. Gingival invagination can affect the health of local periodontal tissues, the effect and stability of orthodontic treatment. This article reviews the research progress of gingival invagination studies, including the definition, manifestations, causes, influencing factors and effects.

Coralline hydroxyapatite for ridge preservation in the maxillary anterior zone:A cone beam CT analysis / 医学研究生学报

Objective Coralline hydroxyapatite (CHA),in comparison with Bio-Oss bone meal,is a material with extensive resources but no immunogenicity or risk of disease-transmission. The aim of this article was to study the clinical application of CHA in ridge preservation in the maxillary anterior zone. Methods Twenty-six patients underwent extraction of maxillary anterior teeth (n=26) for chronic periodontitis or periapical periodontitis. The patients were randomly assigned into a CHA and a control group of equal number to receive ridge preservation with CHA and Bio-Oss bone meal respectively. Cone beam computed tomography (CBCT) was performed immediately and at 4 months after ridge preservation to compare the vertical and horizontal alterations of the alveolar ridge be-tween the two groups of patients. Results After ridge preservation,both the CHA and control groups showed a reduction in the width ([1.1±0.7] vs [1.3±1.9] mm) and height of the alveolar ridge ([1.3±1.6] vs [1.2±1.4] mm),but with no statistically significant differences between the two groups (P<0.05). Conclusion For ridge preservation in the maxillary anterior zone,CHA has a similar effect to that of Bio-Oss bone meal and therefore is an ideal material for bone graft.

Comparison of Bio-degradation for Ridge Preservation Using Silk Fibroin-based Grafts and a Collagen Plug

A material for ridge preservation should have dimensional stability to resist bio-degradation. This study was designed to compare bio-degradation of ridge preservation materials. Collagen plug was used as a positive control. Untreated, ethanol-treated, and 4-hexylresorcinol (4HR)-treated silk plugs were used for the experimental group. Each material underwent a scanning electron microscopic exam and a Fourier transform infrared (FT-IR) spectroscopic exam. Bio-degradation was evaluated by analyzing cylindrical bony defects in rabbit tibias. There were no prominent differences in microstructure among the silk plug groups. FT-IR exam demonstrated that the ethanol- and 4HR-treated silk plug groups had enhanced β-sheet structure. All silk plug groups exhibited significantly higher residual graft than the collagen plug group 4 weeks postoperative (p<0.05). In conclusion, silk fibroin-based ridge preservation material was less bio-degradable than a collagen plug until at least 4 weeks after grafting.

Dimensional changes of hard and soft tissues in post-extraction sites: evaluation of two biomaterials / Cambios dimensionales de los tejidos duros y blandos en sitios post-exodoncia: evaluación de dos biomateriales

ABSTRACT Introduction: the techniques for alveolar ridge preservation with different biomaterials show better healing processes and modify the patterns of alveolar bone resorption. The goal of this study was to evaluate the clinical, radiographic, and histological changes of tissues in post-extraction sites after 90 and 180 days by using two biomaterials for alveolar ridge preservation. Materials: descriptive study involving the extraction of twenty-seven uni- and biradicular teeth comparing two biomaterials randomly distributed. Group A received resorbable synthetic hydroxyapatite (OsseoU) and Group B received mineralized freeze-dried allogeneic bone (Tissue Bank®). Quantitative and qualitative measurements were made 180 days post-extraction. The statistical analysis was conducted with the Shapiro-Wilks, Levine, and Student t tests. Results: comparing the two biomaterials on day 180 yielded no statistically significant differences in terms of the "height" variable. The "width" variable yields a p = 0.010 value, suggesting statistically significant differences, since Group A is 0.789 ± 0.276 times better (3.72 ± 0.76) than group B (2.93 ± 0.55). The radiographic evaluation did not yield differences between both groups (p = 0.711). Conclusion: this study shows the dimensional changes of post-extraction sites in both groups, with a clinical difference in ridge width, and no radiographic or histological differences, neither statistically significant changes in terms of alveolar ridge height. Resorbable synthetic hydroxyapatite (OsseoU) is then a biomaterial as effective as mineralized freeze-dried allogeneic bone (Tissue Bank®).

