Alveolar bone loss, platelet and glycosylated haemoglobin levels in 239 patients. A clinical study

BACKGROUND: The relation between periodontal disease and systemic pathologies is still not widespread among general practitioners. The aim of our study is to evaluate whether or not periodontal radiological diagnosis can aid the detection of blood alterations associated with acquired systemic diseases. MATERIAL AND METHODS: This is a cross sectional study. All of the participants underwent a panoramic radiograph and a complete blood test. Morphological bone loss was considered as positive in those patients who showed radiographically more than 1 tooth with bone loss greater than or equal to the middle third of the root. The statistical analysis was performed by comparing the variables using the ANOVA or U-Mann-Whitney tests for independent samples with normal conditions. The correlation coefficient was analysed using the Pearson test. RESULTS: 239 patients were included in our study (96 men and 143 women) with an average age of 64.40 years. 59.04% of the patients were determined as morphological bone loss positive and had on average 4 teeth less than negative patients (p < 0.0001). Also the average platelet levels in positive patients were lower (p = 0.024) and mean levels of HBA1c (p = 0.009) were higher. CONCLUSIONS: Morphological bone loss parameter can be useful both for dentists and general practitioners to refer, subsequently, to periodontal specialist

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Cardiovascular and Autonomic Dysfunction in Murine Ligature-Induced Periodontitis.

The present study examined the hemodynamics [arterial pressure (AP), AP variability (APV), heart rate (HR), and heart rate variability (HRV)], cardiac function (echocardiographycally), and myocardial inflammation in Balb/c mice submitted to Periodontitis, through the ligation of the left first molar, or Sham surgical procedure. The first protocol indicated that the AP was similar (136 ± 2 vs. 132 ± 3 mmHg in Sham), while the HR was higher in mice with Periodontitis (475 ± 20 vs. 412 ± 18 bpm in Sham), compared to their Sham counterparts. The APV was higher in mice with Periodontitis when evaluated in the time domain (4.5 ± 0.3 vs. 3.4 ± 0.2 mmHg in Sham), frequency domain (power of the LF band of systolic AP), or through symbolic analysis (patterns 0V + 1V), indicating a sympathetic overactivity. The HRV was similar in the mice with Periodontitis, as compared to their Sham counterparts. In the second protocol, the mice with Periodontitis showed decreased cardiac output (10 ± 0.8 vs. 15 ± 1.4 mL/min in Sham) and ejection fraction (37 ± 3 vs. 47 ± 2% in Sham) associated with increased myocardial cytokines (Interleukin-17, Interleukin-6, and Interleukin-4). This study shows that experimental Periodontitis caused cardiac dysfunction, increased heart cytokines, and sympathetic overactivity, in line with epidemiological studies indicating an increased risk of cardiovascular events in clinical Periodontitis.

Periodontal status, vascular reactivity, and platelet aggregation changes in rats submitted to hypercholesterolemic diet and periodontitis.

BACKGROUND AND OBJECTIVES: Periodontitis can corroborate with development and progression of atherosclerosis and a possible bidirectional interaction between both pathologies has been hypothesized. The aim of this work was to study the interactions between diet-induced hypercholesterolemia and ligature-induced periodontitis in Wistar rats submitted to both conditions. MATERIAL AND METHODS: Animals were divided into four experimental groups: C (control: standard diet without periodontitis), Perio (periodontitis plus standard diet), HC (high cholesterol diet without periodontitis), and HC + Perio (high cholesterol diet plus periodontitis). The diets were offered for 45 days and a silk ligature was applied in the lower first molars of Perio and HC-Perio animals on day 34 and maintained for 11 days until euthanasia. The mandibles were excised, and alveolar bone loss was determined by macroscopic and micro-tomographic (µ-CT) imaging. Blood samples were obtained, and platelet aggregation was induced in plasma rich in platelets by adenosine diphosphate (ADP) and collagen. Endothelium-dependent vascular reactivity and protein expression of endothelial (eNOS), phosphorylated endothelial (peNOS), and inducible (iNOS) nitric oxide synthases were evaluated in aorta samples. RESULTS: The HC diet combined with periodontitis (HC + Perio group) was associated with an increased alveolar bone loss, when compared to the other groups. Both in Perio and HC groups, platelet aggregation induced by ADP or collagen was increased, while maximum aortic relaxation induced by acetylcholine was decreased. Periodontitis or HC diet alone decreased the expression of peNOS and HC diet increased the expression of iNOS. In contrast, no additive or synergistic effects were found in vascular reactivity or in platelet aggregation when the two conditions were associated (HC + Perio group). CONCLUSION: Hypercholesterolemia accelerated the process of bone loss induced by periodontitis while a high cholesterol diet or periodontitis individually increased platelet aggregation and vascular reactivity in rats without additive or synergistic effects, when associated.

