10-Year Clinical Comparative Study of Ceramic and Composite Veneered Metal Crowns

The rejection of composite veneerings in fixed partial dentures is primarily caused by the inadequacy of the bonds between the metal framework and the composite veneering. The development of improved veneering composites necessitates an investigation of their clinical suitability compared with ceramic materials. Nineteen patients with at least two suitable, adjacent natural teeth for crowning were treated with 64 high noble alloy crowns. The adjacent crowns were veneered with ceramic (IPS inline) and composite materials (SR Adoro). Seven follow-up examinations were carried out over a period of 10 years. The crowns were investigated for mechanical defects, periodontal parameters, and discolorations. The survival rates of the ceramic veneered metal crowns (CeMCs) and composite veneered metal crowns (CoMCs) at the 10-year follow-up were 87.1 and 87.9%, respectively. The success rates of the crowns after 10 years were 83.9% for CeMCs and 51.5% for CoMCs (log-rank test, p = 0.009). No significant differences between the groups were found in the periodontal parameters (Kruskal-Wallis one-way analysis of variance, ANOVA p ⟩ 0.05). After 10 years, discoloration patterns of the two materials differed significantly (Mann-Whitney-U-test, p = 0.017). Thus, despite the improvements associated with CoMCs, CeMCs remain the gold standard for veneered metal crowns.

Contact allergies to dental materials

There is a lack of epidemiological data on allergies to dental materials. For example, in the recently published fifth German Oral Health Study (DMS V), no information was given on any common allergies or allergies to dental materials. The aim of the present observational study was therefore to determine the frequencies and symptoms of allergies to dental materials. A public consultation hour for allergies of the oral mucosa and material incompatibilities has been integrated in the Department of Dental Prosthodontics and Materials Science in Leipzig, where clinical patient data have systematically been collected since 2012. The objective mucosal findings and the patients’ complaints are documented in detail in a specifically designed data sheet. This study included 86 subjects (83.7% women and 16.3% men) with oral symptoms of a contact allergy. The average age was 63 years (24–86). The most common allergies were to metals, of which nickel and cobalt were the most common allergens. Furthermore, many allergies were indicated to ingredients of cosmetics and composites. Allergies to components in methacrylate-containing denture resins came in at rank 5. 52.4% of the patients showed mucosal changes. Contact stomatitis (54.5%) and an oral lichenoid lesion (20.5%) were most frequently diagnosed. 86% of the patients reported subjective complaints. Pain and burning sensations in the mouth were mostly reported. Appropriate dental allergy history, clinical examination of the oral cavity for changes in the oral mucosa, analysis of specific dentures, and screening for psychogenic disorders are necessary to clarify the origin of these symptoms.

Shade Stability of Polymer Infiltrated and Resin Nano Ceramic Crowns after Dynamic Chewing Simulation

OBJECTIVE

Investigation of the shade stability of polymer-infiltrated and resin nano ceramic crowns before and after artificial aging.

METHOD

40 identical crowns of each of the materials VITA Enamic (VE) and Lava Ultimate (LU) were manufactured. Half of the crowns went through a dynamic chewing simulation (CS) with thermocycling. Material subgroups: 1. VE, 2. VE/CS, 3. LU, 4. LU/CS (each n=20). These were divided into 4 groups (n=5) and distributed in usual stain solutions. The shade of each crown was measured occlusally and vestibularly before and after insertion using a spectrophotometer (n=5). The data were analyzed using ANOVA and Tukey's test (p≤0.05).

RESULTS

Sum scores (SSC) of the occlusal ΔE values: LU/CS: 7.99, VE: 5.75 VE/CS: 5.44, LU: 5.17. The total sum of the SSC yielded, for the materials: SSCtotal(VE): 20.0 and SSCtotal(LU): 24.0.

SIGNIFICANCE

Occlusally, there were significant shade differences for VE/CS (p=0.025) and LU/CS (p=0.014) between red wine and distilled water. LU/CS is significantly more clearly stained occlusally by coffee in comparison to the other three material subgroups (VE: p=0.007, LU: p=0.026, VE/CS: p=0.013).

CONCLUSIONS

The shade stability of VITA Enamic crowns is superior to that of Lava Ultimate crowns. Only Lava Ultimate is affected by chewing simulation.

Shade Stability of Polymer-Infiltrated and Resin Nano Ceramics

BACKGROUND

The esthetics plays an increasingly significant role in today's dentistry.

OBJECTIVE

The objective was to investigate the shade stability of a polymer-infiltrated and a resin nano ceramic in comparison to a conventional feldspar ceramic and an acrylate polymer.

METHODS

20 specimens of each of the materials, CAD-Temp (CT), Mark II (M), VITA Enamic (VE) and Lava Ultimate (LU), were prepared using the standard method. These were divided into groups (n=5) and placed in the following stain solutions: Distilled water, coffee, Coca-Cola and red wine for 14 days. The shade of each specimen was measured before and after using a spectrophotometer (n=5). The data were analyzed using ANOVA and Tukey's test (p ≤ 0.05).

