Porcelain Fracture Resistance of Screw‐Retained,Cement‐Retained,and Screw‐Cement‐Retained Implant‐Supported Metal Ceramic Posterior Crowns

Purpose: The purpose of this in vitro study was to compare the porcelain fracture resistance between screw‐retained, cement‐retained, and combined screw‐ and cement‐retained metal–ceramic (MC) implant‐supported posterior single crowns; and to investigate the effect of offsetting the occlusal screw‐access opening on porcelain fracture resistance of screw‐retained and cement‐retained MC implant‐supported posterior single crowns. Materials and Methods: Forty standardized MC molar‐shaped restorations were fabricated. The 40 restorations were divided into four groups (SRC, SRO, CRP, and CSC) of 10 specimens each. Group SRC: screw‐retained, screw‐access hole placed in the center of the occlusal surface; Group SRO: screw‐retained, screw access hole placed 1 mm offset from the center of the occlusal surface toward the buccal cusp; Group CRP: cement‐retained, zinc phosphate cement was used; Group CSC: cement‐retained with a screw‐access hole in the center of the occlusal surface. The screw‐retained restorations and abutments were directly attached to 3i implant fixtures embedded in acrylic resin blocks. Subsequently, all test specimens were thermocycled and vertically loaded in a universal testing machine at a crosshead speed of 2 mm/min until fracture. Mean values of load at fracture (in N) were calculated in each group and compared with a one‐way ANOVA and Tukey's Studentized test (α= 0.05). Results: Mean values of loads required to fracture the restorations were as follows (N): Group SRC: 1721 ± 593; Group SRO: 1885 ± 491; Group CRP: 3707 ± 1086; Group CSC: 1700 ± 526. Groups SRC, SRO, and CSC required a significantly lower force to fracture the porcelain than did the CRP group (p < 0.05). Conclusion: The cement‐retained restorations showed significantly higher mean fracture loads than the restorations having screw‐access openings in their occlusal surface. The position of the screw‐access hole within the occlusal surface did not significantly affect the porcelain fracture resistance.     

Orthodontic treatment need,self‐esteem,and oral health‐related quality of life among 12‐yr‐old schoolchildren

The aim of this study was to investigate the association between orthodontic treatment need and oral health‐related quality of life (OHRQoL) among 12‐yr‐old children. The study also assessed whether self‐esteem modifies and/or moderates this relationship. Cross‐sectional data on 406 schoolchildren aged 12 yr were analyzed. Data on socio‐economic and demographic characteristics, dental pain, self‐esteem, and OHRQoL were collected using validated questionnaires. Orthodontic treatment need was assessed, through dental examinations, using the dental aesthetic index (DAI). Multiple negative binomial regression and path analysis were used to estimate the association of orthodontic treatment need and self‐esteem with OHRQoL. A modifying effect of self‐esteem on the relationship between DAI and OHRQoL was observed. Self‐esteem did not mediate the abovementioned relationship. Children with lower scores of self‐esteem had worse OHRQoL among those with lower orthodontic treatment need (a DAI score of < 31). However, self‐esteem did not influence the association between DAI and OHRQoL in children with greater orthodontic treatment need (a DAI score of ≥ 31). Self‐esteem attenuated the impact of malocclusion on OHRQoL in children with minor or definite malocclusion, but not among those with severe or very severe malocclusion. Self‐esteem appears to buffer the impact of malocclusion on OHRQoL in children with minor orthodontic treatment need.     

Crevicular fluid matrix metalloproteinase‐8, ‐13, and TIMP‐1 levels in type 2 diabetics

Oral Diseases (2010) 16 , 476–481 Objectives: To evaluate whether type 2 diabetes mellitus (DM) enlarged and if so the quantum of such increase in the gingival crevicular fluid (GCF) levels of matrix metalloproteinase‐8 (MMP‐8), MMP‐13 and tissue inhibitor of metalloproteinases‐1 (TIMP‐1). Methods: Subjects (n = 73) were divided into five groups as follows: 12 DM patients with gingivitis (DM‐G), 12 DM patients with periodontitis (DM‐P), 12 systemically healthy patients with gingivitis (H‐G), 13 systemically healthy patients with periodontitis (H‐P) and 24 periodontally, systemically healthy volunteer subjects (H‐C). Full‐mouth clinical periodontal measurements were performed at six sites per tooth. Gingival crevicular fluid samples were obtained from two sites representing the clinical periodontal diagnosis in single‐rooted teeth. Gingival crevicular fluid levels of MMP‐8, MMP‐13 and TIMP‐1 were analysed by immunofluorometric MMP assay (IFMA), enzyme‐linked immunosorbent assay (ELISA). Data were tested statistically by parametric tests. Results: All clinical periodontal measurements were similar in both diabetic and systemically healthy patients with periodontal disease (all P > 0.05). Total amounts of MMP‐8 in GCF samples were significantly lower in H‐C group than DM‐G, DM‐P, H‐P groups (all P < 0.05). Matrix metalloproteinase‐13, TIMP‐1 total amounts were similar in study groups (P > 0.05). Diabetes mellitus patients exhibited similar levels of MMP‐8, MMP‐13, TIMP‐1 with systemically healthy gingivitis/periodontitis patients (P > 0.05). Conclusions: Within the limits of this study, DM does not seem to significantly affect GCF levels of MMP‐8, MMP‐13, TIMP‐1 or clinical periodontal status.     

