The alveolar process following single-tooth extraction: a study of maxillary incisor and premolar sites in man.

OBJECTIVE: The present investigation was performed to determine some dimensional alterations that occur in the alveolar process of the incisor and premolar sites of the maxilla following tooth removal. MATERIAL AND METHODS: Computer-assisted cone-beam computed tomography (CBCT) scans were obtained from the maxilla using an iCAT unit, and involved edentulous and contralateral tooth sites. For each site included in the study, parasagittal and axial reconstructions, 1 mm apart, were made and measurements of different variables (cross-sectional area, height, and width) performed. RESULTS: The study involved 69 subjects and disclosed that the cross-sectional area and the height and width of the alveolar process of the lateral incisor site were the smallest and those of the second premolar the largest. All parameters had been significantly reduced after the completion of the ≥1 year of healing. Thus, the overall (i) cross-sectional area was reduced from 99.1 to 65.0 mm(2) , (ii) the height from 11.5 to 9.5 mm, and (iii) the width from 8.5 to 3.2 mm (marginal 1/3(rd) ), 8.9 to 4.8 mm (middle portion), and 9.0 to 5.7 mm (apical portion). CONCLUSION: The removal of single tooth caused marked hard tissue diminution. The loss of hard tissue was most pronounced in the buccal and marginal portions of the edentulous ridge that in most sites had acquired a triangular shape.

Alveolar socket healing: what can we learn?

Tooth extraction induces a series of complex and integrated local changes within the investing hard and soft tissues. These local alterations arise in order to close the socket wound and to restore tissue homeostasis, and are referred to as '"socket healing". The aims of the present report were twofold: first, to describe the socket-healing process; and, second, to discuss what can be learned from the temporal sequence of healing events, in order to improve treatment outcomes. The socket-healing process may be divided into three sequential, and frequently overlapping, phases: inflammatory; proliferative; and modeling/remodeling. Several clinical and experimental studies have demonstrated that the socket-healing process promotes up to 50% reduction of the original ridge width, greater bone resorption at the buccal aspect than at the lingual/palatal counterpart and a larger amount of alveolar bone reduction in the molar region. In conclusion, tooth extraction, once a simple and straightforward surgical procedure, should be performed in the knowledge that ridge reduction will follow and that further clinical steps should be considered to compensate for this, when considering future options for tooth replacement.

The Basal Bone and Alveolar Process in the Maxillary Anterior Region in Humans: A Cone Beam Computed Tomographic Study.

The aim of this study was to describe the basal bone and alveolar process in the maxillary anterior region by assessing patient CBCT scans. Parasagittal reconstructions were made to quantify basal bone and alveolar process dimensions and inclination of teeth in the maxillary anterior region. The CBCT scans of 87 patients and 522 tooth sites were included in this study. The results showed that the surface areas of the basal bone, alveolar process, and palatal triangle varied from 22.1 to 54.1 mm2, 87.8 to 144.0 mm2, and 37.1 to 66.0 mm2, respectively. The basal bone in the canine region had a significantly smaller cross-sectional area than in the incisor region. The alveolar process in the canine region was markedly larger than those of the central and lateral incisor regions. The mean overall thickness of the alveolar facial bone at 3, 5, and 7 mm above the CEJ were 0.6 ± 0.5 mm, 0.9 ± 0.5 mm, and 0.7 ± 0.6 mm, respectively. Additionally, the findings demonstrated that the cross-sectional area of the alveolar process and palatal triangle were greater among men than women. The study identified significant anatomical differences among various tooth regions in the anterior maxilla. The results also demonstrated that the tooth type, but not the tooth inclination or apex location, correlates with the size of the alveolar process.

Periodontal ligament-derived mesenchymal stem cells modulate neutrophil responses via paracrine mechanisms.

BACKGROUND: Mesenchymal stem cells differentiate into distinct mesenchymal cell lineages and regulate the immune response. The aim of this study was to determine whether periodontal ligament-derived mesenchymal stem cells (PDLSCs) have the ability to modulate neutrophil responses via paracrine mechanisms. METHODS: CD105-enriched PDLSCs were seeded for 24 h and challenged with Porphyromonas gingivalis total protein extract (PgPE) (0 or 2 ug/mL) for 3 h. Cells were then washed and further cultured for 18 h and the supernatants were collected and stored. Next, neutrophil-differentiated human promyelocytic leukemia HL-60 cells (HL60D) were treated with PDLSCs supernatants and HL-60D activation and functional responses were determined. RESULTS: PgPE treatment induced higher secretion of inflammatory markers and chemokines by PDLSCs, including RANTES, eotaxin, interferon (IFN)-γ- inducible protein 10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), IFN-γ, interleukin (IL)-6, IL-8 and IL-1ra (P < 0.05). HL-60D recruitment rate was increased by 4.7 ± 1.09-fold when exposed to PgPE-treated PDLSCs supernatants. PgPE-treated PDLSCs supernatants promoted a 1.78 ± 1.04-fold increase in the production of intracellular reactive oxygen species (ROS) by PMA-stimulated HL-60D, whereas PgPE-untreated PDLSCs supernatants led to a 16% reduction in intracellular ROS. In sharp contrast, neither PgPE-untreated nor PgPE-treated PDLSCs supernatants altered tumor necrosis factor (TNF)-α and IL-1ß secretion by HL-60D cells. CONCLUSION: Together, these findings suggest an important role of PDLSCs in the recognition of P. gingivalis, paracrine recruitment and activation of antimicrobial mechanisms in innate immune cells, without interfering in cytokine responses.