RESULTS

The largest ΔE mean values were observed in CT by Coca-Cola (4.38 ± 0.41), in M by coffee (5.95 ± 0.62), in VE (6.02 ± 0.78) and LU (8.61 ± 0.30) by red wine. LU had the largest and strongest overall shade differences (total score: SSC=16.95) and CT the least (SSC=8.74). Overall shade differences of VE (SSC=12.03) and M (SSC=12.48) were statistically indistinguishable. After 14 days, only Coca-Cola caused clinically relevant shade differences in CT (ΔE > 2.7); this was also caused by coffee, Coca-Cola and red wine in M and coffee and red wine in VE and LU.

CONCLUSION

On average, VE showed fewer shade differences than LU. After 14 days of immersion, shade differences which exceeded the clinical acceptance threshold of ΔE=2.7 were shown by CT in Coca-Cola, by M in coffee, Coca-Cola and red wine, and by VE and LU in coffee and red wine.

Clinical comparison of liquid-based and conventional cytology of oral brush biopsies: a randomized controlled trial

Background

Exfoliative cytology performed on oral brush samples can help dentists to decide, whether a given oral lesion is (pre-) malignant. The use of non-invasive brush biopsies as an auxiliary tool in the diagnosis of oral mucosal lesions has gained renewed interest since improvements in cytological techniques such as the development of adjuvant diagnostic tools and liquid-based cell preparation techniques.

Methods

The aim of this study was to compare the quality of two different preparation techniques (cell collectors): the conventional transfer procedure to glass slides and the so-called liquid-based cytology preparation method. Cell smears were collected from 10 orally healthy individuals (mean age: 24 years) from the palatine mucosa at two different times (baseline and 4 weeks later). Slides of both techniques were stained by Giemsa (n = 40) and May-Gruenwald Giemsa (n = 40). The statistical analysis was performed with Excel.

Results

On specimen analysis, the liquid-based cytology showed statistically significant improvement compared to conventional glass sides (p < 0.001). Thin layers, which were performed by liquid-based cytology showed significantly better results in the parameters (p < 0.001): uniform distribution, cellular overlapping, cellular disformation, mucus, microbial colonies and debris. The conventional glass slides approach showed more cell overlapping and contamination with extraneous material than thin layers, which were performed by Orcellex® Brush cell collectors.

Conclusions

Both techniques are diagnostically reliable. The liquid-based method showed an overall improvement on sample preservation, specimen adequacy, visualization of cell morphology and reproducibility.

Liquid-based cytology simplifies cell collection due to easier handling and less transfer errors by dentists.

Biomechanical properties of polymer-infiltrated ceramic crowns on one-piece zirconia implants after long-term chewing simulation

Background

Implant and superstructure provide a complex system, which has to withstand oral conditions. Concerning the brittleness of many ceramics, fractures are a greatly feared issue. Therefore, polymer-infiltrated ceramic networks (PICNs) were developed. Because of its high elastic modulus, the PICN crown on a one-piece zirconia implant might absorb forces to prevent the system from fracturing in order to sustain oral forces. Recommendations for the material of superstructure on zirconia implants are lacking, and only one study investigates PICN crowns on these types of implants.

Accordingly, this study aimed to examine PICN crowns on one-piece zirconia implants regarding bond strength and surface wear after long-term chewing simulation (CS).

Methods

Twenty-five hybrid ceramic crowns (Vita Enamic, Vita Zahnfabrik) were produced using computer-aided design/computer-aided manufacturing (CAD/CAM) technology and adhesively bonded (RelyX™ Ultimate, 3M ESPE) to zirconia implants. Twenty of the specimens underwent simultaneous mechanical loading and thermocycling simulating a 5-year clinical situation (SD Mechatronik GmbH). Wear depth and wear volume, based on X-ray micro-computed tomography volume scans (Skyscan 1172-100-50, Bruker) before and after CS, were evaluated.

All crowns were removed from the implants using a universal testing machine (Z010, Zwick GmbH&Co.KG). Subsequently, luting agent was light microscopically localized (Stemi 2000-C, Zeiss).

With a scanning electron microscope (SEM, Phenom™ G2 pro, Phenom World), the area of abrasion was assessed.

Results

After CS, none of the tested crowns were fractured or loosened.

The maximum vertical wear after CS was M = 0.31 ± 0.04 mm (mean ± standard deviation), and the surface wear was M = 0.74 ± 0.23 mm³.

The pull-off tests revealed a 1.8 times higher bond strength of the control group compared to the experimental group (t(23) = 8.69, p < 0.001).

Luting agent was mostly located in the crowns, not on the implants.

The area of abrasion showed avulsion and a rough surface.

Conclusions

PICN on one-piece zirconia implants showed high bond strength and high wear after CS.

[Not Available]

Allergen-triggered lichenoid oral mucosa lesions may occur both in oral lichen planus (OLP) and oral lichenoid lesions (OLL). Clinically, OLP and OLL are difficult to distinguish from each other. An OLP should be checked by histological examination. Therefore all patients with OLP should be included into a close control interval due to the the potential malignant transformation, whereas in the literature a higher risk of malignancy is attributed to OLL in comparison with OLP. Based on a clinical case, it is demonstrated that an interdisciplinary approach in allergy and mucous diagnosis is necessary to verify the correaltion between a contact allergy to amalgam and the lichenoid mucosal lesions. The subsequent treatment exemplifies the steps of dental therapies with multiple contact allergies to dental materials.

