Amelogenesis Imperfecta: Case Study

Amelogenesis imperfecta (AI) refers to a group of rare genetic disorders that involve tooth development and that are passed down through families as a dominant trait. This condition is characterized by abnormal enamel formation caused by gene mutations that alter the quality and/or quantity of enamel. This dental problem can impact both primary and permanent dentition, varies among affected individuals, and results in esthetic and functional problems. This condition caused the patient in the current case report to have a lack of confidence when speaking. The treatment for amelogenesis imperfecta depends on the severity of the problem and age of the patient. It is crucial to plan a proper remedy, which requires collaboration among dental specialties to execute comprehensive dental treatment in order to provide a long-term solution with adequate esthetics. The current clinical study presents a patient affected by AI that was diagnosed when the patient was a child. The interdisciplinary treatment continued throughout his childhood and into adult life. The initial treatment consisted of resin composite veneers and stainless-steel crowns to restore the defective tooth structure. The malocclusion of the patient was corrected using a fixed orthodontic appliance that was placed when he had an entire permanent dentition. The treatment plan was eventually intended to include all ceramic crowns and veneers.

[Effect of repeated sintering and variations in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers]

Objective The aim of this study is to evaluate the effect of repeated sintering and variation in thickness on the color and microstructure of dental lithium disilicate-based glass ceramic veneers. Methods A total of 24 computer aided design and computer aided manufacturing (CAD/CAM) veneers was fabricated using the IPS e.max-CAD LS2 and then randomly divided into four groups (S0, S1, S2, S3; n=6). Each group was sintered 0, 1, 2, 3 times individually according to the manufacturer's recommendation. The color parameters (L, C, H, a, b values) of all the specimens were measured by a Vita easyshade dental colorimeter. The results were statistically analyzed using the SAS 9.1.3 software for MANOVA and LSD. Subsequently, the microstructures of the intersecting surfaces of the specimens were observed by scanning electron microscopy (SEM). Results After repeated sintering, the L value significantly decreased (P<0.05). For the C and b values, statistical differences were observed among the groups except between S2 and S3. SEM results showed that the interlocking microstructures of rod-shaped Li₂Si₂O₅ crystals became more compact when the number of sintering times was increased. Conclusion Repeated sintering exhibited significant influence on the color of the IPS e.max-CAD LS2 veneers.

Ceramic Veneers With Gingiva-Shaded Porcelain to Replace Lost Interdental Papillae: A Case Report

With implant-supported reconstructions, gingiva-shaded pink-colored restorative materials serve as an option for replacing both hard and soft tissues cosmetically. This article presents a case report describing restorative treatment for a patient who requested individual crowns and veneers after she had had multiple surgical interventions to replace a failing implant tooth No. 9. In addition to replacement of the implant prosthesis, this case involved restorative papillae reconstruction that was performed to treat interdental recession that had occurred after the surgeries. A beveled slip-joint concept was used whereby the flat plane approximating porcelain surfaces would not be visible from the frontal perspective, resulting in an esthetic-appearing restoration.

Optical Properties and Failure Load of Thin CAD/CAM Ceramic Veneers

This study aimed to compare optical properties and failure load of leucite (IPS Empress CAD LT) and lithium disilicate glass ceramic (IPS e.max CAD LT) materials in incisor veneers. Four groups of veneers were made on 36 bovine incisors with Cerec 3D milling unit (n=9/group): 0.5 and 0.3 mm thick leucite glass and 0.5 and 0.3 mm lithium disilicate glass veneers. The optical features were measured with CM-700d spectrophotometer using white and yellow try-in pastes. Differences were determined by means of ΔE value and luminance. The bovine teeth with veneers were mounted on acrylic resin blocks (Palapress, Heraeus Kulzer) and static loading test was conducted (LR30K plus, Lloyd Instruments). The color difference of veneers could be noticed with yellow and white cements when the material thickness increased from 0.3 to 0.5 mm (leucite ΔE yellow 4.4, white 6.0; lithiumdisilicate ΔE yellow 2.1, white 4.1). Both materials showed similar failure load with 0.5 mm veneers (leucite 1906 +/-319 N; lithiumdisilicate 2098 +/- 309 N). The failure load of 0.3 mm thick lithium dilisilicate veneers (2002 +/- 427 N) was comparable with the 0.5mm veneers. Ultrathin lithium disilicate glass ceramic veneers (0.3 mm) could be a potential option for clinical use.

Three generations of zirconia: From veneered to monolithic. Part II

This article presents the historical development of the different generations of zirconia and their range of indications, from veneered to monolithic zirconia restorations. While Part I concentrated on detailed information about the development of zirconia for dental use and the mechanical and optical properties, Part II deals with the resulting guidelines for working with the relevant generations by summarizing the correct cementation procedure. Furthermore, this part also focuses on translucency measurements for better characterization and understanding of the different materials. The results obtained from measuring light transmission and contrast ratio are compared and discussed in detail, with the aid of clinical photographs. Finally, the reader is given practice-relevant recommendations for different areas of clinical use of the zirconia generations along with advice on how to process them appropriately.

Does Post-etching Cleaning Influence Bond Strength of Lithium Disilicate Laminate Veneers?

This paper aims to present a clinical case of laminate veneers in lithium disilicate (LD) reinforced ceramic, complemented with scanning electron microscopy and energy dispersive x-ray spectroscopy analysis of this ceramic's surfaces submitted to some of the different post-etching cleaning protocols proposed by literature. Many dentists are applying all-ceramic restorations, especially veneers, with the most applied material being LD, due to its good mechanical properties, esthetics, and ability to adhere to tooth substrate. The cementation process is critical to clinical success of indirect restorations. Combination of hydrofluoric acid and silane application on the inner surface of ceramic has been the most recommended method to increase bond strength between ceramic and tooth substrate. As a result of surface corrosion, residual subproducts are formed and precipitate on the ceramic surface, affecting the bonding process to the resin cement. Elimination of residue is recommended in the literature and can be done via 3 common techniques: thorough washing with air/water spray for 30 seconds, 37% phosphoric acid for 60 seconds, or ultrasonic bath for 4 to 10 minutes. Little information on LD ceramics post-etching cleaning methods is available in the literature. For this ceramic, the thorough washing with air/water spray for 30 seconds appeared to remove most of the residue without damaging the material. Being also the most practical and easiest of the reviewed procedures, it was, therefore, the protocol of choice for the clinical cases presented in this paper with success after 18 months.