RESUMEN. Introducción: las técnicas de preservación del reborde alveolar con diferentes biomateriales demuestran un mejor proceso de cicatrización que si no se lleva a cabo ningún procedimiento y modifican los patrones de reabsorción del hueso alveolar. El objetivo del presente estudio consistió en evaluar los cambios clínicos, radiográficos e histológicos de los tejidos en sitios post-exodoncia a los 90 y 180 días, utilizando dos biomateriales para la preservación del reborde. Materiales: estudio descriptivo en el que se hacen las exodoncias de veintisiete dientes uni- y birradiculares y se comparan dos biomateriales diferentes repartidos aleatoriamente. El grupo A recibió hidroxiapatita sintética reabsorbible (OsseoU) y el grupo B recibió hueso alogénico mineralizado, secado por congelación (Tissue Bank®). Se hicieron mediciones cuantitativas y cualitativas a los 180 días. El análisis estadístico se realizó con pruebas de Shapiro-Wilks, Levine y t-Student. Resultados: al comparar los dos biomateriales a los 180 días, se observa que en la variable "altura" no existen diferencias estadísticamente significativas. En la variable "amplitud" se establece un valor p = 0,010, lo cual indica que hay diferencias estadísticamente significativas, siendo 0,789 ± 0,276 mejor el grupo A (3,72 ± 0,76) comparado con el grupo B (2,93 ± 0,55). En la evaluación radiográfica no se reportan diferencias entre los dos grupos (p = 0,711). Conclusión: este estudio demuestra cambios dimensionales de los sitios post-exodoncia en ambos grupos, con diferencia clínica en la amplitud de reborde, y sin diferencias radiográficas ni histológicas, ni cambios estadísticamente significativos en cuanto a la altura del reborde. La hidroxiapatita sintética reabsorbible (OsseoU) es entonces un biomaterial igual de efectivo que el hueso alogénico mineralizado, secado por congelación (Tissue Bank®). Palabras claves: técnicas de preservación de reborde, hidroxiapatita sintética, hueso alogénico mineralizado, secado por congelación.

Evaluation with different measuring methods for the alveolar bone change of ridge preservation in molar sites / 北京大学学报(医学版)

Objective:To investigate the changes of the vertical height and width of the alveolar bone six months after the alveolar ridge preservation in periodontal compromised molar sites of severe alveolar bone defects with clinical direct measurement,parallel periapical radiographs,and cone-beam computed tomography (CBCT),and to analyze the effect of the three different methods of measurement.Methods:In this study,20 subjects requiring tooth extraction on account of periodontal disease with a total of 23 ex-tracted molars were enrolled.Extractions were performed atraumatically and patients were received alveo-lar ridge preservation procedure with Bio-Ossand Bio-Gide.Clinical direct measurements were taken after tooth extraction and during the implant surgery 6 months later,CBCT scans and parallel periapical radiographs were taken immediately after ridge preservation and 6 months later.The changes of alveolar ridge width and vertical height after six months were measured and analyzed through the above-mentioned three methods and the similarities and differences of the measured effect were compared.Results:There were no significant difference of alveolar vertical height in the center of the extraction sites,the center of distal aspect,and distobuccal aspect between the clinical direct measurements and the CBCT measure-ments (P>0.05),alveolar vertical height in other points and alveolar width measurements were statical-ly significant (P cally significant (P>0.05).The change of the alveolar height in the center of the extraction socket after six months measured by parallel periapical was (5.84 ±4.28)mm,which was closed to the clinical di-rect measurement and the CBCT measurement.Conclusion:Clinical direct measurement and CBCT measurement were largely consistent in the evaluation of the alveolar bone height and width after the alveolar ridge preservation using deproteinized boving bone mineral (DBBM,Bio-Oss)and bioabsor-bable collagen membrane (Bio-Gide)in periodontal compromised molar sites of severe bone defects.

A novel technique to preserve the alveolar ridge width following tooth extraction in the maxillary frontal area / 北京大学学报(医学版)

Objective:To introduce a novel ridge preservation technique with micro-titanium plate avoiding the use of bone grafting materials,and evaluate the potential horizontal bone preservation effect of this new technique,applied on single maxillary central incisors after tooth extraction for future implant restoration.Methods:Nine patients (six women and three men),mean age (26.0 ±5.7)years(from 1 8 to 34 years)referred to the Department of Oral Implantology,Peking University School and Hospital of Stomotology,were selected and diagnosed with unsalvageable single middle incisor with fine general con-ditions,no signs of acute local inflammation,no ongoing or previous periodontitis,healthy neighboring teeth and intact buccal bone walls.Tooth extraction,delayed implant placement and implant-supported single crown restoration were selected as treatment plan.The teeth were extracted atraumatically with lo-cal anesthesia,followed by a reflection of a minor flap to exposed 2-3 mm of the buccal bone plate.Af-ter that,a micro-titanium plate was trimmed and bended to fit the convexity of the labial bone and fixed by two mini pins with intent to support the labial soft tissue.The flap was then repositioned over the micro titanium plate and secured with two single sutures.No bone grafting materials or releasing incisions were needed.The sockets were left to heal without any intention of primary wound closure.Cone-beam compu-ted tomographic (CBCT)scans were obtained before and four months after tooth extraction.Horizontal ridge widths were measured with CBCT software,and the preservation effects were calculated and recor-ded by the percentage of horizontal ridge alteration.Results:The nine extraction sockets were healed un-eventfully.The average socket width before extraction was (7.51 ±0.48)mm (6.92-7.82 mm).The average alveolar ridge labial-palatal width at the control point of the edentulous area was (6.81 ±0.44) mm (6.04-7.38 mm)4 months after tooth extraction,the mean percentage of ridge width preserved was 90.87%±2.91%(87.28%-95.60%).Conclusion:This novel ridge preservation method by the usage of a micro-titanium plate did not interfere with the natural socket healing process,and at the same time,largely preserved the width of alveolar ridge without any bone grafting procedures.Long term results remain to be seen.