Tyrosine-protein phosphatase non-receptor type 2 inhibits alveolar bone resorption in diabetic periodontitis via dephosphorylating CSF1 receptor.

Tyrosine-protein phosphatase non-receptor type 2 (PTPN2) is an important protection factor for diabetes and periodontitis, but the underlying mechanism remains elusive. This study aimed to identify the substrate of PTPN2 in mediating beneficial effects of 25-Hydroxyvitamin D3 (25(OH)2D3 ) on diabetic periodontitis. 25(OH)2D3 photo-affinity probe was synthesized with the minimalist linker and its efficacy to inhibit alveolar bone loss, and inflammation was evaluated in diabetic periodontitis mice. The probe was used to pull down the lysates of primary gingival fibroblasts. We identified PTPN2 as a direct target of 25(OH)2D3 , which effectively inhibited inflammation and bone resorption in diabetic periodontitis mice. In addition, we found that colony-stimulating factor 1 receptor (CSF1R) rather than JAK/STAT was the substrate of PTPN2 to regulate bone resorption. PTPN2 direct interacted with CSF1R and dephosphorylated Tyr807 residue. In conclusion, PTPN2 dephosphorylates CSF1R at Y807 site and inhibits alveolar bone resorption in diabetic periodontitis mice. PTPN2 and CSF1R are potential targets for the therapy of diabetic periodontitis or other bone loss-related diseases.

Evaluation of Implant Success in Patients with Dental Aplasia.

INTRODUCTION: Dental aplasia is an anomaly in which the number of teeth is reduced. It is the most commonly occurring dental anomaly during tooth development. Treatment management of patients with dental aplasia is challenging. OBJECTIVES: The aim of this retrospective clinical study was to analyze the survival and success rates of dental implants placed in hypodontic patients, rated with different criteria. METHODS: Forty-three patients were diagnosed with dental aplasia and treated with dental implants between November 2000 and February 2016. The variables assessed included the plaque level, bleeding on probing, probing depth, implant mobility, implant stability, and implant loss. To analyze the peri-implant bone level, a panoramic X-ray of each patient was taken. The results were compared with X-rays taken immediately after implantation. RESULTS: Thirty-seven patients (16 males; 21 females) participated in this study. In total, 155 implants (86 maxillary; 69 mandibular) were inserted. Two of the 155 implants failed; the in situ survival rate was 98.7%. The success rate according to the criteria of Buser et al. was 96.8%, and that according to the criteria of Albrektsson et al. was 88.4%. CONCLUSION: The survival and success rates of dental implants in patients with congenitally absent teeth were very high and did not differ significantly from results achieved in an unaffected population. Dental implants are a reliable therapy for patients with dental aplasia.