Conservative, Functional, and Esthetic Rehabilitation of Severe Palatal Erosion (Class IV) Using Modified Dahl Approach

This article demonstrates the clinical application of biomechanical and occlusal principles to conservatively provide optimal clinical outcomes in restoring an eroded anterior dentition. The authors manage a challenging case involving limited palatal clearance (ie, deep bite) coupled with palatal erosion and wear by combining the centric relation (CR) and Dahl principles to create anterior interocclusal space to reduce the need for more invasive palatal reduction. The combined use of adhesive restorations-resin composites on the palatal surface and indirect porcelain veneers on the facial/incisal surfaces-through enamel and dentin bonding helped optimize esthetic and functional/biomechanical aspects. This ultraconservative approach enabled the desired esthetic and biomechanical outcomes to be achieved through the treatment of localized anterior tooth erosion and wear. In short, when treating eroded maxillary anterior teeth with deep bite, adequate restorative space should first be created by conjoining CR and Dahl principles before using adhesive dentistry to restore with bonded composites and porcelain veneers.

Characterization of a Diamond Ground Y-TZP and Reversion of the Tetragonal to Monoclinic Transformation

PURPOSE

To characterize the surface of an yttria-stabilized zirconia (Y-TZP) ceramic after diamond grinding in terms of its crystalline phase, morphology, mean roughness (Ra), and wettability as well as to determine a thermal treatment to reverse the resulting tetragonal to monoclinic (t-m) transformation.

METHODS AND MATERIALS

Y-TZP specimens were distributed into different groups according to the actions (or no action) of grinding and irrigation. Grinding was accomplished using a diamond stone at a low speed. The samples were characterized by x-ray diffraction (XRD), scanning electron microscopy, goniometry, and profilometry. In situ high-temperature XRD was used to determine an annealing temperature to reverse the t-m transformation. Ra was submitted to the Kruskal-Wallis test, followed by the Dunn test (α=0.05). The volume fraction of the monoclinic phase and contact angle were submitted to one-way analysis of variance, followed by the Tukey test (α=0.05).

RESULTS

Monoclinic zirconia was observed on the surface of samples after dry and wet grinding with a diamond stone. The volume fraction of the monoclinic phase was smaller on the dry ground samples (3.6%±0.3%) than on the wet ground samples (5.6%±0.3%). High-temperature XRD showed reversion of the t-m phase transformation, which started at 700°C and completed at 800°C in a conventional oven.

CONCLUSIONS

Grinding with a diamond stone partially transformed the crystalline phase on the surface of a Y-TZP ceramic from tetragonal to monoclinic zirconia while simultaneously increasing the surface roughness and wettability. The t-m transformation could be reversed by heat treatment at 800°C or 900°C for 60 minutes or 1000°C for 30 minutes.

Concept of Minimally Invasive Indirect Veneers

Minimally invasive indirect veneers (MIIV) are ultrathin porcelain veneers that can be cemented onto labial surfaces after no or minimal tooth preparation. The benefits of no or minimal veneer preparation are conservation of tooth structure, absence of postoperative sensitivity, bonding to enamel, minimal flexural stresses, no need for provisionals and improved patient acceptance. However, no or minimal preparation veneers should be considered only after thorough functional and aesthetic evaluation. The article presented here illustrates a case of diastema closure using MIIV, to highlight the importance of treatment planning for achieving good results.

Effect of newly Developed Resin Cements and Thermocycling on the Strength of Porcelain Laminate Veneers

AIM

The aim of this study was to determine the effect of different luting cements and accelerated artificial aging (AAA) in the fracture resistance of porcelain laminate veneers (PLVs).

MATERIALS AND METHODS

A total of 80 disc-shaped specimens were prepared using computer-aided design/computer-aided milling technology from lithium disilicate glass-ceramic blocks. Specimens (0.5 mm thick, 10 mm diameter) were divided into eight groups of 10 specimens per group. The control groups consisted of specimens without cement and not subjected to AAA (CN group) and specimens prepared without cement but subjected to AAA (CW group). The experimental groups were subjected to AAA and cemented with Variolink Veneer, Variolink Esthetic LC, Variolink Esthetic DC, RelyX Unicem, RelyX Veneer, or RelyX Ultimate. Specimens were individually tested for biaxial flexure on a universal testing machine. One-way analysis of variance and the Tukey's post hoc test were used to compare the groups' significance statistically (α = 0.05).

RESULTS

The loads to fracture (LTF) values in the CN group were higher than those in the CW and experimental groups. The lowest LTF value was in the CW group (31.5 ± 9.5 N) and the highest LTF value in the CN group (56.7 ± 10.6 N). Tukey's post hoc test demonstrated a statistically significant (p < 0.01) difference between the CN group and the other groups.

CONCLUSION

Artificial aging had a significant effect on the LTF value of the tested specimens compared with the resin cements used. Cohesive failure within the PLVs was the most common mode of failure.

CLINICAL SIGNIFICANCE

Fatigue strength of dental ceramics and moisture was shown to affect the mechanical properties of all-ceramic restorations. All-ceramic material is extremely sensitive to humidity and thermocycling.

[Effect of ceramic thickness and resin cement shades on final color of heat-pressed ceramic veneers]

Objective: To analyze the effect of ceramic materials thickness and resin cement shades on the final color of ceramic veneers in the discolored teeth, and to investigate the color agreement of try-in pastes to the corresponding resin cements. Methods: Sixty artificial maxillary central incisor teeth (C2 shade) were used to simulate the natural discolored teeth and prepared according to veneer tooth preparation protocol. Veneers of different thickness in the body region (0.50 and 0.75 mm) were fabricated using ceramic materials (LT A2 shade, IPS e.max Press). The ceramic veneer specimens were bonded to the artificial teeth using the 6 shades of resin cements (Variolink Veneer: shades of LV-3, LV-2, HV+3; RelyX™ Veneer: shades of TR, A3, WO) (n=5). A clinical spectrophotometer was used to measure the color parameters of ceramic veneers at the cervical, body and incisal regions. Color changes of veneers before and after cementation were calculated and registered as ΔE1, and the changes between try-in paste and the corresponding resin cements were registered as ΔE2. Results: Three-way ANOVA indicated that ΔE1 and ΔE2 values were significantly affected by the ceramic thickness, resin cement shades and measuring regions (P<0.05). The ΔE1 values of six shades ranged from 0.59-8.27. The ΔE1 values were more than 2.72 when the ceramic veneers were cemented with resin cements in shades of HV+3 and WO. The ΔE2 values of six shades ranged from 0.60-2.56. The shades of HV+3, WO and A3 resin cements were more than 1.60. Conclusions: Different thickness of ceramic materials, resin cement shades and measuring regions could affect the final color of ceramic veneers. The color differences of some resin cements and corresponding try-in pastes might be observed in clinical practice.

