Stefan Wolfart

Survival probability of zirconia-based fixed dental prostheses up to 5 yr: a systematic review of the literature.

The purpose of this systematic review was to calculate the 5-yr survival rates of all-ceramic zirconia-based fixed dental prostheses (FDPs) and to analyze technical and biological complications. An electronic literature search of MEDLINE (PubMed) was conducted independently by three reviewers to identify clinical studies from 1999 to 2009 and was completed by a manual search. Keywords and inclusion and exclusion criteria were well-defined. The search revealed 399 titles and led to the final analysis of 18 full-text articles. Nine studies met the inclusion criteria. Extracted data were statistically calculated into 5-yr survival rates and 5-yr complication-free rates by using Poisson regression analysis. In total, 310, 3- to 4-unit FDPs and 20 FDPs with more than 4 units were included. The estimated 5-yr survival rate for all FDPs was 94.29% (95% CI: 58.98-99.32); 19 FDPs were lost as a result of catastrophic failures. The 5-yr complication-free rate regarding technical complications was 76.41% (95% CI: 42.42-91.60) with chipping being the most frequent complication. Regarding biological complications, the 5-yr complication-free rate was 91.72% (95% CI: 59.19-98.53). The survival rates of zirconia-based short-unit FDPs are promising. However, an important improvement of the veneering systems is required, and for FDPs with more units in function, further randomized, controlled clinical trials are necessary.

Implant–abutment interface design affects fatigue and fracture strength of implants

OBJECTIVES Failures of implant-abutment connections are relatively frequent clinical problems. The aim of this study was to evaluate the influence of long-term dynamic loading on the fracture strength of different implant-abutment connections. MATERIAL AND METHODS Six implant systems were tested: two systems with external connections (Brånemark, Compress) and four systems with internal connections (Frialit-2, Replace-Select, Camlog, Screw-Vent). Fracture strength was tested in two subgroups for each system: one subgroup with (dyn) and the other without prior dynamic loading (contr). Each subgroup consisted of eight specimens with standard implant-abutment combinations for single molar crowns. Dynamic loading was performed in a two-axis chewing simulator with 1,200,000 load cycles at 120 N. RESULTS Median fracture strengths in Newton (N) and 25th and 75th percentiles [in brackets] were: Brånemark: dyn=729 [0;802]/contr=782 [771;811], Frialit-2: dyn=0 [0;611]/contr=887 [798;941], Replace-Select: dyn=1439 [1403;1465]/contr=1542 [1466;1623], Camlog: dyn=1482 [1394;1544]/contr=1467 [1394;1598], Screw-Vent: dyn=0 [0;526]/contr=780 [762;847] and Compress: dyn=818[0;917]/contr=1008 [983;1028]. In some dyn subgroups, failures of the implant-abutment connection occurred already during dynamic loading: three specimens of the Brånemark and Compress groups and six specimens of the Screw-Vent and the Frialit-2 groups failed during dynamic loading. Statistically significant differences (P< or =0.05) in fracture strength could be found between groups with different connection designs. CONCLUSION Implant systems with long internal tube-in-tube connections and cam-slot fixation showed advantages with regard to longevity and fracture strength compared with systems with shorter internal or external connection designs.

The clinical accuracy of single crowns exclusively fabricated by digital workflow—the comparison of two systems

ObjectivesThe purpose of the study was to compare the accuracy of crowns exclusively fabricated by the digital workflow of two systems. The null hypothesis stated was: Both systems do not differ with respect to marginal and internal accuracy.Materials and methodsIn 14 patients, 13 molars and 1 premolar were prepared. Each preparation was scanned intraorally with two different digital impression systems, Lava COS and Cerec AC. On the basis of these data, Lava DVS crowns [DVS] and Vita Rapid Layering Technique crowns [RLT] were fabricated, respectively. Both systems contained of a zirconia framework and a digitally fabricated silicate ceramic veneering. The marginal and internal fit of the crowns was documented by a replica technique. The replicas were examined under microscope with a magnification of ×200. The Wilcoxon signed rank test was applied in order to test if the values of the two systems showed significant differences at p ≤ 0.05.ResultsThe results were as follows in micrometers (±standard deviation): at the marginal gap, 51 (±38) for [DVS] and 83 (±51) for [RLT]; mid-axial, 130 (±56) for [DVS] and 128 (±66) for [RLT]; axio-occlusal, 178 (±55) for [DVS] and 230 (±71) for [RLT]; and centro-occlusal, 181 (±41) for [DVS] and 297 (±76) for [RLT]. According to the Wilcoxon signed rank test, the results differed significantly at the marginal, axio-occlusal, and centro-occlusal gaps.ConclusionsThe null hypothesis had to be rejected.Clinical relevanceThe exclusively digital workflow on the basis of intraoral digital impressions delivered clinically satisfying results for single crowns with both systems.