Alveolar Bone Density Reduction in Rats Caused by Unilateral Nasal Obstruction

Background: Oral breathing can cause morphological changes in the oral and maxillofacial regions. Aims: To investigate whether oral breathing affected structural changes in bone tissues. Study Design: Animal experimentation. Methods: A total of 48 8-day-old male Sprague−Dawley rats were divided into two groups: a breathing group and a sham (control) group. All Sprague−Dawley rats were killed at 7 weeks after unilateral nostril obstruction modeling. Then, structural changes in bone tissues were detected by micro-computed tomography, and the expression levels of receptor activator of nuclear factor-κB, osteoprotegerin, and receptor activator of nuclear factor-κB ligand in the signal pathway of bone metabolism within the local alveolar bone and serum of rats were detected by reverse transcription-quantitative polymerase chain reaction and Western blotting. Results: The results showed that receptor activator of nuclear factor-κB ligand and receptor activator of nuclear factor-κB levels in bone tissues and serum in the oral breathing group were higher than those in the control group [Maxillary alveolar bone: receptor activator of nuclear factor-κB ligand (pRNA=0.009, pprotein=0.008), receptor activator of nuclear factor-κB (pRNA=0.008, pprotein=0.009); Mandibular alveolar bone: receptor activator of nuclear factor-κB ligand (pRNA=0.047, pprotein=0.042), receptor activator of nuclear factor-κB (pRNA=0.041, pprotein=0.007); Serum: receptor activator of nuclear factor-κB ligand (pRNA<0.001, pprotein<0.001), receptor activator of nuclear factor-κB (pRNA<0.001, pprotein<0.001)], along with decreased osteoprotegerin expression (Maxillary alveolar bone: pRNA=0.038, pprotein=0.048; Mandibular alveolar bone: pRNA<0.001, pprotein<0.001; Serum: pRNA=0.009, pprotein=0.006) and elevated receptor activator of nuclear factor-κB ligand/osteoprotegerin. Micro-computed tomography analysis indicated a significant difference in the level of bone volume fraction, as well as trabecular thickness in maxillary alveolar bone between the experimental and control groups (p=0.049, p=0.047). Meanwhile, trabecular thickness, and cortical thickness levels in mandibular alveolar bone also differed significantly between the experimental and control groups (p=0.043, p=0.024). Conclusion: Structural changes of the respiratory system affect the alveolar bone structure and unilateral nasal obstruction may lead to a change in regional specific bone density.

WNT3A accelerates delayed alveolar bone repair in ovariectomized mice.

Our goal was to evaluate alveolar bone healing in OVX mice, and to assess the functional utility of a WNT-based treatment to accelerate healing in mice with an osteoporotic-like bony phenotype. INTRODUCTION: Is osteoporosis a risk factor for dental procedures? This relatively simple question is exceedingly difficult to answer in a clinical setting, for two reasons. First, as an age-related disease, osteoporosis is frequently accompanied by age-related co-morbidities that can contribute to slower tissue repair. Second, the intervals at which alveolar bone repair are assessed in a clinical study are often measured in months to years. This study aimed to evaluate alveolar bone repair in ovariectomized (OVX) mice and provide preclinical evidence to support a WNT-based treatment to accelerate alveolar bone formation. METHODS: OVX was performed in young mice to produce an osteoporotic-like bone phenotype. Thereafter, the rate of extraction socket healing and osteotomy repair was assessed. A liposomal WNT3A treatment was tested for its ability to promote alveolar bone formation in this OVX-induced model of bone loss. RESULTS: Bone loss was observed throughout the murine skeleton, including the maxilla, and mirrored the pattern of bone loss observed in aged mice. Injuries to the alveolar bone, including tooth extraction and osteotomy site preparation, both healed significantly slower than the same injuries produced in young controls. Given sufficient time, however, all injuries eventually healed. In OVX mice, osteotomies healed significantly faster if they were treated with L-WNT3A. CONCLUSIONS: Alveolar bone injuries heal slower in OVX mice that exhibit an osteoporotic-like phenotype. The rate of alveolar bone repair in OVX mice can be significantly promoted with local delivery of L-WNT3A.

Effect of Misfit at Implant-Level Framework and Supporting Bone on Internal Connection Implants: Mechanical and Finite Element Analysis.