Minimally Invasive All-ceramic Preparation for the Occlusal Face: The "V Preparation"

A clinical case illustrates and explains step by step a minimally invasive molar occlusal surface preparation for all-ceramic bonded restoration. The sequential use of calibrated burs, following the specific procedure, systematically and quickly, provides a perfectly calibrated reduction of the occlusal face even for an inexperienced practitioner. This preparation increases the bonding surface and optimizes the accommodation of constraints that provides a more resistant reconstruction and favors the preservation of the vital tooth. This procedure, called a "V preparation" or V prep, is discussed in the case report below.

[Evaluation of the effect of modified wet particle erosion on bond strength between 3Y-TZP zirconia framework and veneering porcelain]

PURPOSE

To evaluate the effect of bond strength between 3mol% yttrium-stabilized tetragonal zirconium polycrystal (3Y-TZP) zirconia framework after modified wet particle erosion and veneering porcelain.

METHODS

A total of 174 [8 mm× 8 mm× 3 mm (±0.02)] specimens were prepared and then randomly divided into different groups according to different particle size, sandblasting pressure, sandblasting time through conventional sandblasting (experimental groups); specimens in the control group were not sandblasted. The bond strength between 3Y-TZP zirconia framework and veneering porcelain was measured using a universal testing machine. Statistical analysis was performed using SPSS17.0 software package. The bond strength of specimens treated by two methods-conventional sandblasting and modified wet particle erosion under the same condition (150 μm, 0.6 MPa, 30 s) were acquired, while the surface was analyzed microscopically before the specimens were veneered with the veneering ceramic under scanning electronic microscope (SEM).

RESULTS

The bond strength of conventional sandblasting group under the condition (110 μm, 0.4 MPa,30 s) was maximal, and significantly higher than the control group (P<0.05). The bond strength of modified wet particle erosion group was significantly higher than the conventional sandblasting group and control group (P<0.01); SEM showed that the surface of specimen with modified wet particle erosion was homogeneously rough; the surface specimen with conventional sandblasting was heterogeneously rough, some microcracks were seen in some areas.

CONCLUSIONS

Sandblasting can slightly enhance the bond strength between 3Y-TZP zirconia framework and veneering porcelain, modified wet particle erosion is recommended for 3Y-TZP zirconia framework surface treatment.

Effect of contact stress on the cycle-dependent wear behavior of ceramic restoration

AIM

Ceramic restoration experiences the non-linear wear process during the chewing simulation, which contains running-in, steady and severe wear stages. However since various levels of contact stress may be applied on the occlusal surface during chewing, the cycle-dependent wear behaviors of ceramic crowns may differ. The aim of this study was to investigate the effect of contact stress on the development of wear behavior, as tested in a chewing simulator.

MATERIALS AND METHODS

Thirty-six anatomical metal-ceramic crowns using Ceramco III as the veneering porcelain were randomly assigned to two groups based on the contact stress applied in the wear testing. Stainless steel balls served as antagonists. The specimens were dynamically loaded in a chewing simulator up to 2.4×10⁶ loading cycles, with additional thermal cycling between 5 and 55℃. For each group, several checkpoints were employed to measure the substance loss of the crowns' occlusal surfaces and to evaluate the microstructure of the worn areas.

RESULTS

After 2.4×10⁶ cycles, the ceramic restorations with lower contact stress demonstrated a long steady wear stage following the running-in, but without the severe wear stage. And a slowly microstructural degradation was observed that the subsurface defect could not be seen until final. With higher contact stress, however, the ceramic restorations experienced a faster transition from running-in to severe wear stage that the steady wear stage nearly disappeared. And an early formation of subsurface defects and the deterioration of microstructure were observed.

CONCLUSIONS

Contact stress is a key factor affecting the wear development of ceramic restoration. The higher contact stress promotes the veneering porcelain to evolve into severe wear stage. In contrast, lower contact stress is prone to keep the veneering porcelain operating in steady wear stage, which delays the arrival of severe wear region.

Implant- and Tooth-Supported Fixed Prostheses Using a High-Performance Polymer (Pekkton) Framework

The type of prosthetic restoration used in implant rehabilitation greatly contributes to the recovery of masticatory function as well as quality of life in patients. Frameworks for implant-supported prostheses are typically made by casting metal or milling either titanium or zirconia. Recently, nonmetal, polymer-type materials were suggested as framework materials. Polyetherketoneketone (PEKK), a high-performance polymer, was recently introduced in the dental field with potentially wide-ranging applications. This case history report describes implant- and tooth-supported fixed prostheses created using a new high performance polymer (Pekkton, Cendres+Metaux) framework for a fully edentulous maxilla and partially edentulous mandible.

Marginal sealing of a porcelain laminate veneer luted with three different resin cements on fluorosed teeth

AIM

The purpose of this study was to investigate the sealing ability of three different resin cements for the luting of a porcelain laminate veneer (PLV) to the enamel and dentin of fluorosed teeth.

MATERIALS AND METHOD

Thirty incisors with moderate fluorosis according to the Thylstrup-Fejerskov Index (TFI = 4 to 6) received a veneer preparation with dentin margins at the gingival third. The IPS Empress (Ivoclar Vivadent) veneers were luted to the teeth of three groups (n = 10) using three different resin cements: Group 1: Excite DSC/Variolink II - etch-and-rinse (E&R), Group 2: ED Primer II/Clearfil Esthetic - self-etch (SE), Group 3: RelyX Unicem - self-adhesive (SA). After 24 h of water storage and thermocycling, marginal microleakage was evaluated on three slices from each tooth using the dye penetration technique under a digital microscope.

