Attenuation of radiation‐ and chemoradiation‐induced mucositis using gamma‐d‐glutamyl‐l‐tryptophan (SCV‐07)

Oral Diseases (2010) 16 , 655–660 Objective: To evaluate the efficacy of a novel immunomodulating peptide (SCV‐07) in attenuating the course of radiation‐induced mucositis in an established animal model of oral mucositis (OM). Material and Methods: In three separate experiments, golden Syrian hamsters received either an acute radiation challenge to the buccal mucosa of eight fractionated doses of 7.5 Gy of radiation over a 2‐week‐period, or a combination of acute radiation and cisplatin. In each experiment, animals were treated with varying doses or schedules of SCV‐07 or placebo. OM was scored in a blinded fashion using digital images obtained during the experimental period. Results: We found that SCV‐07 reduced the severity and duration of both acute and fractionated radiation‐induced OM. Similarly, when radiation and chemotherapy were used to induce OM, treatment with SCV‐07 significantly reduced the duration of ulcerative OM. The therapeutic benefit was dependent on both dose and schedule of administration. Conclusion: Taken together, we found SCV‐07 was able to modify the duration and severity of oral mucositis and was dependent on schedule and dose.     

Interleukin‐1 and interleukin‐8 in nicotine‐ and lipopolysaccharide‐exposed gingival keratinocyte cultures

Johnson GK, Guthmiller JM, Joly S, Organ CC, Dawson DV. Interleukin‐1 and interleukin‐8 in nicotine‐ and lipopolysaccharide‐exposed gingival keratinocyte cultures. J Periodont Res 2010; 45: 583–588. © 2010 John Wiley & Sons A/S Background and Objective: Tobacco use is associated with increased periodontal destruction in both cigarette smokers and smokeless tobacco users. Gingival keratinocytes are the first cells in contact with microbial and tobacco components and play a key role in the innate immune response to these agents. The objective of this study was to evaluate the effect of nicotine and bacterial lipopolysaccharide (LPS) alone and in combination on gingival keratinocyte production of interleukin‐1α (IL‐1α) and interleukin‐8 (IL‐8). Material and Methods: Gingival keratinocyte cultures were established from 10 healthy, non‐tobacco‐using subjects. The cells were stimulated for 24 h with 1 μm or 1 mm nicotine and/or 10 μg/mL Escherichia coli or Porphyromonas gingivalis LPS. Interleukin‐1α and IL‐8 proteins were quantified using ELISAs. Results: Compared with untreated cultures, 1 mm nicotine stimulated production of IL‐1α (p < 0.001); E. coli and P. gingivalis LPS increased IL‐8 production (p = 0.0014 and p = 0.0232, respectively). A combination of nicotine and LPS produced the highest cytokine quantities. Amounts of IL‐1α and IL‐8 following 1 mm nicotine and LPS exposure were significantly greater than in untreated cultures (p < 0.001). Interleukin‐8 was also responsive to 0.1 μm nicotine combined with E. coli or P. gingivalis LPS compared with control cultures (p < 0.0001 and p = 0.0029, respectively). Both cytokines tended to be elevated following the combined treatment relative to nicotine or LPS treatment alone. Conclusion: These results demonstrate that nicotine and LPS differentially regulate IL‐1 and IL‐8 production by gingival keratinocytes. Combined treatment tended to elevate cytokine production further, which may have implications for the progression of periodontitis in tobacco users.     