A systematic review and meta-analysis of the survival rate of implants placed in previously failed sites.

The aim of this study was to conduct a systematic review and meta-analysis to assess the clinical outcomes of dental implants placed in previously early and late implant failed sites. An electronic literature search was conducted in several databases for articles published up to February 2018. Human clinical trials that received at least one implant in a previously failed site were included. Hence, the PICO question that was aimed to be addressed was: Do patients undergoing implant replacement (second and third attempts) in previous failed sites have survival rates similar to implants placed at first attempts? A random effects model was used to calculate survival weighted means and corresponding 95% Confidence Intervals (CI) among studies. Eleven studies of low to moderate methodological quality were included in this review. Implants placed in sites with history of one and two implant failures had a weighted survival rate (SR) of 88.7% (95%CI 81.7-93.3) and 67.1% (95%CI 51.1-79.9), respectively. Implants placed in sites with a previous early failure revealed a weighted SR of 91.8% (95%CI 85.1-95.6). First implants presented higher SR than implants placed in sites with one or two previous implant failures. In contrast, implants placed in sites with one and two implant failures had similar SR. Within its limitations, this review suggests that replacement implants have moderate SR. Larger prospective studies with well-defined criteria for early and late implant failure are necessary to confirm and expand on these results.

A systematic review and meta-analysis of the survival rate of implants placed in previously failed sites

Abstract The aim of this study was to conduct a systematic review and meta-analysis to assess the clinical outcomes of dental implants placed in previously early and late implant failed sites. An electronic literature search was conducted in several databases for articles published up to February 2018. Human clinical trials that received at least one implant in a previously failed site were included. Hence, the PICO question that was aimed to be addressed was: Do patients undergoing implant replacement (second and third attempts) in previous failed sites have survival rates similar to implants placed at first attempts? A random effects model was used to calculate survival weighted means and corresponding 95% Confidence Intervals (CI) among studies. Eleven studies of low to moderate methodological quality were included in this review. Implants placed in sites with history of one and two implant failures had a weighted survival rate (SR) of 88.7% (95%CI 81.7-93.3) and 67.1% (95%CI 51.1-79.9), respectively. Implants placed in sites with a previous early failure revealed a weighted SR of 91.8% (95%CI 85.1-95.6). First implants presented higher SR than implants placed in sites with one or two previous implant failures. In contrast, implants placed in sites with one and two implant failures had similar SR. Within its limitations, this review suggests that replacement implants have moderate SR. Larger prospective studies with well-defined criteria for early and late implant failure are necessary to confirm and expand on these results.

Caracterização do efeito imunomodulatório das células mesenquimais indiferenciadas na resposta inflamatória a Porphyromonas gingivalis / Role of periodontal-derived mesenchymal stem cells in Porphyromonas gingivalis infection

O objetivo deste estudo foi caracterizar as respostas das células mesenquimais indiferenciadas derivadas do ligamento periodontal (PDLSCs) ao extrato proteico total de Porphyromonas gingivalis (PgPE) e avaliar seu impacto nas propriedades biológicas das células leucêmicas promielocíticas humanas HL-60. PDLSCs enriquecidas com CD105 foram semeadas em placas de 6 poços durante 24h. Em seguida, as células foram desafiadas com PgPE (0 e 2 mg/ml) durante 3h (período de exposição). Os sobrenadantes foram então descartados; PDLSCs foram lavadas com PBS e cultivadas por 18h adicionais. Por fim, os sobrenadantes foram coletados. Os níveis de citocinas e quimiocinas nos sobrenadantes foram avaliados por ensaios multiplex. Na sequência, o efeito dos sobrenadantes derivados de PDLSCs (tratadas ou não com PgPE) sobre a ativação, o recrutamento e a resposta inflamatória de HL-60 foi avaliado. PDLSCs responderam ao tratamento com PgPE. RANTES, eotaxina e IP-10 (proteína produzida por IFN-?) foram detectados apenas em sobrenadantes de PDLSCs/PgPE. Além disso, PgPE induziu maior secreção de proteína quimiotática de neutrófilos (MCP)-1, intérferon (IFN)-?, interleucina (IL)-6, IL-8 e IL-1ra (p> 0,05). O recrutamento de HL-60D aumentou 4,7 vezes quando estas células foram expostas a sobrenadantes PDLSCs/PgPE, enquanto que os sobrenadantes de PDLSCs não afetaram a quimiotaxia de HL-60D. Sobrenadantes PDLSCs promoveram uma redução de 16% na produção de espécies de oxigênio reativo (ROS) por HL-60D estimuladas por PMA (p=0,013). Em contraste, sobrenadantes PDLSCs/PgPE promoveram um aumento de 1,78±1,04 vezes (p=0,046) na produção de ROS. Finalmente, tanto sobrenadantes PDLSCs, como sobrenadantes PDLSCs/PgPE, não influenciaram a produção de fator de necrose tumoral (TNF)-? e IL-1? pelas HL-60D em resposta ao lipopolissacarídeo (LPS). Esses achados sugerem um importante papel das PDLSCs no reconhecimento de P. gingivalis, recrutamento de células imunes inatas e ativação de mecanismos antimicrobianos.