RESULTS

Data (microleakage percentage over the entire preparation length) were analyzed using the Kruskal-Wallis and Mann-Whitney tests (P < 0.05). Mean microleakage percentage was 0.8% to 18% at the enamel and dentin margins, respectively. On the enamel, Group 1 (E&R) exhibited significantly less microleakage compared to Groups 2 (SE; P = 0.03), and 3 (SA; P = 0.005). On the dentin, microleakage in Group 3 (SA) was significantly less than that in Groups 1 (E&R, P = 0.001), and 2 (SE; P = 0.03). The difference between the latter two groups was significant, with Group 1 (E&R) exhibiting the greatest microleakage.

CONCLUSION

The best enamel and dentin sealing of the cemented veneers was obtained with the E&R and SA luting agents, respectively.

Ceramic laminate veneers: clinical procedures with a multidisciplinary approach

Complex cases with high esthetic needs represent a challenge for clinicians. A multidisciplinary approach is vital to achieve the planned result. New technological devices are needed to facilitate the collaboration between the clinical team members and to develop a fluent and effective diagnostic and therapeutic pathway. This article describes a well-defined protocol for the treatment of complex esthetic cases with the use of ceramic laminate veneers. The protocol involves different branches of dentistry: periodontal therapy, mucogingival surgery, restorative dentistry, orthodontics, and prosthodontics. Each step of the protocol should be executed in a very strict order: intra- and extraoral esthetic analysis of the patient, with photographs; digital previsualization by means of Digital Smile Design (DSD); clinical previsualization by means of a mock-up; orthodontic, mucogingival, and endodontic treatments, if needed; minimally invasive tooth preparation, driven by a mock-up and silicone indices; manufacture of ceramic laminate veneers; try-in and adhesive cementation. In this article, this protocol is illustrated by a clinical case report in which all the above-mentioned steps were carried out. The finalization was obtained by means of state-of-the-art adhesive techniques and ceramic laminate veneers. The correct use of modern materials, in combination with rigorous adhesive procedures, allows for a minimally invasive and highly esthetic treatment, with adequate function and a perfect integration that is in harmony with the patient's face.

Porcelain veneer post-bonding crack repair by resin infiltration

Ceramic laminate veneer restorations are indicated in several clinical situations. Indirect restorations are usually chosen if the less-invasive options - bleaching, resin infiltration, or composite resin restorations - are not possible, or when it is too difficult to achieve an esthetically pleasing result in the long term. Bonded indirect partial restorations are highly dependent on their adhesive interface, as these thin restorations have a relatively low cohesive strength. Therefore, preservation of sound enamel, conditioning of the restorations and of the substrate, and luting procedures are of paramount importance for a successful outcome. Even when utmost care is taken during every step of the procedure, failures such as fractures, chipping, or marginal discoloration and defects sometimes occur. Only very few of these cases of failure are presented or are a subject of interest. In this case presentation, a fracture repair is performed using an infiltration technique with a resin composite material.

Ceramic vs composite veneering of full arch implant-supported zirconium frameworks: assessing patient preference and satisfaction. A crossover double-blind randomised controlled trial

PURPOSE

The objectives of this two-period, crossover, mono-centred, double-blind, randomised controlled trial (RCT) were to compare two different materials used for full arch implant-supported prosthetic restorations with regard to patient preference and impact on a patient's quality of life.

MATERIALS AND METHODS

Edentulous patients requesting one full arch restoration in the mandible or maxilla supported by dental implants were included in this study. Patients were randomised to receive either a full arch zirconia framework hand-veneered with ceramic, or a full arch zirconia framework hand-veneered with composite material. After 1 month, the first randomised restoration was substituted by the other, which was left in function for a further observation period of 1 month. Outcome measures were: patient preference and satisfaction (OHIP-21), complications, visual analogue scales for chewing comfort, aesthetic acceptance, phonetic comfort, full mouth plaque score (FMPS).

RESULTS

Twenty-four patients were randomised to the treatments in the two periods. There was one dropout. At the end of the study, 16 patients (70%) preferred to wear ceramic prosthesis and 7 patients (30%) preferred to wear composite prosthesis (ceramic preference: 70%; 95%CI from 47 to 87%; P = 0.0605). Difference in OHIP-21 reduction between the two treatments was not significant (difference 0.5, 95%CI from -2.8 to 3.8, P = 0.7788). There was one minor complication during the ceramic period in one patient and one minor complication during the composite period in another patient (odds ratio 1.00, 95%CI from 0.06 to 15.99, P = 1.0). The difference in FMPS between treatments was not significant (0.5, 95%CI from -1.3 to 2.2, P = 0.5731). Difference in VAS between the two treatments was not significant for general satisfaction (P = 0.2067), chewing comfort (P = 0.8345) and phonetics (P = 0.9167). Difference in VAS between the two treatments was significant for aesthetic acceptance favouring the ceramic prosthesis (difference 0.9, 95%CI from 0.006 to 1.8, P = 0.0486).

CONCLUSIONS

No difference between the two treatments was detected for preference, changes of OHIP-21, complications, reduction of FMPS, VAS changes regarding patient satisfaction, chewing and phonetics. Nevertheless, a slight difference was detected in the VAS regarding aesthetic acceptance favouring the ceramic material.

FUNDING

The study was supported by Nobel Biocare (grant 2012-1077). Thanks to this contribution, the patients who consented to participate in this RCT were not charged for the material provided by Nobel Biocare. In addition, the patients benefited from a further back-up prosthesis that was provided to them completely free of charge.

Effectiveness of optical illusions applied on a single composite resin veneer for the diastema closure of maxillary central incisors

OBJECTIVE

To assess the esthetic effectiveness of four illusion techniques applied to a composite resin veneer for diastema closure between maxillary central incisors.

MATERIALS AND METHODS

An acrylic model with six natural maxillary anterior teeth was fabricated with a 2-mm diastema between the central incisors. Resin veneers were constructed on the left central incisor and the following cases were derived: V0: no veneer; V1: veneer without optical illusion features; V2: veneer with centralized interproximal ridges; V3: veneer with curved incisal edges; V4: veneer with gray pigment mesially/distally; V5: veneer with gray pigment on the developmental lobes. Digital printed photos of the models (13.2 x 17.8 cm, and 6.1 x 8 cm), with low, medium, and high smile lines and without a smile line (processed by Adobe Photoshop CS6) were shown to three groups of people (faculty members, senior undergraduate students, and patients; n = 25/group) for them to assess the overall size and width of the two central incisors. The results were analyzed by Pearson's and chi-square goodness of fit tests.

