Karina Gonzales Silvério Ruiz

Proteomic analysis of human dental cementum and alveolar bone

UNLABELLED Dental cementum (DC) is a bone-like tissue covering the tooth root and responsible for attaching the tooth to the alveolar bone (AB) via the periodontal ligament (PDL). Studies have unsuccessfully tried to identify factors specific to DC versus AB, in an effort to better understand DC development and regeneration. The present study aimed to use matched human DC and AB samples (n=7) to generate their proteomes for comparative analysis. Bone samples were harvested from tooth extraction sites, whereas DC samples were obtained from the apical root portion of extracted third molars. Samples were denatured, followed by protein extraction reduction, alkylation and digestion for analysis by nanoAcquity HPLC system and LTQ-FT Ultra. Data analysis demonstrated that a total of 318 proteins were identified in AB and DC. In addition to shared proteins between these tissues, 105 and 83 proteins exclusive to AB or DC were identified, respectively. This is the first report analyzing the proteomic composition of human DC matrix and identifying putative unique and enriched proteins in comparison to alveolar bone. These findings may provide novel insights into developmental differences between DC and AB, and identify candidate biomarkers that may lead to more efficient and predictable therapies for periodontal regeneration. BIOLOGICAL SIGNIFICANCE Periodontal disease is a highly prevalent disease affecting the world population, which involves breakdown of the tooth supporting tissues, the periodontal ligament, alveolar bone, and dental cementum. The lack of knowledge on specific factors that differentiate alveolar bone and dental cementum limits the development of more efficient and predictable reconstructive therapies. In order to better understand cementum development and potentially identify factors to improve therapeutic outcomes, we took the unique approach of using matched patient samples of dental cementum and alveolar bone to generate and compare a proteome list for each tissue. A potential biomarker for dental cementum was identified, superoxide dismutase 3 (SOD3), which is found in cementum and cementum-associated cells in mouse, pig, and human tissues. These findings may provide novel insights into developmental differences between alveolar bone and dental cementum, and represent the basis for improved and more predictable therapies.

Periosteum-Derived Cells as an Alternative to Bone Marrow Cells for Bone Tissue Engineering Around Dental Implants. A Histomorphometric Study in Beagle Dogs

BACKGROUND The aim of this study is to investigate the potential use of periosteum-derived cells (PCs) for tissue engineering in peri-implant defects. METHODS Bone marrow cells (BMCs) and PCs were harvested from seven adult beagle dogs, cultured in vitro, and phenotypically characterized with regard to their osteogenic properties. The animals were then subjected to teeth extraction, and 3 months later, two implant sites were drilled, bone dehiscences created, and dental implants placed. Dehiscences were randomly assigned to one of two groups: PCs (PCs + carrier) and BMCs (BMCs + carrier). After 3 months, the animals were sacrificed and the implants with adjacent hard tissues were processed for undecalcified sections. Bone-to-implant contact, bone fill within the limits of implant threads, and new bone area in a zone lateral to the implant were histometrically obtained. RESULTS In vitro, phenotypic characterization demonstrated that both cell populations presented osteogenic potential, as identified by the mineral nodule formation and the expression of bone markers. Histometrically, an intergroup analysis showed that both cell-treated defects had similar bone fill within the limits of implant threads and bone-to-implant contact (P >0.05), and although a trend toward higher new bone area values was found for the PC group, there was no significant difference between the experimental groups (P >0.05). CONCLUSIONS Periosteal and bone marrow cells presented a similar potential for bone reconstruction. As such, periosteum may be considered as an alternative source of osteogenic cells in implant dentistry.

