Kirstin Vach

Clinical Outcomes of Zirconia Dental Implants: A Systematic Review

To determine the survival rate and marginal bone loss (MBL) of zirconia dental implants restored with single crowns or fixed dental prostheses. An electronic search was conducted up to November 2015 (without any restriction regarding the publication time) through the databases MEDLINE (PubMed), Cochrane Library, and EMBASE to identify randomized controlled clinical trials and prospective clinical trials including >15 patients. Primary outcomes were survival rate and MBL. Furthermore, the influence of several covariates on MBL was evaluated. Qualitative assessment and statistical analyses were performed. This review was conducted according to preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines for systematic reviews. With the applied search strategy, 4,196 titles could be identified. After a screening procedure, 2 randomized controlled clinical trials and 7 prospective clinical trials remained for analyses. In these trials, a total of 326 patients received 398 implants. The follow-up ranged from 12 to 60 mo. Implant loss was mostly reported within the first year, especially within the healing period. Thereafter, nearly constant survival curves could be observed. Therefore, separate meta-analyses were performed for the first and subsequent years, resulting in an implant survival rate of 95.6% (95% confidence interval: 93.3% to 97.9%) after 12 mo and, thereafter, an expected decrease of 0.05% per year (0.25% after 5 y). Additionally, a meta-analysis was conducted for the mean MBL after 12 mo, resulting in 0.79 mm (95% confidence interval: 0.73 to 0.86 mm). Implant bulk material and design, restoration type, and the application of minor augmentation procedures during surgery, as well as the modes of temporization and loading, had no statistically significant influence on MBL. The short-term cumulative survival rates and the MBL of zirconia implants in the presented systematic review are promising. However, additional data are still needed to confirm the long-term predictability of these implants.

Enterococcus faecalis from Food, Clinical Specimens, and Oral Sites: Prevalence of Virulence Factors in Association with Biofilm Formation

Enterococci have gained significance as the cause of nosocomial infections; they occur as food contaminants and have also been linked to dental diseases. E. faecalis has a great potential to spread virulence as well as antibiotic resistance genes via horizontal gene transfer. The integration of food-borne enterococci into the oral biofilm in-vivo has been observed. Therefore, we investigated the virulence determinants and antibiotic resistance of 97 E. faecalis isolates from the oral cavity, food, and clinical specimens. In addition, phenotypic expression of gelatinase and cytolysin were tested, in-vitro biofilm formation was quantified and isolates were compared for strain relatedness via pulsed field gel electrophoresis (PFGE). Each isolate was found to possess two or more virulence genes, most frequently gelE, efaA, and asa1. Notably, plaque/saliva isolates possessed the highest abundance of virulence genes, the highest levels of phenotypic gelatinase and hemolysin activity and concurrently a high ability to form biofilm. The presence of asa1 was associated with biofilm formation. The biofilm formation capacity of clinical and plaque/saliva isolates was considerably higher than that of food isolates and they also showed similar antibiotic resistance patterns. These results indicate that the oral cavity can constitute a reservoir for virulent E. faecalis strains possessing antibiotic resistance traits and at the same time distinct biofilm formation capabilities facilitating exchange of genetic material.

Clinical and Patient-reported Outcomes of a Zirconia Oral Implant: Three-year Results of a Prospective Cohort Investigation

The objective of this study was to determine the clinical, radiographic, and patient-reported outcomes of a 1-piece alumina-toughened zirconia implant restored with single crowns (SCs) or 3-unit fixed dental prostheses (FDPs) after 3 y of observation. Forty patients received 53 implants, placed in a 1-stage operation with immediate temporization. Finally, 50 implants were restored with 24 SCs and 13 FDPs. To evaluate peri-implant bone loss, standardized radiographs were taken at implant insertion, at final restoration delivery, and after 1 and 3 y. Additionally, several soft tissue parameters and patient-reported outcome measures were evaluated. Linear mixed models with random intercept for each patient and patients as clusters were used to compare subgroups. Three patients did not receive a SC due to early implant loss, and 1 patient died. As a result, 36 patients with 49 implants were followed-up for 3 y, giving a cumulative survival rate of 94.2%. The average marginal bone loss amounted to 0.79 mm (SCs, 0.47 mm; FDPs, 1.07 mm; P < 0.001). After the delivery of the final prosthetic restoration, further bone loss was not statistically significant (0.09 mm; P = 0.700). Probing depth, clinical attachment level, and modified bleeding index increased significantly at the implant sites, whereas gingival recession decreased significantly. Compared with the pretreatment questionnaires, the patient-reported outcome measures showed a permanently improved perception of function, aesthetics, sense, speech and self-esteem. The survival rate of the investigated ceramic implant system seems to be comparable to reported survival rates of titanium implants when immediately restored. The recorded parameters suggest its potential for clinical utilization.