RESULTS

There was no significant influence in the estimation of the two central incisors as being the same size, according to the technique used (P = 0.869) and group of evaluators (P = 0.209). The estimated probability of assessing the tested incisor as wider was indicatively lower in V2 compared to V1 (adjusted odds ratio = 0.59; P = 0.088). The height of the smile line affected the evaluation of the veneers only in the large-sized photos.

CONCLUSIONS

No interference is the best esthetic decision concerning a 2-mm diastema closure when restoring only one central incisor with a laminate veneer. The next best option is to deliver a veneer with centralized interproximal ridges.

Load bearing capacity, fracture mode, and wear performance of digitally veneered full-ceramic single crowns

OBJECTIVES

Computer-aided technologies can help to minimize clinical complications of zirconia-based restorations such as veneering porcelain fractures. The aim of this study was to evaluate different veneering approaches for zirconia single crowns regarding contact wear, fracture strength, and failure mode.

METHODS

Six different types of computer-aided design (CAD) crowns were manufactured and conventionally cemented on 10 metal dies each: three groups with a zirconia framework and a CAD/CAM-fabricated veneering cap ("digital veneering system": DVS, CAD-on, Infix CAD), zirconia-based crowns with pressed veneering caps (Infix Press), zirconia framework containing the dentin layer with only the incisal enamel material added (dentin-core), and conventional substructure with powder buildup veneering porcelain (layering technique). All specimens were submitted to artificial aging (120,000 mechanical cycles, 50 N load, 0.7-mm sliding movement, 320 thermocycles). After contact wear was measured with a laser scanning system, fracture resistance and failure mode were examined using a universal testing machine and a scanning electron microscope. Statistical analysis was performed at a significance level of 5%.

RESULTS

No statistical difference was revealed regarding the contact wear of the restorations (P = 0.171; ANOVA). No significant difference was found regarding the fracture resistance of the crowns (P = 0.112; ANOVA). Failure analysis revealed three different failure patterns: cohesive veneering fracture, adhesive delamination, and total fracture, with a characteristic distribution between the groups.

SIGNIFICANCE

All tested specimens survived artificial aging and exhibited clinically acceptable wear resistance and fracture resistance. Digital veneering techniques offer a promising, time- and cost-effective manufacturing process for all-ceramic restorations and may usefully complement the digital workflow.

Clinical outcomes of full arch fixed implant-supported zirconia prostheses: A systematic review

AIM

The primary aim of this systematic review was to study the clinical outcomes of one-piece fixed complete dentures (complete arch fixed implant-supported prostheses) made of zirconia for edentulous patients. The secondary aim was to compare the clinical outcomes of monolithic zirconia vs zirconia veneered with porcelain (conventional, minimal or gingival) for fixed complete dentures.

MATERIALS AND METHODS

Two investigators conducted an independent electronic search of the literature, using PubMed and Scopus search engines from January 1, 2000, to August 31, 2016. After application of pre-determined inclusion and exclusion criteria, the final list of articles was reviewed to meet the aims of this review.

RESULTS

A total of 12 observational studies were identified that satisfied the inclusion criteria of this systematic review. Short-term results from a combined 223 patients with 285 one-piece zirconia fixed complete dentures showed a mean failure rate of 1.4% due to the fracture of four prostheses. Prosthetic complications occurred in 46 prostheses (16.1%). Out of these, 42 prostheses (14.7%) had minor complications exclusive to fracture of veneered porcelain.

CONCLUSIONS

Current evidence indicates that zirconia fixed complete dentures have a very low failure rate in the short term, but have a substantial rate of minor complications related to chipping of veneered porcelain. Use of monolithic zirconia with only gingival stains, or zirconia that is veneered only at the gingiva may offer promising results, but will need to be validated by future long-term studies. Conflict-of-interest statement: All authors report no conflict of interest.

Premium protocol for planning a periodontal-restorative approach: Conservative, predictable, and reproducible

Planning oral rehabilitation that involves an interdisciplinary approach is challenging, especially when it includes changes in the morphologic aspects of teeth and the architecture of gingival tissues. Patients commonly complain about the esthetics of maxillary anterior teeth, especially when diastemata are present. A guideline known as the golden proportion can be used to establish adequate width distribution of anterior teeth. Tooth proportion is also affected by incisogingival tooth length, hence gingival contouring should be evaluated as well. In these situations, the width-to-height ratio of 0.75:0.78 in the maxillary anterior teeth could be used to obtain wax-ups and a surgical guide, resulting in a more predictable esthetic outcome. Therefore, this clinical report describes a protocol for the planning of a periodontal-restorative approach with two wax-ups and a surgical guide using the golden proportion width-to-height ratio of 0.75:0.78 for the treatment of maxillary anterior teeth with diastemata using minimum thickness lithium disilicate veneers.

A new veneer technique with prefabricated composite denture teeth combined with the "Biologically Oriented Preparation Technique" (BOPT) - a case report

This clinical report describes the step-by-step protocol for novel, 100% non-prep, custom-modified, prefabricated composite veneer restorations in the case of an esthetic rehabilitation of a patient presenting peg-shaped lateral incisors and undersized maxillary central incisors. A correct diagnosis, comprehensive treatment plan, and an interdisciplinary approach are necessary to obtain optimal conservative and predictable esthetic results.

Vertical dimension augmentation with a full digital approach: a multiple chairside sessions case report

The last few decades have seen an upward trend of the pathologies of abrasion, erosion, and abfraction. These pathologies, especially in combination, can provoke a significant loss of tooth substance. Nowadays, modern digital chairside technologies and new restorative materials allow clinicians to restore the lost tooth structure with a minimally invasive and fully digital approach. This article describes a step-by-step procedure of a full-mouth rehabilitation performed with a total digital chairside approach in several appointments.