PURPOSE: To evaluate the effect of misfit at implant-level fixed partial dentures (ILFPDs) and marginal bone support on the generation of implant cracks. MATERIALS AND METHODS: This in vitro study included a mechanical fatigue test and finite element analysis. A mechanical cycling loading test was performed using 16 experimental models, each consisting of two parallel implants subdivided into four groups based on the misfit and the supporting bone condition. The framework, firmly seated at implants, was dynamically loaded vertically with a force of 1,600/160 N and 15 Hz for 1 × 106 cycles. Optical microscope, scanning electron microscope (SEM), and computed tomography three-dimensional (CT-3D) analyses were performed to detect impairments. Finite element models, representing the setups in the mechanical fatigue test, were used to represent the fatigue life. RESULTS: None of the mechanical components presented distortion or fracture at the macroscopic level during the test. In a microscopy evaluation, the fatigue test revealed scratches visible in the inner part of the conical portion of the implants regardless of the groups. SEM and CT-3D analysis revealed one implant from the misfit/no bone loss group with a microfracture in the inner part of the conical interface. The simulated effective stress levels in the coronal body were higher in the misfit groups compared with the no misfit groups. The misfit groups presented effective stress levels, above 375 MPa, that penetrated the entire wall thickness. The no bone loss group presented an effective stress level above 375 MPa along its axial direction. In the no misfit group, the area presenting effective stress levels above 375 MPa in the conical connection was larger for the bone loss group compared with the no bone loss group. CONCLUSION: This study confirmed that implant fracture is an unlikely adverse event. A clear pattern of effective distribution greater than fatigue limit stresses could be noticed when the misfit was present. The dynamic load simulation demonstrated that the crack is more likely to occur when implants are fully supported by marginal bone compared with a bone loss scenario. Within the limitations of this study, it is speculated that marginal bone loss might follow the appearance of an undetected crack. Further research is needed to develop safe clinical protocols with regard to ILFPD.

Activation of vitamin D in the gingival epithelium and its role in gingival inflammation and alveolar bone loss.

BACKGROUND AND OBJECTIVE: Both chronic and aggressive periodontal disease are associated with vitamin D deficiency. The active form of vitamin D, 1,25(OH)2 D3 , induces the expression of the antimicrobial peptide LL-37 and innate immune mediators in cultured human gingival epithelial cells (GECs). The aim of this study was to further delineate the mechanism by which vitamin D enhances the innate defense against the development of periodontal disease (PD). MATERIALS AND METHODS: Wild-type C57Bl/6 mice were made deficient in vitamin D by dietary restriction. Cultured primary and immortalized GEC were stimulated with 1,25(OH)2 D3 , followed by infection with Porphyromonas gingivalis, and viable intracellular bacteria were quantified. Conversion of vitamin D3 to 25(OH)D3 and 1,25(OH)2 D3 was quantified by ELISA. Effect of vitamin D on basal IL-1α expression in mice was determined by topical administration to the gingiva of wild-type mice, followed by qRT-PCR. RESULTS: Dietary restriction of vitamin D led to alveolar bone loss and increased inflammation in the gingiva in the mouse model. In primary human GEC and established human cell lines, treatment of GEC with 1,25(OH)2 D3 inhibited the intracellular growth of P. gingivalis. Cultured GEC expressed two 25-hydroxylases (CYP27A1 and CYP2R1), as well as 1-α hydroxylase, enabling conversion of vitamin D to both 25(OH)D3 and 1,25(OH)2 D3 . Topical application of both vitamin D3 and 1,25(OH)2 D3 to the gingiva of mice led to rapid inhibition of IL-1α expression, a prominent pro-inflammatory cytokine associated with inflammation, which also exhibited more than a 2-fold decrease from basal levels in OKF6/TERT1 cells upon 1,25(OH)2 D3 treatment, as determined by RNA-seq. CONCLUSION: Vitamin D deficiency in mice contributes to PD, recapitulating the association seen in humans, and provides a unique model to study the development of PD. Vitamin D increases the activity of GEC against the invasion of periodontal pathogens and inhibits the inflammatory response, both in vitro and in vivo. GEC can convert inactive vitamin D to the active form in situ, supporting the hypothesis that vitamin D can be applied directly to the gingiva to prevent or treat periodontal disease.

Notch signaling pathway mediates alveolar bone resorption in apical periodontitis.