Stimulation of epithelial cell matrix metalloproteinase (MMP‐2, ‐9, ‐13) and interleukin‐8 secretion by fusobacteria

Background/aims: Bacterial pathogens involved in periodontal diseases exert their destructive effects primarily by stimulating the host cells to increase their secretion of proinflammatory cytokines and matrix metalloproteinases (MMPs). This study aimed to determine the epithelial cell matrix metalloproteinase and interleukin‐8 (IL‐8) secretion upon exposure to fusobacteria. Methods: Eight different oral and non‐oral Fusobacterium strains were incubated with HaCaT epithelial cells. Gelatin zymography and Western blot analysis were performed to detect collagenase 3 (MMP‐13), gelatinase A (MMP‐2), gelatinase B (MMP‐9), and IL‐8 secretion by epithelial cells. Results: All Fusobacterium strains, especially Fusobacterium necrophorum ATCC 25286, Fusobacterium nucleatum ATCC 25586, and Fusobacterium varium ATCC 51644, increased MMP‐9 and MMP‐13 secretion. Fusobacterium simiae ATCC 33568, and to a lesser extent F. nucleatum and F. necrophorum, increased epithelial MMP‐2 secretion. F. nucleatum and F. necrophorum also increased IL‐8 secretion. F. varium ATCC 27725, a strain that only weakly stimulated MMP production, strongly increased the IL‐8 production, suggesting that their expression is differently regulated. Conclusion: We conclude that the pathogenic potential of fusobacteria may partly result from their ability to stimulate secretion of MMP‐9, MMP‐13, and IL‐8 from epithelial cells.     

Tumor Necrosis Factor‐α Induces Matrix Metalloproteinases‐3, ‐10, and ‐13 in Human Periodontal Ligament Cells

Background: Various biologic mediators, including matrix metalloproteinases (MMPs), that are implicated in periodontal tissue breakdown can be induced by cytokines. MMPs are known to degrade periodontal ligament attachment, and bone matrix proteins and tissue inhibitors of metalloproteinase (TIMPs) inhibit the activity of MMPs. The aim of this study is to investigate the effect of tumor necrosis factor (TNF)‐α on the expression of MMPs in human periodontal ligament (PDL) cells in vitro and establish which MMPs are expressed specifically in response to that stimulus. Methods: Cultured PDL cells were stimulated with TNF‐α and analyzed with an MMP antibody array. Real‐time polymerase chain reaction (PCR), enzyme‐linked immunosorbent assay (ELISA), and western blot with cell lysate and zymography were used to measure messenger RNA (mRNA) and protein levels of MMP‐3, ‐10, and ‐13. To examine TNF receptor (TNFR) expression, PDL cells were examined by flow cytometry, and expression of MMP‐3, ‐10, and ‐13 was observed after blocking the TNFR with an antagonist. Results from real‐time PCR, ELISA, and western blot were analyzed by paired t test. Results: The antibody array showed that the protein most strongly upregulated by TNF‐α stimulation was MMP‐3, followed by MMP‐13 and MMP‐10. The TNF‐α receptor blocker specifically inhibited expression of MMP‐3 and ‐13. In addition, TNF‐α increased levels of MMP mRNAs in MMP‐3, ‐13, and ‐10 (in decreasing order). However, ELISAs showed that MMP‐13 was the most upregulated protein, followed by MMP‐10 and MMP‐3. Western blotting indicated that TNF‐α increased MMP‐3 and ‐13 levels but had no significant effect on the level of MMP‐10, and zymography showed that TNF‐α increased the activities of all forms of MMP‐3 and ‐13, but MMP‐10 was not detected. Flow cytometry demonstrated that the majority of PDL cells expressed TNFR1. Conclusions: TNF‐α (10 ng/mL) upregulates levels of MMP‐3, ‐10, and ‐13 in human PDL cells. These results suggest that these proteins play an important role in the inflammation of PDLs.     

Cost‐effectiveness,in a randomized trial,of glass‐ionomer‐based and resin sealant materials after 4 yr

This study, conducted from a government program perspective, compared the incremental cost‐effectiveness of oral health interventions, in particular their delivery to underserved populations in whom dental sealants constitute an important, high‐yielding complement to toothbrushing in dental‐caries prevention. The study data concern the relative cost‐effectiveness of three sealant materials in four approaches to prevent cavitated dentine carious lesions in permanent molars in a community intervention trial among school‐age children in Wuhan, China. The four approaches were high‐viscosity glass‐ionomer cement without heat application (HVGIC); high‐viscosity glass‐ionomer cement with heat application [light‐emitting diode (LED) thermocured HVGIC]; glass‐carbomer; and composite resin. The costs studied were: cost of sealing permanent molars; adverse event costs for restoring cavitated dentine carious lesions developing within 4 yr in study data; and projections of 1,000 sealants per group. Preventing one more cavitated dentine carious lesion cost US$105 for the study data when comparing HVGIC (n = 405) with composite resin (n = 396) and US$59 per 1,000 sealants in the projections; LED thermocured HVGIC compared with composite resin cost US$115 for one more cavitated lesion and US$52 per 1,000 sealants, respectively. Although more expensive than composite resin, LED thermocured HVGIC was identified as the most cost‐effective among the sealant materials studied. Ease of application, minimal technical and infrastructure requirements, and cost‐effectiveness make glass‐ionomers a practicable option for governments making decisions under economic constraints.