From orthodontic treatment plan to ultrathin no-prep CAD/CAM temporary veneers

Several treatment options are described in the literature to solve the microdontia-related problems of maxillary anterior teeth. These options are often focused on an orthodontic rather than a restorative approach. The case presented here started with an orthodontic phase followed by a restorative one. The aim of the orthodontic phase was to achieve the correct spacing, respecting ideal average tooth proportions. This was done using a digital setup to restore the six anterior teeth, so that an optimal esthetic and functional result was achieved by the end of the orthodontic treatment. The purpose of the restorative phase was to contribute to the esthetic outcome and occlusal stability. The 12-year-old patient was treated utilizing a CAD/CAM procedure, which took advantage of the mechanical properties and reasonable cost of the chosen resin matrix ceramic material (Vita Enamic). Once stability has been attained and proper periodontal tissue maturation has been reached at the end of the patient's growth, there will then be the option of improving the esthetics by replacing these restorations with ceramic veneers.

Full-Mouth Implant Rehabilitation With Monolithic Zirconia: Benefits and Limitations

As increased chipping rates have been reported with porcelain-fused-to-zirconia fixed dental prostheses, monolithic zirconia has been introduced in an effort to reduce the technical complications associated with bilayered ceramics. This clinical report illustrates the steps for achieving full-mouth implant rehabilitation with monolithic zirconia prostheses and minimal facial porcelain veneering. The benefits and limitations of this technique are also discussed. The incisal edges and occluding surface areas comprised monolithic zirconia to reduce the possibility of breakage and improve the esthetic outcome. Up to 1 year in function, no porcelain fracture was found.

Noninvasive bilaminar CAD/CAM composite resin veneers: a semi-(in)direct approach

Direct composite resin restorations have been recognized for their valuable clinical service and respect of intact hard tissue. The cost-effectiveness and inherent minimally invasive approach of resin-based materials means that they are also gaining popularity for use in computer-aided design/computer-aided manufacture (CAD/CAM) procedures. Several cases from the student clinics at the Herman Ostrow School of Dentistry of USC are presented that could have been resolved either with direct composite resin restorations or with indirect porcelain veneers. A novel semi-indirect CAD/CAM approach, characterized by its absolute noninvasiveness and simplicity, was chosen instead. The bilaminar restoration consists of a customized histoanatomical CAD/CAM dentin base (incisoproximal cutback), and a generic enamel skin. The patients can be treated either in one clinical session (semi-directly) or in two clinical sessions (semi-indirectly). The purpose of this article is to present another tool from the anterior restorative armamentarium to bridge the gap between direct and indirect techniques.

[Preliminary clinical evaluation of the esthetic effect of deep discolored anterior teeth restored with zirconia veneers]

OBJECTIVE

To observe the esthetic effect of deep discolored anterior teeth restored by zirconia veneers.

METHODS

Small defected deep discolored anterior teeth with complete root canal therapy were restored by zirconia veneers (n=15). The same name teeth on the other side of the same dental arch were chosen as control teeth. The color difference values ΔE of the neck 1/3, the middle 1/3 and the incisor 1/3 between the deep discolored tooth and the normal control tooth before and after therapy were measured to evaluate the esthetic effect of zirconia veneer restoration. At the same time, the marginal fit of zirconia veneers was checked by the standard of United States Public Health Service (USPHS). The integrity of the veneers was also examined.

RESULTS

On the labial side, fibers color difference values ΔE of the neck 1/3, the middle 1/3 and the incisor 1/3 between deep discolored teeth and normal control teeth were measured by the electronic colorimeter, which were 24.92±3.00,26.64±4.00 and 21.94±3.31 respectively. All the values were above 4.0, which were considered unacceptable in clinic. After restoration by zirconia veneers, the color difference values ΔE of the middle 1/3 and the incisor 1/3 between the restored and control teeth were 1.82±0.17 and 1.84±0.21. Both values were less than 2.0, which indicated both good color matching. The color difference value ΔE of the neck 1/3 was 3.92±0.48, which was less than 4.0 and could be accepted in clinic. The statistical analysis of the colors of the teeth before and after restoration compared with the control teeth was done by Paired t test. The t values in the neck 1/3, the middle 1/3 and the incisor 1/3 were 30.37, 21.56, 23.37 respectively. In the three group, all the P<0.001. There were obvious statistical differences. According to the standard of USPHS, the marginal fit of all the restored teeth was perfect (grade A). No zirconia veneers were broken or detached in the period of observation.

CONCLUSION

Zirconia veneers can be a good method to restore deep discolored anterior teeth. However, it should be used cautiously when the patient's esthetic expectation was too high.

Effect of Surface Roughness on Flexural Strength of Veneer Ceramics

The strength of ceramic restorations depends on the occlusal surface roughness of the veneering porcelain, which is influenced by the final preparation. The hypothesis of the study was that roughnesses below a critical microscopic defect size—based only on fracture mechanics considerations—also affect flexural strength. The bending failure stress was evaluated on standard specimens of 4 veneer ceramics with 4 different surfaces of defined roughnesses, respectively. A linear correlation was found between roughness and failure stress. A "roughness-free" failure stress value was predicted for each tested material. This theoretical value can represent the "true" strength of the respective ceramic material. We conclude from our results that the final preparation of a ceramic restoration is critical to the strength of the material, and that ceramic veneering materials can be compared more objectively with respect to their strength by means of roughness-free strength values.

Joining Veneers to Ceramic Cores and Dentition with Adhesive Interlayers

Adhesive joining of veneers to cores offers potential simplicity and economy in the fabrication of all-ceramic crowns. We tested the hypothesis that resin-based adhesives can be used for such fabrication without compromising mechanical integrity of the crown structure. A simple test procedure for quantifying this hypothesis was proposed. A model glass veneer layer 1 mm thick (representative of porcelain), adhesively bonded onto a glass-like core substrate (ceramic or dental enamel), was loaded at its top surface with a hard sphere (occlusal force) until a radial crack initiated at the veneer undersurface. The critical loads for fracture, visually observable in the transparent glass, afforded a measure of the predisposition for the adhesive to cause veneer failure in an occlusal overload. Two adhesives were tested, one a commercial epoxy resin and the other a relatively stiff in-house-developed composite. The results confirmed that stiffer adhesives provide higher resistance to failure.

[Color selection of ultrathin veneers in clinic]

Ultrathin veneer is a new therapeutic technology developed from minimally invasive theories. Ultrathin veneer alters the unwanted shape and color of a tooth through minimal or lack of preparation. The color of tooth after restoration is mixed with the natural color of tooth, the original color of veneer, and the color of bonding material because of ultrathin (approximately 0.2 mm) veneer. Thus, the color is affected by numerous variations. Full considerations are required for creating designs. The author summarizes clinical points and provides suggestions for ultrathin veneer in color.