Apical periodontitis represents a chronic inflammatory process within periapical tissues, mostly caused by etiological agents of endodontic origin. Progressive bone resorption in the periapical region represents the hallmark of apical periodontitis and occurs as the consequence of interplay between polymicrobial infections and host response. The Notch signaling pathway is an evolutionary conserved cell-signaling system that plays an important role in a variety of cell functions including proliferation, differentiation and apoptosis. In recent years its involvement in bone homeostasis has attracted a significant consideration. We hypothesized that Notch signaling pathway, which has a complex interplay with proinflammatory cytokines and bone resorption regulators, contributes to alveolar bone resorption via increased Notch receptors on immune cell surface and stimulates Notch receptor intracellular domain (NICD) translocation into the nucleus. The potential benefit of medications aimed to down-regulate these pathways in apical periodontitis treatment remains to be assessed.

Berberine Ameliorates Periodontal Bone Loss by Regulating Gut Microbiota.

Postmenopausal osteoporosis (PMO) is a risk factor for periodontitis, and current therapeutics against PMO prevent the aggravated alveolar bone loss of periodontitis in estrogen-deficient women. Gut microbiota is recognized as a promising therapeutic target for PMO. Berberine extracted from Chinese medicinal plants has shown its effectiveness in the treatment of metabolic diseases such as obesity and diabetes via regulating gut microbiota. Here, we hypothesize that berberine ameliorates periodontal bone loss by improving the intestinal barriers by regulating gut microbiota under an estrogen-deficient condition. Experimental periodontitis was established in ovariectomized (OVX) rats, and the OVX-periodontitis rats were treated with berberine for 7 wk before sacrifice for analyses. Micro-computed tomography and histologic analyses showed that berberine treatment significantly reduced alveolar bone loss and improved bone metabolism of OVX-periodontitis rats as compared with the vehicle-treated OVX-periodontitis rats. In parallel, berberine-treated OVX-periodontitis rats harbored a higher abundance of butyrate-producing gut microbiota with elevated butyrate generation, as demonstrated by 16S rRNA sequencing and high-performance liquid chromatography analysis. Berberine-treated OVX-periodontitis rats consistently showed improved intestinal barrier integrity and decreased intestinal paracellular permeability with a lower level of serum endotoxin. In parallel, IL-17A-related immune responses were attenuated in berberine-treated OVX-periodontitis rats with a lower serum level of proinflammatory cytokines and reduced IL-17A+ cells in alveolar bone as compared with vehicle-treated OVX-periodontitis rats. Our data indicate that gut microbiota is a potential target for the treatment of estrogen deficiency-aggravated periodontal bone loss, and berberine represents a promising adjuvant therapeutic by modulating gut microbiota.

Efficacy of Alveolar Ridge Preservation after Maxillary Molar Extraction in Reducing Crestal Bone Resorption and Sinus Pneumatization: A Multicenter Prospective Case-Control Study.

AIM: To evaluate, with three-dimensional analysis, the effectiveness of alveolar ridge preservation (ARP) after maxillary molar extraction in reducing alveolar bone resorption and maxillary sinus pneumatization when compared to unassisted socket healing. METHODS: Patients were included in the study following inclusion criteria and underwent minimally traumatic maxillary molar extraction followed by ARP using synthetic nanohydroxyapatite (Fisiograft Bone, Ghimas, Italy) (test group) or unassisted socket healing (control group). Cone-beam computerized tomographies (CBCT) were performed immediately after tooth extraction (T0) and 6 months postoperatively (T1). CBCTs were superimposed by using a specific software (Amira, Thermo Fisher Scientific, USA) and the following items were analyzed in both groups: (i) postextractive maxillary sinus floor expansion in coronal direction and (ii) postextractive alveolar bone dimensional changes (both vertical and horizontal). All data were tested for normality and equality of variance and subsequently analyzed by independent samples T-test and Mann-Whitney test. RESULTS: Thirty patients were treated by three centers and twenty-six (test n=13; control n=13) were included in the final analysis. Mean sinus pneumatization at T1 was 0.69±0.48 mm in the test group and 1.04±0.67 mm in the control group (p=0.15). Mean vertical reduction of the alveolar bone at T1 was 1.62±0.49 mm in the test group and 2.01±0.84 mm in the control group (p=0.08). Mean horizontal resorption of crestal bone at T1 was 2.73±1.68 mm in test group and 3.63±2.24 mm in control group (p=0.24). CONCLUSIONS: It could be suggested that ARP performed after maxillary molar extraction may reduce the entity of sinus pneumatization and alveolar bone resorption, compared to unassisted socket healing. This technique could decrease the necessity of advanced regenerative procedures prior to dental implant placement in posterior maxilla.