Two-piece zirconia oral implants withstand masticatory loads: An investigation in the artificial mouth.

OBJECTIVE To evaluate the fracture resistance of two-piece zirconia oral implants after long-term thermomechanical cycling in an aqueous environment. Non-loaded samples and a one-piece implant system served as control groups. METHODS A total of 48 zirconia implants were evaluated: 16 one-piece implants (ATZ; Group A) and 32 differently connected two-piece implants (16 screwed, Group B; 16 bonded, Group C) made of Y-TZP-A (implant+abutment; B) and Y-TZP-A/ATZ (implant/abutment; C), respectively. These groups were divided into two subgroups composed of 8 samples. The samples of subgroups 1 (A1, B1, C1) were not exposed to any cyclic loading, whereas subgroups 2 (A2, B2, C2) were loaded with 10 million cycles (98 N). Subsequently, all 48 implants were statically loaded to fracture. RESULTS A constant load on distinct lever arms resulted in different exerted bending moments during the dynamic loading (A2: 23.4Ncm, B2: 17.9 Ncm, C2: 32.3 Ncm). All implants survived the long-term thermomechanical cycling. For the static loading the following average bending moments were calculated: A1/A2: 362/399 Ncm; B1/B2: 398/346 Ncm; C1/C2: 380/252 Ncm. Foregoing dynamic loading significantly increased fracture resistance of Group A implants, whereas Group B/C implants showed significantly decreased values. Potentially owed to the experimental setup in an aqueous environment of 60 °C, 5/8 C2 samples showed mobility between implant and abutment due to debonding after dynamic loading conditions. SIGNIFICANCE The evaluated ceramic implant systems seem to be able to resist physiological chewing forces long-term. Within the limitations of the experimental setup, the connecting mechanism of Group C implants might be a weak point.

Novel Broad-Spectrum Antimicrobial Photoinactivation of In Situ Oral Biofilms by Visible Light plus Water-Filtered Infrared A

ABSTRACT Antimicrobial photodynamic therapy (APDT) has gained increased attention as an alternative treatment approach in various medical fields. However, the effect of APDT using visible light plus water-filtered infrared A (VIS + wIRA) on oral biofilms remains unexplored. For this purpose, initial and mature oral biofilms were obtained in situ; six healthy subjects wore individual upper jaw acrylic devices with bovine enamel slabs attached to their proximal sites for 2 h or 3 days. The biofilms were incubated with 100 μg ml−1 toluidine blue O (TB) or chlorin e6 (Ce6) and irradiated with VIS + wIRA with an energy density of 200 mW cm−2 for 5 min. After cultivation, the CFU of half of the treated biofilm samples were quantified, whereas following live/dead staining, the other half of the samples were monitored by confocal laser scanning microscopy (CLSM). TB- and Ce6-mediated APDT yielded a significant decrease of up to 3.8 and 5.7 log10 CFU for initial and mature oral biofilms, respectively. Quantification of the stained photoinactivated microorganisms confirmed these results. Overall, CLSM revealed the diffusion of the tested photosensitizers into the deepest biofilm layers after exposure to APDT. In particular, Ce6-aided APDT presented elevated permeability and higher effectiveness in eradicating 89.62% of biofilm bacteria compared to TB-aided APDT (82.25%) after 3 days. In conclusion, antimicrobial photoinactivation using VIS + wIRA proved highly potent in eradicating oral biofilms. Since APDT excludes the development of microbial resistance, it could supplement the pharmaceutical treatment of periodontitis or peri-implantitis.

Veneered anatomically designed zirconia FDPs resulting from digital intraoral scans: Preliminary results of a prospective clinical study.