Does the Material Stiffness of Novel High-Performance Polymers for Fixed Partial Dentures Influence Their Biomechanical Behavior?

PURPOSE

To investigate the influence of framework materials with different elasticity moduli on the biomechanical performance of fixed partial dentures (FPDs).

MATERIALS AND METHODS

A tooth-anchored three-unit FPD and surrounding tissues were modeled in two variants (veneered/full anatomical FPD) and loaded on the central unit. Three different framework materials (titanium, zirconia, high-performance polymer) were simulated.

RESULTS

The polymer framework resulted in reduced framework stresses and increased veneering stresses. Varying the framework material had minimal influence on the loading of surrounding tissue.

CONCLUSIONS

Using soft, novel materials as framework for dental FPDs does not negatively influence biomechanical loading of the involved biologic structures.

Fracture Strength, Failure Types, and Weibull Characteristics of Three-Unit Zirconia Fixed Dental Prostheses After Cyclic Loading: Effects of Veneering and Air-Abrasion Protocols

The required connector dimension for zirconia fixed dental prostheses (FDPs) may be a clinical limitation due to limited space in the occlusogingival direction. Using no veneering in the gingival regions of the pontics and connectors may solve this problem. This study evaluated the mechanical durability of zirconia FDPs with and without veneering in the gingival area of the connectors and pontics and subsequent air abrasion of this region with different protocols. Models were made of resin abutments (diameter = 6 or 8 mm, height = 6 mm, 6 degrees convergence) and embedded in polyurethane resin (distance = 11 mm). Zirconia frameworks were milled and randomly distributed by veneering (veneering of the entire framework [VEN] or no veneering at gingival regions of the pontic and connector [NVEN]) and by air-abrasion (Al₂O₃/SiO₂, 30 μm; or 45 μm Al₂O₃. FDPs were adhesively cemented and subjected to mechanical cycling (1,200,000 cycles, 200 N, 4 Hz, with water cooling). Specimens were tested until fracture (1 mm/min), and failure modes were classified. Data (N) were subjected to one-way analysis of variance in two sets, Tukey test (α = .05) and Weibull analysis. While veneering did not significantly affect the results (VEN: 1,958 ± 299 N; NVEN: 1,788 ± 152 N; P = .094), air abrasion did (P = .006), with the worst results for the groups conditioned with 45 μm Al₂O₃ (SiO₂: 1,748 ± 273 N; Al₂O₃: 1,512 ± 174 N). The NVEN group demonstrated the highest Weibull modulus (12.8) compared with the other groups (5.3-7.2). Fractures commonly initiated from the gingival side of the connector. Veneering of the gingival region of the connectors and pontics in zirconia FDPs did not diminish the fracture strength, but air-abrasion of this area with 45 μm Al₂O₃ decreased the results.

The influence of tooth color on preparation design for laminate veneers from a minimally invasive perspective: case report

Various types of dental preparations for laminate veneers have been proposed,depending on factors such as the properties of the ceramic material, remaining dental structure color, need for altering the dental contour, laboratory fabrication technique, and occlusal relationships. Clinical observations of successes and failures associated with the development of techniques and materials have allowed some safe parameters to be delineated for effectively performing dental preparations for ceramic veneers or even placing veneers without any preparation. This article describes the use of an additive diagnostic wax-up that is transferred to the mouth by means of an intraoral mock-up (aesthetic pre-evaluative temporary) with associated mathematic parameters to guide dental preparations. This technique, called Do the Math and presented here in the form of a clinical case report, aims to avoid excessive or incorrect tooth preparation by indicating the exact amount and location of the tooth reduction necessary to attain the desired color and shape.

Effect of endodontic access cavity preparation on monolithic and ceramic veneered zirconia restorations

OBJECTIVES

Due to the high chipping rates observed in veneered zirconia ceramic restorations, the use of monolithic zirconia restorations has been recommended. This study tried to compare veneered and monolithic zirconia fixed dental prostheses (FDPs) with respect to the amount of damage induced by endodontic access preparation.

METHOD AND MATERIALS

Monolithic and ceramic veneered (n = 10) three-unit restorations (retainers: first premolar and first molar; pontic: second premolar) were subject to endodontic access cavity preparation in both retainers using a diamond rotary instrument under continuous water cooling. The number of chipping fractures and microfractures detected using the fluorescent penetrant method were recorded. Statistical analysis was based on Wilcoxon rank sum tests with Bonferroni correction (level of significance α = .05).

RESULTS

Only one microfracture could be identified in the group of monolithic FDPs while a maximum of seven microfractures and three chipping fractures per retainer crown were recorded in the group of veneered restorations. At the premolar site, the veneered restorations showed significantly more microfractures (P = .0055) and chipping fractures (P = .0008). At the molar site, no significant difference with respect to microfractures could be detected (P = .0767), while significantly more chipping fractures occurred in the veneered samples (P = .0293).

CONCLUSION

Monolithic zirconia restorations seem to be less susceptible to damage when endodontic access cavities have to be prepared as compared to veneered zirconia reconstructions. However, no conclusions can be drawn on the long-term performance of a specific restoration based on this study.

Impact of Bruxism on Ceramic Defects in Implant-Borne Fixed Dental Prostheses: A Retrospective Study

PURPOSE

Ceramic veneer fracture is a frequent complication in implant-borne fixed restorations. The retrospective clinical study assesses the effect of bruxism on this complication.

MATERIALS AND METHODS

A sample of 507 implant-borne fixed units inserted between 1995 and 2011 in 144 patients were examined. Any detected veneer fractures were assigned to one of four groups according to extent and position. A hypothetical correlation between bruxism and ceramic veneer fractures was examined.

RESULTS

Of 34 patients (23.6%) with at least one ceramic veneer fracture, 24 were bruxers (70%) and 10 were nonbruxers (30%) (P = .002).

CONCLUSION

Bruxism may pose a risk for ceramic fractures.