Clinical outcome of three-unit lithium-disilicate glass-ceramic fixed dental prostheses: up to 8 years results.

OBJECTIVES The purpose of this prospective study was to evaluate the clinical outcome of crown-retained fixed dental prostheses (FDPs) made from a lithium-disilicate glass-ceramic (IPS e.max Press, Ivoclar-Vivadent). METHODS Thirty-six three-unit FDPs were placed in 28 patients. The FDPs replaced teeth in the anterior (16%) and posterior (84%) regions. All teeth were prepared following a standardized protocol. The size of the proximal connector of the FDPs was 12 mm2 (anterior) or 16 mm2 (posterior). FDPs were cemented either with glass-ionomer cement (n=19) or composite resin (n=17). The following parameters were evaluated at baseline, 6 months after cementation and then annually (at abutment and contralateral teeth): probing pocket depth, plaque index, bleeding on probing, and tooth vitality. RESULTS Three FDPs were defined as drop-out. The mean observation period of the remaining 33 FDPs was 86 months (range: 67-98 months): two FDPs in two patients had to be replaced (6%) because of fractures. The 8-year survival rate according to Kaplan-Meier was 93%. In addition, chipping of the veneering material was found in two FDPs (6%). Two abutments (3%) of two restorations had to be treated endodontically; and two FDPs (6%) lost retention and had to be recemented. These complications did not affect the function of the involved restorations clinically. There were no significant differences between the periodontal parameters of the test and control teeth. SIGNIFICANCE Short-span crown-retained three-unit FDPs made from lithium-disilicate glass-ceramic can be used clinically irrespective of an adhesive or conventional cementation.

Facial attractiveness: visual impact of symmetry increases significantly towards the midline.

Symmetry is thought to be a major prerequisite for an attractive face. Many faces are not symmetric, yet are still regarded as beautiful. What role, then, does asymmetry play in the perception of beauty? We studied the assessment of computer-manipulated images by independent judges (n = 200–250): part A: nevi located at different positions; part B: standardized changes of the orbital region. The results showed that slight lateral orbital and facial asymmetry does not impair attractiveness at all and that asymmetries close to the midline are significantly less attractive than those affecting the lateral aspect of the face (P < 0.001). A single nevus which is located laterally on the face is significantly more attractive than a nevus close to the midline (P < 0.001). Faces with a completely symmetric bilateral pair of nevi in the same lateral positions (perceived as attractive when alone), received the worst ratings (P < 0.001). Symmetry is a characteristic of the attractive face, but there are exceptions to the rule. Under certain conditions symmetry can be completely unattractive. The visual impact of symmetry on the perception of beauty increases significantly when approaching the midline.

Four-year clinical results of fixed dental prostheses with zirconia substructures (Cercon): end abutments vs. cantilever design.

The purpose of this prospective study was to evaluate the clinical outcome of three- to four-unit posterior all-ceramic fixed dental prostheses (FDPs) made of yttria-stabilized tetragonal zirconia-polycrystal ceramic frameworks (CerconBase; Degudent). Fifty-eight restorations were placed in 48 patients. Twenty-four FDPs had an end abutment design (EAD) replacing 3 premolars and 21 molars. Thirty-four FDPs had a cantilever design (CD) replacing 11 premolars and 23 molars. The frameworks had a minimum proximal connector dimension of 3 x 3 mm. The fixed dental prostheses were cemented with glass-ionomer cement after air-abrading the inner crown surfaces. Three FDPs were defined as drop-outs. The mean observation period was 48 +/- 7 months for the EAD (21 patients/24 FDPs) and 50 +/- 14 months for the CD (25 patients/31 FDPs). The 4-yr survival rate, according to the Kaplan-Meier analyses, was 96% for the EAD and 92% for the CD. The technical complication rate was 13% for the EAD and 12% for the CD, and the biological complication rate was 21% for the EAD and 15% for the CD. For none of the analyses were significant differences found between both groups. After 4 yr the clinical outcome of three- to four-unit posterior FDPs with EAD and CD was promising.