OBJECTIVES The aim of this prospective clinical study was to evaluate the clinical performance of veneered anatomically designed zirconia fixed dental prostheses (FDPs) resulting from intraoral digital impressions. METHODS 24 patients requiring treatment were provided with all-ceramic FDPs. Intraoral scans (iTero) were performed and veneered anatomically designed CAD/CAM-zirconia FDPs (Zerion/VitaVM9) were fabricated. A feldspar veneering ceramic following a slow cooling firing protocol was applied. A self-curing resin based luting material was used for adhesive cementation. Clinical evaluations were performed at baseline and 6, 12, and 18 months recalls according to the modified USPHS-criteria. Intraoral digital surface scans (iTero) were performed at each recall examination and were digitally superimposed (Geomagic) to evaluate potential veneer cohesive fractures. Kaplan-Meier survival analysis comprised secondary caries, clinically unacceptable fractures, root canal treatment and debonding. Kaplan-Meier success rate included restorations with minimal crevices, tolerable color deviations and clinically acceptable fractures. Data were statistically analyzed. RESULTS The Kaplan-Meier survival rate and success rate of the FDPs were 100% and 91.7%, respectively. Clinically acceptable veneer cohesive fractures and crevices at the restoration margin were observed in two patients. These shallow veneer fractures were only detected by overlapping baseline and recall scans. Ceramic surface roughness increased significantly over time (p<0.0001). CONCLUSIONS Veneered zirconia FDPs fabricated from digital intraoral scans showed a favorable clinical performance over an observation period of 18 months. Anatomical zirconia core design and slow cooling firing protocol of the veneering ceramic reduced the incidence of chip fractures to a level that could not be detected clinically. CLINICAL SIGNIFICANCE The digital workflow on the basis of intraoral digital impressions resulted in clinically satisfying outcomes for veneered zirconia FDPs.

Recurrence rate and shift in histopathological differentiation of oral squamous cell carcinoma – A long-term retrospective study over a period of 13.5 years

OBJECTIVE Little information is available as to whether recurrences of oral squamous cell carcinoma (OSCC) show different histopathological grades than the primary tumor and whether postoperative radiotherapy (PORT) influences the grade of differentiation in the case of recurrence. The objective of this study was the evaluation of recurrence rates and change in differentiation. MATERIAL AND METHODS This retrospective, single-institution cohort study included surgically treated OSCC patients over a 13-year period (2000-2013). The relationship among tumor size, lymph node metastases, and recurrence rate of OSCC was investigated. Primary tumor differentiation was compared with differentiation of recurrence. RESULTS A total of 429 patients (277 men and 152 women) were included in this study. Of these, 124 (28.9%) received PORT. The incidence of primary cervical metastases increased significantly with tumor size (p < 0.001). Recurrence developed in 82 patients (19.1%). Stage T1/T2 showed a significantly lower recurrence rate than stage T3/T4 (16.3% vs. 30.2%) (p < 0.01). A total of 23 (30.7%) patients with recurrence showed a change in differentiation. CONCLUSION Increasing primary tumor size correlates with incidence of cervical metastases and recurrence rate. Initial cervical metastases show no effect on recurrence rates. Differentiation of primary tumor does not correlate with the recurrence rate. The majority of recurrences show consistent histopathological grading.

Pre‐clinical endodontic training with artificial instead of extracted human teeth: does the type of exercise have an influence on clinical endodontic outcomes?

AIM To evaluate whether artificial resin teeth could replace extracted human teeth in pre-clinical endodontic training and if this teaching approach influences the outcome of root canal treatment on patients. METHODOLOGY In a pre-clinical training course, students of group 1 (n = 44) performed simulated endodontic exercises on four plastic blocks and three extracted human teeth. Students of group 2 (n = 45) performed their exercises on plastic blocks and artificial resin teeth (Real-T Endo, Acadental, Lenexa, KS, USA). Both groups performed their first root canal treatments on patients in the following term. Radiographs taken during root canal treatment were used for the evaluation of treatment outcome. Distances between the master cone or the root filling and the radiographic apex as well as iatrogenic errors were assessed, and comparisons were made using Fischers exact test. RESULTS In the pre-clinical course root canal treatments performed by students of group 2 were more often classified as acceptable and a higher number of iatrogenic errors were observed in group 1. When root canal treatments were performed on patients for the first time, no significant difference was observed between the groups in terms of radiographic technical quality of root fillings. CONCLUSIONS The application of artificial teeth instead of extracted human teeth had no effect on the technical quality of root fillings in terms of position in relation to the root apex or the creation of aberrations.