Sol-gel dip coating of yttria-stabilized tetragonal zirconia dental ceramic by aluminosilicate nanocomposite as a novel technique to improve the bonding of veneering porcelain

The aim of this in vitro study was to evaluate the effect of silica and aluminosilicate nanocomposite coating of zirconia-based dental ceramic by a sol-gel dip-coating technique on the bond strength of veneering porcelain to the yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in vitro. Thirty Y-TZP blocks (10 mm ×10 mm ×3 mm) were prepared and were assigned to four experimental groups (n=10/group): C, without any further surface treatment as the control group; S, sandblasted using 110 μm alumina powder; Si, silica sol dip coating + calcination; and Si/Al, aluminosilicate sol dip coating + calcination. After preparing Y-TZP samples, a 3 mm thick layer of the recommended porcelain was fired on the coated Y-TZP surface. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray analysis were used to characterize the coating and the nature of the bonding between the coating and zirconia. To examine the zirconia-porcelain bond strength, a microtensile bond strength (μTBS) approach was chosen. FT-IR study showed the formation of silica and aluminosilicate materials. XRD pattern showed the formation of new phases consisting of Si, Al, and Zr in coated samples. SEM showed the formation of a uniform coating on Y-TZP samples. Maximum μTBS values were obtained in aluminosilicate samples, which were significantly increased compared to control and sandblasted groups (P=0.013 and P<0.001, respectively). This study showed that aluminosilicate sol-gel dip coating can be considered as a convenient, less expensive reliable method for improving the bond strength between dental Y-TZP ceramics and veneering porcelain.

Influence of Light Irradiation Through Zirconia on the Degree of Conversion of Composite Cements

PURPOSE

To assess the light irradiance (LI) delivered by two light-curing units and to measure the degree of conversion (DC) of three composite cements and one flowable composite when cured through zirconia or ceramic-veneered zirconia plates with different thicknesses.

MATERIALS AND METHODS

Three dual-curing composite cements (Clearfil Esthetic Cement, Panavia F2.0, G-CEM LinkAce) and one light-curing flowable composite (G-aenial Universal Flo) were investigated. Nine different kinds of zirconia plates were prepared from three zirconia grades (YSZ: Aadva and KATANA; Ce-TZP/Al2O3: NANOZR) in three different thicknesses (0.5- and 1.5-mm-thick zirconia, and 0.5-mm-thick zirconia veneered with a 1.0-mm-thick veneering ceramic). Portions of the mixed composite cements and the flowable composite were placed on a light spectrometer to measure LI while being light cured through the zirconia plates for 40 s using two light-curing units (n = 5). After light curing, micro-Raman spectra of the composite films were acquired to determine DC at 5 and 10 min, 1 and 24 h, and at 1 week.

RESULTS

The zirconia grade and the thickness of the zirconia/veneered zirconia plates significantly decreased LI. Increased LI did not increase DC. Only the Ce-TZP/Al2O3 (NANOZR) zirconia was too opaque to allow sufficient light transmission and resulted in significantly lower DC.

CONCLUSION

Although zirconia-based restorations attenuate the LI of light-curing units, the composite cements and the flowable composite could be light cured through the YSZ zirconia. LI is too low through Ce-TZP/Al2O3 zirconia, necessitating the use of self-/dual-curing composite cements.

A 10-Year Clinical Evaluation of Resin-Bonded Fixed Dental Prostheses on Non-Prepared Teeth

This study evaluated the conditions of the non-invasive resin-bonded fixed dental prostheses (FDP) and patient satisfaction up to 10 years of clinical function. A total of 23 patients who required fixed prostheses in the areas of mandibular anterior and premolar, and maxillary anterior region received resin-bonded restorations between 1999-2003. In 13 patients with 14 edentulous areas were restored with an adhesive pontic (natural tooth, acrylic and porcelain). Two indirect proximal veneers using resin composite were placed in each space in 10 patients having 13 edentulous spaces. All prostheses were bonded to the proximal surface of adjacent teeth using resin cement based on 4-META/MMA-TBB. No debonding of proximal veneers but 4 pontic debonding was observed which were rebonded and remained functional until final follow up. The abutments in pontic and proximal veneer groups were free of caries and hypersensitivity. Periodontal health was improved after treatment and was maintained for 10 years except for 4 abutments that still showed some bleeding on probing. Non-invasive resin-bonded FDPs are simple, pain-free, less costly treatment procedures that could provide acceptable clinical longevity with high patient satisfaction.

Try-in Pastes Versus Resin Cements: A Color Comparison

This study aimed to compare the color of ceramic veneer restorations using different shades of try-in pastes and resin cement. Researchers found no differences between try-in pastes and resin cements after cementation.

Combination esthetic treatment of anterior teeth affected by idiopathic enamel hypoplasia: a case report

The esthetic management of enamel dysplasia presents an opportunity for the practitioner to integrate expertise in diagnosis, biomaterials, and technique. In addition to considerations of appearance, careful attention must be paid to occlusal function and restorative material properties. This case report highlights a combined approach of conservative lithium disilicate indirect restorations and composite resin direct veneers to electively restore the anterior teeth of a patient diagnosed with idiopathic enamel hypoplasia.

Ten-Year Follow-Up of Implant-Supported All-Ceramic Fixed Dental Prostheses: A Randomized, Prospective Clinical Trial

PURPOSE

The aim of this study was to evaluate the long-term clinical performance of and patient satisfaction with implant-supported all-ceramic fixed dental prostheses (FDPs) and to compare two different all-ceramic systems, Denzir (DZ) and In-Ceram Zirconia (InZ).

MATERIALS AND METHODS

A total of 18 patients received 25 partial FDPs; 13 DZ, and 12 InZ.

RESULTS

Of these patients, 17 attended the 10-year follow-up. None of the restorations had fractured. Fractures of the veneering porcelain were observed in nine patients; two from the InZ group and seven from the DZ group. All FDPs were in use, and all patients were fully satisfied with the treatment.

CONCLUSION

Results from this long-term follow-up suggest that implant-supported all-ceramic FDPs are an acceptable treatment alternative.

Nonvital Tooth Bleaching: A Case Discussion for the Clinical Practice

When clinicians embark on an esthetic treatment plan, teeth bleaching should be a primary consideration, regardless of whether the approach taken will be a conservative one or more prosthodontic. Tooth discolorations occur for various reasons, ranging from changes simply related to the age of the patient to those caused by trauma or tooth necrosis. In contemporary dentistry, by applying the proper protocol, sufficient results can be achieved with bleaching, even in many cases of root canal-treated discolored teeth. This article, which highlights a long-term case report, describes a protocol for nonvital bleaching of significantly discolored anterior teeth and offers numerous pragmatic tips for practitioners.