Influence of Contamination on Zirconia Ceramic Bonding

The removal of contaminants prior to the bonding of ceramics is critical for the clinical success of a long-term durable resin bond. This study tested the null hypotheses that there are no contaminants on the zirconia ceramic surface left after try-in simulation, and there are no influences of contamination and cleaning methods on zirconia ceramic bonding durability with 10-methacryloyloxy-decyl dihydrogenphosphate-containing composite resins. After saliva immersion and the use of a silicone disclosing agent, airborne-particle-abraded ceramic specimens were cleaned with acetone, 36% phosphoric acid, additional airborne-particle abrasion, or only water spray. Chemical analyses of specimen surfaces were performed by x-ray photoelectron spectroscopy. The influences of contamination and cleaning methods on ceramic bond durability were examined by tensile testing after 3 or 150 days’ water storage with 37,500 thermal cycles. Contamination, existing after try-in simulation as confirmed by chemical analysis, significantly reduced zirconia ceramic-resin bonds. Airborne-particle abrasion may be the most effective cleaning method.

Zirconia ceramic inlay-retained fixed dental prostheses ― first clinical results with a new design

OBJECTIVES The purpose of this prospective study was to evaluate the clinical outcome of inlay-retained fixed dental prostheses (IRFDPs) with a new design made from a zirconia ceramic. METHODS Twenty-three 3-unit IRFDPs were placed in 23 patients, restoring five second premolars and 18 first molars. Preparations were performed in accordance with general principles for ceramic inlay restorations and modified with a retainer-wing bevel preparation in the enamel at the buccal and oral sides. The frameworks were scanned and milled out of zirconia ceramic, using the InLab CAD/CAM-system and the pontics were veneered with feldspathic ceramic. All IRFDPs were luted adhesively with composite resin. Clinical follow-up examinations were performed annually. Statistical analysis was performed using descriptive statistics and Kaplan-Meier survival analysis. RESULTS All patients with their 23 IRFDPs could be examined clinically after a mean observation time of 20 months. None of the IRFDPs failed. Two ceramic veneers fractured, both of them needed repair. One restoration debonded, but was recemented immediately. However, these technical complications did not affect the clinical function of the IRFDPs involved. CONCLUSIONS The clinical outcome of zirconia ceramic IRFDPs with the modified design seems promising.

Gender and Nasal Shape : Measures for Rhinoplasty

Background: Gender-specific nasal shapes are recommended for rhinoplasty. This study was conducted to clarify whether there truly are gender-related differences and to determine optimal nasal shapes in a Caucasian population. Methods: The authors created female and male composite photographs of “average” (n = 128 each), “optimal” (n = 16 each), and “most unpleasant” (n = 8 each) noses stratified on the basis of each photographed subject’s (n = 311) own evaluation of the attractiveness of her or his nose, using a visual analogue scale. These composites were also assessed by 308 independent judges. Results: Optimal female noses showed a horizontally and vertically lower nasion and were concave to straight in profile as compared with optimal male noses, which had a vertically and horizontally higher nasion and a straight profile. A supratip break was not found in any of the composites. At least half of the judges rated average and optimal male composite noses as female. A significant majority mistook the composite of the most unpleasant female noses as male (frontal view, 62.0 percent; lateral view, 72.4 percent; p < 0.001). Optimal and average female and male noses were found to be independently significantly more attractive than the most unpleasant ones (p < 0.001, n = 308 judges). Women and men with a straight or concave profile were significantly (p = 0.017 and p = 0.006, respectively) more satisfied with the appearance of their nose than those with nasal humps. Conclusions: Gender-related differences in nasal shape appear to be subtle, with nasion position being one of the main factors. A nasal hump and a supratip break are not desirable.

Recent advances of ultrasound imaging in dentistry – a review of the literature

Ultrasonography as an imaging modality in dentistry has been extensively explored in recent years due to several advantages that diagnostic ultrasound provides. It is a non-invasive, inexpensive, painless method and unlike X-ray, it does not cause harmful ionizing radiation. Ultrasound has a promising future as a diagnostic imaging tool in all specialties in dentistry, for both hard and soft tissue detection. The aim of this review is to provide the scientific community and clinicians with an overview of the most recent advances of ultrasound imaging in dentistry. The use of ultrasound is described and discussed in the fields of dental scanning, caries detection, dental fractures, soft tissue and periapical lesions, maxillofacial fractures, periodontal bony defects, gingival and muscle thickness, temporomandibular disorders, and implant dentistry.