The role of potassium channels in the endothelial dysfunction induced by periodontitis.

OBJECTIVE: Periodontitis is associated with endothelial dysfunction, which is clinically characterized by a reduction in endothelium-dependent relaxation. However, we have previously shown that impairment in endothelium-dependent relaxation is transient. Therefore, we evaluated which mediators are involved in endothelium-dependent relaxation recovery. MATERIAL AND METHODS: Rats were subjected to ligature-induced experimental periodontitis. Twenty-one days after the procedure, the animals were prepared for blood pressure recording, and the responses to acetylcholine or sodium nitroprusside were obtained before and 30 minutes after injection of a nitric oxide synthase inhibitor (L-NAME), cyclooxygenase inhibitor (Indomethacin, SC-550 and NS- 398), or calcium-dependent potassium channel blockers (apamin plus TRAM- 34). The maxilla and mandible were removed for bone loss analysis. Blood and gingivae were obtained for C-reactive protein (CRP) and myeloperoxidase (MPO) measurement, respectively. RESULTS: Experimental periodontitis induces bone loss and an increase in the gingival MPO and plasmatic CRP. Periodontitis also reduced endothelium-dependent vasodilation, a hallmark of endothelial dysfunction, 14 days after the procedure. However, the response was restored at day 21. We found that endothelium-dependent vasodilation at day 21 in ligature animals was mediated, at least in part, by the activation of endothelial calcium-activated potassium channels. CONCLUSIONS: Periodontitis induces impairment in endothelial-dependent relaxation; this impairment recovers, even in the presence of periodontitis. The recovery is mediated by the activation of endothelial calcium-activated potassium channels in ligature animals. Although important for maintenance of vascular homeostasis, this effect could mask the lack of NO, which has other beneficial properties.

Orthognathic surgery Deteriorates the osseointegration of dental implants: A propensity-matched multicentre cohort study.

This study aimed to investigate the possible influence of the regional acceleratory phenomenon (RAP) on dental implant osseointegration. Orthognathic surgery was set as an intervention for RAP, and a multicentre cohort study of two groups was undertaken. Group O included patients with single implant placement at least 4 months after orthognathic surgery and functional loading for more than 1 year, while controls (Group C) were without any major surgery. Clinical and radiographic assessments of implants, including changes in marginal bone levels, were analysed at baseline, 6- and 12-month follow-up. Bivariate analysis of two groups with propensity score matching was performed. After propensity score matching, all 10 confounding variables had acceptable standardised difference scores (<20%), indicating that the matching procedure had efficiently balanced the two groups. Following the propensity score adjustment, the marginal bone loss was significantly higher in Group O than the control at 6 months (1.66 ± 1.05 mm vs 0.59 ± 0.64 mm, P < 0.001) and 12 months (2.30 ± 1.27 mm vs 0.82 ± 0.78 mm, P < 0.001). Compared to Group C, subjects in Group O had a higher incidence of peri-implant mucositis and implantitis (11.8% vs 1.5%, P = 0.033). Impaired osseointegration of dental implants was associated with orthognathic surgery. Special considerations for peri-implant soft and hard tissue stability should be addressed to obtain ideal treatment results and prognosis for patients who have had prior orthognathic surgery.

Stability and bone loss around submerged and non-submerged implants in diabetic and non-diabetic patients: a 7-year follow-up.