CAD/CAM-fabricated ceramic implant-supported single crowns made from lithium disilicate: Final results of a 5-year prospective cohort study

BACKGROUND All-ceramic bilayer systems suffer from technique-sensitivity, resulting in increased technical complication rates. This might be overcome by monolithic reconstructions, facilitating digital workflows. PURPOSE To evaluate the clinical and patient-reported outcome of CAD/CAM-fabricated implant-supported single crowns (ISCs) made of lithium disilicate (LS2 ) cemented on ceramic implants 5 years after implant installation. MATERIALS AND METHODS Twenty-four patients were included in the study. All participants received a one-piece ceramic implant in anterior (4 incisors) and posterior regions (10 premolars, 10 molars). LS2 crowns were computer-aided designed (CAD), manufactured (CAM) and adhesively luted onto the implants. Follow-ups were performed yearly up to 60 months after implant installation. The survival/success rates of the restorations were calculated according to modified US Public Health Service criteria as follows: Clinically relevant defects that could be repaired intraorally were accepted for survival, whereas small-area chippings, roughness (ø < 2 mm), slightly soundable marginal gaps, minimal undercontours/overcontours, and tolerable color deviations were accepted for success. Kaplan-Meier plots were used for the success/survival analyses. Furthermore, patient-reported outcome measures (PROMs) were assessed by applying visual analog scales (VAS). Linear (PROMs) and logistic (USPHS criteria) mixed models were fitted to evaluate time effects on response variables. RESULTS Twenty-two ISCs could be evaluated 55.2 ± 4.2 months after prosthetic delivery. Two patients were reported as drop-outs (1 died, 1 moved abroad). No failures were observed, resulting in 100% survival. At two ISCs, a major-roughness had to be treated. This resulted in a Kaplan-Meier success estimate of 91.7% (95%CI: 70.6%-97.9%). Compared with pretreatment, all surveys at prosthetic delivery except for self-esteem (P = .375) showed significantly improved VAS scores. No decrease in satisfaction could be observed over time until the end of follow-up (P ≥ .056). CONCLUSION Concerning survival/success rates and PROMs, the evaluated crown-implant system showed favorable mid-term results. To date, there are no comparable data available for implant-supported ISCs made of LS2 .

Training of Dental Professionals in Motivational Interviewing can Heighten Interdental Cleaning Self-Efficacy in Periodontal Patients

Background: The success of periodontal therapy depends on the adherence of patients to professional recommendations. The aim of this study was to investigate the influence of a workshop in motivational interviewing (MI) on non-surgical periodontal treatment performed by dental students. Materials and Methods: In the experimental group patients with periodontitis were treated by students trained in MI, while in the control group patients were treated by students who had not been trained in MI. Clinical oral parameters were assessed by a blinded periodontist in addition to the evaluation of psychological questionnaires given before and after the non-surgical periodontal treatment (6 months). Conversations between patients and students were recorded and rated with the Motivational Treatment Integrity Code (MITI-d) by a blinded psychologist. Results: There were 73 patients in the MI group and 99 patients in the control group. The MI group showed significantly higher scores in the MITI-d analysis. Regression analysis showed that there were no significant differences between groups with regard to plaque level, gingival bleeding, pocket depth reduction or bleeding upon probing. However, patients in the MI-group showed significantly higher interdental cleaning self-efficacy than patients in the control group (MI = 19.57 ± 4.7; control = 17.38 ± 6.01; p = 0.016). Conclusion: Teaching MI to dental students resulted in a significant improvement in the self-efficacy of interdental cleaning in patients compared to a control group of non-trained students, but no improvement in other aspects of non-surgical periodontal therapy. The study also showed that an 8-h workshop with supervision significantly improved the MI-compliant conversations of dental students without requiring more conversation time.