Insulin‐like growth factor‐binding protein‐2 and ‐3 in gingival crevicular fluid

Takenouchi Y, Ohshima M, Yamaguchi Y, Nishida T, Senda N, Idesawa M, Otsuka K, Ito K. Insulin‐like growth factor‐binding protein‐2 and ‐3 in gingival crevicular fluid. J Periodont Res 2010; 45: 803–808. © 2010 John Wiley & Sons A/S Background and Objective: Insulin‐like growth factor‐binding proteins (IGFBPs) are crucial regulators of insulin‐like growth factor (IGF). They enhance or inhibit IGF functions, but also exhibit IGF‐independent effects. In a previous study, we detected, qualitatively, IGFBP‐2 and ‐3 in gingival crevicular fluid using a cytokine antibody array. Here we extended these results using an ELISA to determine the concentrations of IGFBP‐2 and ‐3 in gingival crevicular fluid. In addition, we explored whether the expression of IGFBP‐2 and IGFBP‐3 correlates with periodontal disease severity. Material and Methods: Gingival crevicular fluid samples from 92 sites of 12 patients affected with periodontal disease and from 100 sites of 19 healthy volunteers, were collected, divided into two groups and analyzed by ELISA for IGFBP‐2 and ‐3 expression. The potential correlation among probing depth, gingival index and the concentrations of IGFBP‐2 and ‐3 was analyzed. Results: Positive correlations were observed between the concentration of IGFBP‐2 and probing depth and gingival index, but not for IGFBP‐3. The IGFBP‐2 concentrations at bleeding on probing‐positive sites and at sites with a probing depth of ≥ 4 mm were higher than at bleeding on probing‐negative sites and at sites with a probing depth of ≤ 3 mm. Conclusion: These results indicate that IGFBP‐2 is a potential novel marker for periodontal disease progression. As IGFBP‐2 modulates bone metabolism and cell migration, IGFBP‐2 in the gingival crevicular fluid may reflect periodontal disease activity.     

Dental status and self‐assessed chewing ability in 70‐ and 80‐year‐old subjects in Sweden

The objective was to compare two cohorts of elderly people, 70 and 80 years old, with respect to dental status and self‐assessed chewing ability. The hypotheses were as follows: (i) dental status is associated with self‐assessed chewing ability; (ii) chewing ability is poorer among the 80‐ than the 70‐year‐old subjects. Identical questionnaires were in 2012 sent to all subjects born in 1942 and 1932, living in two Swedish counties. The response rate was 70·1% resulting in samples of 5697 70‐ and 2922 80‐year‐old subjects. Answers to questions on self‐assessed chewing ability, dental status and some other factors have been analysed. Dental status varied but was in general good; 72% of the 70‐ and 60% of the 80‐year‐old subjects reported that they had all or only few missing teeth. Rate of edentulism was 3% and 7%, respectively. Removable partial dentures were reported by 6% and 10%, respectively, implant treatment by 13% in both cohorts. Self‐assessed chewing ability was mostly good and correlated with the number of teeth (Spearman rho = 0·46). A majority of the edentulous subjects assessed their chewing ability as very or fairly good. Logistic regression showed that self‐assessed chewing ability was significantly associated with a number of dental variables but also with general health. In conclusion, dental status was relatively good at both ages but somewhat poorer in the older cohort. Dental status, some other dental variables and being healthy were in both age groups significantly associated with self‐assessed chewing ability.     

Reliability and Failure Modes of Implant‐Supported Y‐TZP and MCR Three‐Unit Bridges

Purpose: Chipping within veneering porcelain has resulted in high clinical failure rates for implant‐supported zirconia (yttria‐tetragonal zirconia polycrystals [Y‐TZP]) bridges. This study evaluated the reliability and failure modes of mouth‐motion step‐stress fatigued implant‐supported Y‐TZP versus palladium‐silver alloy (PdAg) three‐unit bridges. Materials and Methods: Implant‐abutment replicas were embedded in polymethylmethacrylate resin. Y‐TZP and PdAg frameworks, of similar design (n = 21 each), were fabricated, veneered, cemented (n = 3 each), and Hertzian contact‐tested to obtain ultimate failure load. In each framework group, 18 specimens were distributed across three step‐stress profiles and mouth‐motion cyclically loaded according to the profile on the lingual slope of the buccal cusp of the pontic. Results: PdAg failures included competing flexural cracking at abutment and/or connector area and chipping, whereas Y‐TZP presented predominantly cohesive failure within veneering porcelain. Including all failure modes, the reliability (two‐sided at 90% confidence intervals) for a “mission” of 50,000 and 100,000 cycles at 300 N load was determined (Alta Pro, Reliasoft, Tucson, AZ, USA). No difference in reliability was observed between groups for a mission of 50,000. Reliability remained unchanged for a mission of 100,000 for PdAg, but significantly decreased for Y‐TZP. Conclusions: Higher reliability was found for PdAg for a mission of 100,000 cycles at 300 N. Failure modes differed between materials.     

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.