Implant survival in mandibles of irradiated oral cancer patients.

OBJECTIVE: The aim of this study was to analyze long-term implant survival in the mandible after radiotherapy and radical surgery in oral cancer patients. STUDY DESIGN: Between 1990 and 2003, 71 patients (15 females, 56 males; average age 57.8 years, range 16-84.1 years) were treated with dental implants after radiochemotherapy and ablative surgery of oral cancer. Radiation therapy was delivered in daily fractions of 2 Gy given on 25 days (total dose of 50 Gy). Oral defects were reconstructed microsurgically with jejunal, iliac crest or radial forearm grafts. Thereafter 316 dental implants were placed in the non-irradiated residual bone (84; 27%), irradiated residual bone (154; 49%) or grafted bone (78; 25%) at various intervals (mean interval 1.41 (+/- 1.01) years, range 0.34-6.35 years). RESULTS: The mean follow-up time after implant insertion was 5.42 (+/- 3.21) years (range 0.3-13.61 years). The overall 2-, 3-, 5-, and 8-year survival rates of all implants were 95%, 94%, 91% and 75%. Forty-four implants were lost in 21 patients during the observation period. Irradiation of the mandibular bone showed significantly (P = 0.0028) lower implant survival compared with non-irradiated mandibular bone. The 8-year survival rate in the non-irradiated residual bone (two loss), irradiated residual bone (29 loss) or grafted bone (13 loss) were 95%, 72% and 54%, respectively. Time of implantation after irradiation showed no statistically significant influence. Implant brand, length or diameter or the incidence of resective surgery on the mandible and gender of patients had no statistically significant influence on implant survival. CONCLUSION: Radiation therapy with 50 Gy was significantly related to shorter implant survival in mandibular bone. Survival was lowest in grafted bone. Time of implant placement had no statistically significant influence on survival under the conditions of this study. Although implant survival is lower in irradiated mandibles, implants significantly facilitate prosthodontic treatment and enhance outcome of oral rehabilitation in cancer patients.

Periodontitis, a marker of risk in pregnancy for preterm birth.

BACKGROUND: Why chronic periodontitis may induce an inflammatory response with premature pregnancy termination is unclear. AIMS: (1) To assess if periodontitis predicts premature gestation; (2) to study amniotic fluid cytokines and periodontitis variables in early-stage pregnancy. MATERIAL AND METHODS: A periodontal examination and collection of amniotic fluid was performed (weeks 15-20) of pregnancy in 36 women at risk for pregnancy complications. Amniotic fluid (bacteria), vaginal smears and intra-oral plaque samples were studied. Cytokine levels in amniotic fluid were studied in relation to other study variables. RESULTS: Periodontitis was diagnosed in 20% of normal and in 83% of preterm birth cases (p<0.01). Bacteria were never found in the amniotic fluids studied. Sub-gingival plaque samples including bacteria in the orange and red complexes were found in 18% of full-term 100% of preterm cases (p<0.001) and total colony-forming units (CFUs) were higher in preterm birth (p<0.01). Amniotic levels of interleukin (IL)-6 and prostaglandin-E2 (PGE2) were higher in preterm cases (p<0.001). Amniotic IL-6 (r=0.56, p<0.01) and PGE2 (r=0.50, p<0.01) cytokine levels were correlated with CFU from sub-gingival plaque samples (r2=0.44). The odds ratio of preterm delivery and having periodontitis was 20.0 (95% confidence interval (CI): 2.0-201.7, p<0.01). The odds of >60 CFU in sub-gingival plaque and preterm birth was 32.5:1 (95% CI: 3.0-335.1, p<01). CONCLUSIONS: Pregnant women with findings of elevated amniotic fluid levels of PGE2, IL-6 and IL-8 in the 15-20 weeks of pregnancy and with periodontitis are at high risk for premature birth. The implication of this is that periodontitis can induce a primary host response in the chorioamnion leading to preterm birth.

Effect of low-power laser irradiation on bony implant sites.

This study was designed to examine the effects of low-energy laser irradiation on osteocytes and bone resorption at bony implant sites. Five male baboons with a mean age of 6.5 years were used in the study. Four holes for accommodating implants were drilled in each iliac crest. Sites on the left side were irradiated with a 100 mW low-energy laser (690 nm) for 1 min (6 Joule) immediately after drilling and insertion of four sandblasted and etched (Frialit-2 Synchro) implants. Five days later, the bone was removed en bloc and was evaluated histomorphometrically. The mean osteocyte count per unit area was 109.8 cells in the irradiated group vs. 94.8 cells in the control group. As intra-individual cell counts varied substantially, osteocyte viability was used for evaluation. In the irradiated group, viable osteocytes were found in 41.7% of the lacuna vs. 34.4% in the non-irradiated group. This difference was statistically significant at P < 0.027. The total resorption area, eroded surface, was found to be 24.9% in the control group vs. 24.6% in the irradiated group. This difference was not statistically significant. This study showed that osteocyte viability was significantly higher in the samples that were subjected to laser irradiation immediately after implant site drilling and implant insertion, in comparison to control sites. This may have positive effects on the integration of implants. The bone resorption rate, in contrast, was not affected by laser irradiation.

Freeze-dried bone for maxillary sinus augmentation in sheep. Part II: biomechanical findings.

This study examines the biomechanical loading capacity of dental implants placed in the posterior maxilla in conjunction with subantral augmentation with either homogeneous demineralized freeze-dried bone from sheep (s-DFDB) or heterogeneous demineralized freeze-dried human bone (h-DFDB) as grafting material in sheep. In 36 adult female mountain sheep, the Schneiderian membrane was elevated extraorally in both maxillary sinuses, and two titanium plasma-flame-sprayed cylindrical implants were inserted in each lateral antral wall. Three groups of 18 maxillary sinuses each were augmented with s-DFDB, h-DFDB and autogenous bone from the illiac crest, respectively. In the remaining 18 sinuses, the subantral hollow space was left empty. Pull-out tests were carried out after intervals of 12, 16 and 26 weeks. The mean pull-out force needed, irrespective of time, was 259.3 N in the empty control group, 356.7 N in the group augmented with autogenous bone, 278.1 N in the test group augmented with h-DFDB and 365.2 N in the group augmented with s-DFDB, revealing no significant difference between the individual groups (P > 0.05). The implants of the group augmented with autogenous bone showed an increase in the mean pull-out force from 223.8 N after 12 weeks to 523.7 N after 26 weeks. The nonaugmented control group yielded values of 248 N after 12 weeks, which rose to 269.8 N at the last test, while the values of the h-DFDB group increased from 275.4 N to 325.4 N. The highest initial pull-out values were obtained in the s-DFDB group. They amounted to 310.5 N after 12 weeks and rose to 481.4 N after 26 weeks. Time thus proved to have a significant influence on the pull-out forces (P = 0.014) with a statistically proven linear trend (P = 0.007). The findings of this experimental study indicate that the use of homogeneous DFDB in one-stage sinus lift procedures results in a mechanical loading capacity of implants comparable to that achieved by autogenous cancellous bone from the iliac crest. In contrast, the use of heterogenous-DFDB resulted in only slightly higher pull-out forces than those observed in the nonaugmented control group after 26 weeks.