Influence of tongue position on the determination of tooth shade

STATEMENT OF PROBLEM

Dentists frequently use electronic devices to determine tooth color. However, neither the instructions for these devices nor the accompanying brochures refer to the environmental conditions required at the point of measurement.

PURPOSE

The purpose of this multicenter prospective clinical study was to reveal whether a change in the oral background influences tooth color determination.

MATERIAL AND METHODS

Students (N=42) at the dental clinic in Berlin, Leipzig, Greifswald and Olomouc (women n=27, men n=15) participated in this study. It was their first contact with the spectral photometer (Easyshade Advance 4.0; VITA Zahnfabrik). After a short introduction on how to use the device, the students made 1-point measurements on the same patient on the maxillary central incisor. In the first measurement, the patient's mouth was open, and the palatal surface uncovered. In the second measurement, the patient's mouth was closed slightly, and the tongue pressed on the lingual surface of the maxillary central incisor. The mean ±SD and the 95% confidence interval (95 % CI) were calculated using the Student t test for each test series (α=.05).

RESULTS

Statistical evaluation of the 2 measurements revealed changes in the L*a*b* values with a mean L*=0.204, a*=-0.351, and b*=0.02; a median of 0.4, -0.3, and -0.1, respectively; a ±SD of 2.37, 0.64, and 0.89, respectively; and 95% CIs of L*=-0.476 to 0.884, a*=-0.531 to -0.702, and b*=-0.23 to 0.52, respectively. These differences were not statistically significant (P>.05). The measurements of L*, a*, and b* with and without tongue coverage of the lingual surfaces of the maxillary teeth did not show any statistically significant differences (P=.663).

CONCLUSIONS

The results demonstrate that the position of the tongue does not influence measurement accuracy during the application of the Easyshade Advance device.

Development and implementation of the Clinical Tooth Shade Differentiation Course--an evaluation over 3 years

OBJECTIVE

Tooth shade differentiation concerns the identification and classification of tooth shades. The objective of this project was to implement the Clinical Tooth Shade Differentiation Course in the preclinical stage of studies and to evaluate the students' perspective over a period of 3 years.

METHODOLOGY

The course is planned for a duration of 10 weeks with two 45-minute sessions per semester week. The entire attendance time was 10:15 h. 2 lectures of 90 minutes each, 2 seminars of 60 min each and 2 teaching units with the phantom head and role playing took place. In addition to the various parameters of tooth shade, changes in tooth shade and the basics of dental esthetics, clinical procedures for manual and digital tooth shade determination were explained and practiced. 96% (69 of 72) of the students participated in the first evaluation in 2012/2013 (T1), and 68% of these were women. In the following year, 2013/2014 (T2), 92% (45 of 48 students) took part; 62% of these were women and 38% men. The 2014/2015 evaluation (T3) comprised 94% (45 of 48 students). Of these, 67% were women.

RESULTS

In the evaluation, the students gave the course a positive grade. The questions in "General/Organization" were given a mean (M) of 1.5 (SD=0.7) in T1 and T2, and 1.2 (SD=0.3) in T3. The "Overall Assessment" yielded M(T1)=1.6 (SD=0.6), M(T2)=1.5 (SD=0.5) and M(T3)=1.1 (SD=0.3). In T1 and T2, the item "The instructor actively involved the students in the course" was given a mean of 2.1 (SD=0.9), and in T3 a mean of 1.2 (SD=0.5).

CONCLUSIONS

The course presented here conceptually shows how practical dental skills can be taught in a theoretical and clinical context. Educational objectives from the role of a dental expert were taken from the national competence-based catalog of educational objectives for dentistry and can also be supplemented. The objectives can be transferred to other dental faculties.

Learning Shade Differentiation Using Toothguide Trainer and Toothguide Training Box: A Longitudinal Study with Dental Students

The positive training effect achieved with the Toothguide Training Box (TTB) has been demonstrated in previous studies. The aim of this study was to investigate the training effect with the TTB at six and 12 months using standardized color tests. The study involved 101 dental students. The participants were divided into two study groups and one control group. Ten standard color samples were determined under uniform environmental conditions with VITA 3D-Master. The control group (N=30) took the color test after one week. Study group 1 (N=49) took the color test after six months and study group 2 (N=22) at 12 months for the first time by following the TTB curriculum. The control group achieved an average ΔEt1=0.85. In study group 1, the ΔEt2 was 2.29, and in study group 2, ΔEt3=2.25. The results after six and 12 months were highly significant compared to the control group (α=0.001). Dependence was determined only with regard to gender. In this study, the TTB quickly led to an improvement in tooth color differentiation among students. After six months, there was a decrease in the training effect. These results suggest that the TTB curriculum should be provided at the end of preclinical training.