To evaluate peri-implant bone loss (PIBL) and stability around submerged and non-submerged dental implants in patients with and without type 2 diabetes mellitus (T2DM). Thirty-five T2DM and non-diabetic (NT2DM) patients were included in this study. Demographic data were recorded using a questionnaire and PIBL was measured on digital radiographs. Resonance frequency analysis (RFA) was carried out for each implant at the time of fixture placement and at 3 months in both groups. P values less than 0.05 were considered statistically significant. One hundred and eighteen dental implants with a mean height of 10 to 12 mm and 3.3 to 4.1 mm in diameter were placed. The comparison of the mean RFA values at baseline and at 3 months was statistically significant (p = 0.008) in T2DM patients. The inter-group mean RFA values at baseline and at 3 months were not significant (p > 0.05). PIBL was significantly high in T2DM as compared to NT2DM patients at each follow-up (p < 0.05). At 2, 3, and 7 years, non-submerged dental implants showed significantly high PIBL in T2DM patients as compared to NT2DM individuals (p<0.05). The results of the present clinical study demonstrate increased PIBL around non-submerged single-tooth implant-supported restorations in T2DM patients, which may be due to the immune inflammatory status.

The effects of dentoalveolar distraction extraction on alveolar ridge preservation: Cone-beam computed tomography and X-ray analysis in canine model.

OBJECTIVE: This study aims to evaluate the effect of dentoalveolar distraction extraction (DDE) on site preservation, and to evaluate how the technique keeps the height and width of alveolar bones to a greater extent. METHODS: 12 beagle dogs, randomly divided into three groups (DDE group, NH group, BOG group), were used. In the dogs of three groups, the root of the left or right third mandibular premolars were respectively extracted by three methods namely, DDE, traditional extraction with natural healing, and traditional extraction with Bio-Oss bone dust implanted and guided bone regeneration (GBR). Cone-beam computed tomography (CBCT) scans and X-rays were taken immediately and three months after the tooth extraction. The height and width of the alveolar ridges were compared among different groups. RESULTS: Three months after tooth extraction, at the 1 mm level below the alveolar ridge crest, the amount and degree of buccal alveolar ridge width resorption in DDE group were significantly lower than that of NH and BOG group (P < 0.05). At the 2 mm and 3 mm level below the alveolar ridge crest, the amount and degree of buccal alveolar ridge width resorption in DDE group and BOG had no significant difference, and both were significant lower than that of NH group (P < 0.05). The height resorption of alveolar ridge in DDE group was significantly lower than NH and BOG groups (P < 0.05), while NH and BOG group had no statistically significant. CONCLUSIONS: To a greater extent, the alveolar ridge preservation through DDE could preserve the height and width of alveolar ridge crest.

Splinted and unsplinted overdenture attachment systems: A systematic review and meta-analysis.

Splinted and unsplinted overdenture attachment systems have unique advantages and disadvantages. The aim of the present systematic review was to determine the influence of splinted and unsplinted overdenture attachment systems on the marginal bone loss, prosthetic complications and implant survival rate. PubMed/MEDLINE, Scopus and Cochrane databases were searched for articles published up to October 2017, using the following search terms: "overdenture AND attachment OR overdenture AND bar OR overdenture splinted." The PICO question "Do splinted overdenture attachment systems promote better clinical results in comparison to unsplinted systems?" was evaluated. Eligible studies included randomized controlled clinical trials, prospective studies with at least 10 participants and a minimum follow-up of 6 months, and studies published in English that compared splinted and unsplinted attachment systems within the same study. The 95% confidence interval (CI) was considered for all outcomes analysed. After completion of the different steps in the article selection process, nine articles were included in the qualitative and quantitative analyses. A total of 984 implants were placed in 380 patients (mean age: 62.8 years). The meta-analysis demonstrated no statistically significant differences between splinted and unsplinted attachment systems with regard to marginal bone loss (P = .39; MD: -0.11; 95% CI: -0.37 to 0.14), complications (P = .31; RR: 1.26; CI: 0.80-1.99) and implant survival rate (P = .14; RR: 0.37% CI: 0.10-1.36). In addition, splinted and unsplinted overdenture attachment systems achieved similar results with regard to marginal bone loss, prosthetic complications and implant survival rate.