Cigarette smoke inhalation modulates gene expression in sites of bone healing: a study in rats

OBJECTIVE The aim of this study was to assess the effect of cigarette smoke inhalation (CSI) on gene expression in alveolar bone healing sites. STUDY DESIGN Wistar rats were randomly assigned to the groups: control [animals not exposed to CSI (n = 20)] and test [animals exposed to CSI, starting 3 days before teeth extraction and maintained until killing them (n = 20)]. First mandibular molars were bilaterally extracted, and the expression of alkaline phosphatase, bone morphogenetic protein (BMP) 2 and 7, receptor activator of nuclear factor κB ligand, osteoprotegerin, and d2 isoform of vacuolar adenosine triphosphatase V(0) domain were assessed by quantitative polymerase chain reaction in the newly formed tissue in the sockets. RESULTS Overall, data analysis demonstrated that CSI significantly affected the expression pattern of all of the studied genes except BMP-7. CONCLUSION The expression of key genes for bone healing may be affected by CSI in tooth extraction sites.

Peri‐implant reconstruction using autologous periosteum‐derived cells and guided bone regeneration

AIM This investigation evaluated the bone healing in peri-implant defects treated with periosteum-derived cells (PCs) and guided bone regeneration (GBR). MATERIAL AND METHODS PCs were harvested from six beagle dogs and characterized in vitro with regard to their osteogenic properties. The animals were subjected to teeth extraction in the mandible, and after 3 months of healing, implant sites were drilled, bone dehiscences were created and implants were placed. Dehiscences were randomly assigned to: PCs+GBR, GBR, PCs and non-treated defects. After 3 months, the implants/adjacent tissues were processed. Bone-to-implant contact (BIC) bone fill (BF) within implant threads, and bone area (BA) in a zone lateral to the implant were obtained. RESULTS In vitro analyses confirmed the osteogenic potential of PCs. Histometrically, no statistically significant differences were observed among the PCs+GBR, GBR and PCs groups for both BF and BIC (p>0.05), whereas these groups showed statistically higher values, as compared with the non-treated group (p<0.05). With respect to BA, the PCs+GBR and GBR groups presented significantly higher means, as compared with the PCs and non-treated groups (p<0.05). CONCLUSION Although successful outcomes have been promoted by using the combined approach, PCs in conjunction with membranes did not provide additional benefit during peri-implant bone regeneration, when compared with the therapeutic approaches used alone.

Xenogenous Collagen Matrix and/or Enamel Matrix Derivative for Treatment of Localized Gingival Recessions: A Randomized Clinical Trial. Part II: Patient-Reported Outcomes

BACKGROUND Considering xenogeneic collagen matrix (CM) and enamel matrix derivative (EMD) characteristics, it is suggested that their combination could promote superior clinical outcomes in root coverage procedures. Thus, the aim of this parallel, double-masked, dual-center, randomized clinical trial is to evaluate clinical outcomes after treatment of localized gingival recession (GR) by a coronally advanced flap (CAF) combined with CM and/or EMD. METHODS Sixty-eight patients presenting one Miller Class I or II GRs were randomly assigned to receive either CAF (n = 17); CAF + CM (n = 17); CAF + EMD (n = 17), or CAF + CM + EMD (n = 17). Recession height, probing depth, clinical attachment level, and keratinized tissue width and thickness were measured at baseline and 90 days and 6 months after surgery. RESULTS The obtained root coverage was 68.04% ± 24.11% for CAF; 87.20% ± 15.01% for CAF + CM; 88.77% ± 20.66% for CAF + EMD; and 91.59% ± 11.08% for CAF + CM + EMD after 6 months. Groups that received biomaterials showed greater values (P <0.05). Complete root coverage (CRC) for CAF + EMD was 70.59%, significantly superior to CAF alone (23.53%); CAF + CM (52.94%), and CAF + CM + EMD (51.47%) (P <0.05). Keratinized tissue thickness gain was significant only in CM-treated groups (P <0.05). CONCLUSIONS The three approaches are superior to CAF alone for root coverage. EMD provides highest levels of CRC; however, the addition of CM increases gingival thickness. The combination approach does not seem justified.