Mechanical adaptation of trabecular bone morphology in the mammalian mandible.

Alveolar bone, together with the underlying trabecular bone, fulfils an important role in providing structural support against masticatory forces. Diseases such as osteoporosis or periodontitis cause alveolar bone resorption which weakens this structural support and is a major cause of tooth loss. However, the functional relationship between alveolar bone remodelling within the molar region and masticatory forces is not well understood. This study investigated this relationship by comparing mammalian species with different diets and functional loading (Felis catus, Cercocebus atys, Homo sapiens, Sus scrofa, Oryctolagus cuniculus, Ovis aries). We performed histomorphometric analyses of trabecular bone morphology (bone volume fraction, trabecular thickness and trabecular spacing) and quantified the variation of bone and tooth root volumes along the tooth row. A principal component analysis and non-parametric MANOVA showed statistically significant differences in trabecular bone morphology between species with contrasting functional loading, but these differences were not seen in sub-adult specimens. Our results support a strong, but complex link between masticatory function and trabecular bone morphology. Further understanding of a potential functional relationship could aid the diagnosis and treatment of mandibular diseases causing alveolar bone resorption, and guide the design and evaluation of dental implants.

Decoronation followed by dental implants placement: fundamentals, applications and explanations.

Dental arches areas with teeth presenting dentoalveolar ankylosis and replacement root resorption can be considered as presenting normal bone, in full physiological remodeling process; and osseointegrated implants can be successfully placed. Bone remodeling will promote osseointegration, regardless of presenting ankylosis and/or replacement root resorption. After 1 to 10 years, all dental tissues will have been replaced by bone. The site, angulation and ideal positioning in the space to place the implant should be dictated exclusively by the clinical convenience, associated with previous planning. One of the advantages of decoronation followed by dental implants placement in ankylosed teeth with replacement resorption is the maintenance of bone volume in the region, both vertical and horizontal. If possible, the buccal part of the root, even if thin, should be preserved in the preparation of the cavity for the implant, as this will maintain gingival tissues looking fully normal for long periods. In the selection of cases for decoronation, the absence of microbial contamination in the region - represented by chronic periapical lesions, presence of fistula, old unconsolidated root fractures and active advanced periodontal disease - is important. Such situations are contraindications to decoronation. However, the occurrence of dentoalveolar ankylosis and replacement resorption without contamination should neither change the planning for implant installation, nor the criteria for choosing the type and brand of dental implant to be used. Failure to decoronate and use dental implants has never been reported.

Comparing osteogenic effects between concentrated growth factors and the acellular dermal matrix.

Concentrated growth factor (CGF) is an autogenuous product that contains highly concentrated number of platelets and can be derived from venous blood by selective centrifugation. It has been speculated that local growth factors in human platelets (insulinlike growth factor, IGF; transforming growth factor, TGF-b; platelet derived growth factor, PDGF) would enhance healing of grafts and also counteract resorption. The osteogensis effect of CGF and acellular dermal matrix (ADM) for alveolar cleft defects was evaluated in this study. Twenty alveolar cleft patients were divided randomly into two groups. One group underwent guided bone regeneration (GBR) using acellular dermal matrix film combined with alveolar bone grafting using iliac crest bone grafts (GBR group), while the other group underwent alveolar bone grafting combined with CGF (CGF group). Cone beam computed tomography (CBCT) images were obtained at 1 week and 6 months following the procedure. Using Mimics 17.0 software, the bone resorption rate and bone density improvement rate were calculated and compared between the two groups. Although not significant between ADM and CGF in bone resorption rate, the bone density improvement in cases with CGF(61.62 ± 4.728%) was much better than in cases with ADM (27.05 ± 5.607%) (p = 0.0002). Thus, CGF could be recommended to patients with alveolar cleft as a better choice.