Salivary carriage of periodontal pathogens in generalized aggressive periodontitis families

BACKGROUND Generalized aggressive periodontitis (GAP) is a multifactorial disease that shows a specific microbial profile and a familial aggregation. AIM This study evaluated the salivary microbial profile of families with a history of GAP and compared them with healthy families. DESIGN Fifteen families with parents presenting periodontal health and 15 with parents with a history of GAP were selected. Each family had a child aged 6-12 years. Stimulated saliva was collected from all subjects, and Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), and Aggregatibacter actinomycetemcomitans (Aa) amounts were determined. RESULTS Children of GAP families showed higher detection of Aa (90%) than children of healthy families (45%) (P < 0.05). Parents with GAP showed a Pg salivary concentration statistically higher than that of healthy parents (P < 0.05).Children of GAP families, however, exhibited similar Pg concentration than healthy children (P > 0.05). Tf amounts did not differ either in parents or in children (P > 0.05) The infection risk calculation indicates that children who have one parent who is positive for Aa have 16.3 times (95% CI 3.1-87.2) more risk of being infected with Aa (P < 0.05) than children from an Aa-negative family. CONCLUSION It may be concluded that children of parents with aggressive periodontitis have higher levels and higher risk of Aa infection.

Transcriptome of Healthy Gingival Tissue from Edentulous Sites in Patients with a History of Aggressive Periodontitis

BACKGROUND This study evaluated the transcriptome of healthy gingival tissue from edentulous sites in patients with a history of generalized aggressive periodontitis (GAgP), chronic periodontitis (CP) and in patients with no history of periodontitis (H), using microarray and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis. METHODS Healthy gingival tissue from edentulous sites was taken from GAgP (n =12), CP (n=12) and H (n=12) patients. Initially, total RNA from 4 tissues samples per group was employed in transcriptomic microarray analysis. Differential gene expression (fold-change), gene ontology (GO; biological process) and pathway analyses were performed. Genes that were differentially expressed and showing a significant role on altered pathways were validated by qRT-PCR analysis on 12 samples per group. RESULTS In total, 270 probes sets and 50 GO groups were differentially expressed (up-regulated or down-regulated) between GAgP and H. Natural killer cell receptors and other genes related to the immune system were up-regulated in GAgP, while genes with functions in neural processes and in proliferation/differentiation of keratinocytes were under-expressed. There were 220 probe sets and 75 GO groups that were differentially expressed when comparing CP and GAgP. CP was characterized by the increased expression of genes related to responses to external stimuli and an under-expression of immune system-related genes. qRT-PCR analysis confirmed the microarray results, that KIR2DL4, IL6 and SELE were highly expressed in GAgP than CP or H patients. CONCLUSION This study demonstrates differences in the transcriptome of healthy gingival tissue from edentulous sites from GAgP when compared with that of H or CP patients.

Mesenchymal stem cells in periodontics: new perspectives

A engenharia de tecidos e um campo contemporâneo da ciencia, que visa criar condicoes baseadas em principios de biologia celular e molecular, bioengenharia e biomateriais para regenerar tecidos. As celulas tronco mesenquimais apresentam altas taxas de proliferacao e sao capazes de se diferenciar, sob certas condicoes, em multi-linhagens, sugerindo que elas tem grande potencial para atuar no campo da regeneracao. As celulas tronco derivadas de tecidos dentais sao uma fonte alternativa adequada de celulas mesenquimais uma vez que sao de facil acesso e tem baixa morbidade para o doador. Estudos demonstraram que elas ja foram isoladas e caracterizadas a partir de diversos tecidos tais como polpa dentaria, dentes deciduos esfoliados, ligamento periodontal, gengiva, foliculo dental e papila apical. Entretanto, os estudos demonstram que ha heterogeneidade entre essas populacoes e nao existe um metodo padrao para selecionar as celulas-tronco dentais mais apropriadas para procedimentos regenerativos. O objetivo desta revisao e apresentar o conhecimento atual dos varios tipos de celulas-tronco derivadas de dentes e discutir as novas perspectivas para seu uso na engenharia de tecidos periodontais.