Quintessence International, 08/2013

Translucent zirconia modifications offer esthetic improvement for manually veneered zirconia structures, as they do not lead to a shining through of the substructure material, even in cases with a pronounced anatomic core design for maximum support of the veneering ceramics. Moreover, these zirconia modifications allow the production of fully anatomic zirconia crowns and fixed dental prostheses in the posterior region. The clinical advantage of these restorations is defined by a significantly reduced material thickness in comparison with veneered restorations or other monolithic materials. As the restoration can be colored individually prior to sintering, followed by characterization by staining, good esthetic results in the posterior region are achieved, even in cases with substantially reduced space. The results of laboratory studies performed so far seem to justify the clinical application of fully anatomic restorations. However, additional clinical studies are required to support these new material modifications. Keywords: abrasion, all-ceramic, chipping, monolithic ceramics, zirconia

Objective: In recent years, periodontal disease has been related to a large number of systemic disorders. The aim of this study was to find a relationship between periodontal disease and venous thromboembolic disease. Method and Materials: A total of 197 patients were included in the study, 97 patients with a diagnosis of venous thromboembolic disease and 100 healthy controls, in order to establish an association between these two conditions. All patients were subjected to periodontal examination, with evaluation of the number of teeth, Bleeding Index, Gingival Index, Simplified Oral Hygiene Index, Community Periodontal Index of Treatment Needs, Clinical Attachment Level, Probing Pocket Depth, number of pockets >= 4 mm, and number of pockets >= 6 mm. Results: A high prevalence of periodontal disease was detected in patients with thromboembolic disease (P .001). Bleeding Index, Gingival Index, Simplified Oral Hygiene Index, Clinical Attachment Level, and Probing Pocket Depth were higher in venous thromboembolic disease patients than in the control group (P .001). Conclusion: A high prevalence of periodontal disease was detected in venous thromboembolic patients. There exists an association between periodontal disease and venous thromboembolic disease. Keywords: periodontal disease, venous thromboembolic disease

Objective: To evaluate the changes in the clinical parameters, and the prevalence and quantities of three major periodontopathic bacteria, namely Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Tannerella forsythia, in subgingival plaque collected from patients with generalized chronic periodontitis (GCP) or generalized aggressive periodontitis (GAgP) in response to nonsurgical periodontal therapy. Method and Materials: 73 GCP patients and 57 GAgP patients were enrolled in this study. Clinical parameters, including probing depth (PD), clinical attachment loss (CAL), and Sulcus Bleeding Index (SBI) were measured. The prevalence and quantities of the three bacteria collected from the subgingival plaque were detected by real-time PCR. Both clinical and microbiologic parameters were evaluated at baseline, 4, and 12 weeks after the nonsurgical periodontal treatment. Results: PD, CAL, and SBI were significantly improved in GCP and GAgP groups at 4 and 12 weeks after nonsurgical periodontal therapy, compared to the baseline levels. The prevalence and quantities of P gingivalis in GCP at baseline (82.19% and 3.35E+5) were statistically higher than those found in GAgP (66.67% and 1.08E+5; P .05). After therapy, the prevalence and quantities of the three bacteria were sufficiently reduced in both groups at 4 and 12 weeks. There was no significant difference in improvement of clinical and microbiologic parameters between the GCP and GAgP patients after treatment. Conclusion: There was a difference in P gingivalis prevalence and quantity between the GCP and GAgP patients at baseline. In addition, nonsurgical periodontal therapy was effective in the treatment of clinical symptoms and the major periodontopathic bacterial control between GCP and GAgP patients. Keywords: aggressive periodontitis, chronic periodontitis, nonsurgical periodontal therapy

Purpose: Two commonly used attachment systems for implant-retained overdentures are bar and ball systems. The aim of this study was to compare these two types of attachments on the basis of the stresses introduced to the mandibular posterior residual ridge by an overdenture retained by two implants. Method and Materials: A basic model was generated from the data provided by a CT scan of a patient's mandible, the diagnostic casts, and the existing overdenture. Two root-form implants were placed in the anterior mandible. Models were used to simulate two situations: The first model represented an edentulous mandible supporting an overdenture retained by two implants connected with a bar and plastic clip system, and in the second model two ball attachments with nylon caps were used as the retention mechanism. A 35 N vertical load was introduced to the first molar region of each group to simulate the occlusal forces of the maxillary complete denture. The stresses in the mandibular residual ridges under the first molar region were measured using Ansys software. Results: The bar-retained overdenture introduced higher stresses to the posterior mandibular residual ridge compared to the ball-retained overdenture (0.4 MPa and 0.1 MPa, respectively). Conclusion: Within the limitations of this study, the ball system was shown to introduce a lower amount of stress to the posterior mandibular residual ridge compared to a bar and clip system. Keywords: ball attachment, bar attachment, finite element analysis, mandibular implant-retained overdenture, posterior residual ridge

Objective: To test the shear bond strength of self-adhesive and conventional resin cements to zirconia after the application of different types of silanes with/without aging. Method and Materials: Three hundred and sixty zirconia specimens were randomized into 10 groups (n = 36). Five groups were assigned to the self-adhesive resin cement RelyX-Unicem (RXU) and five groups to the conventional resin cement Panavia 21 (PAN). The groups were further assigned to the following pretreatments: Monobond-S (M), Alloy Primer (AP), Clearfil (C), Experimental Universal Primer (EUP), or without silane (control group). Twelve specimens of each of the cements were tested after water storage for 24 hours (initial shear bond strength). The remaining 24 samples were aged (1,500 cycles, n = 12; or 13,500 cycles, n = 12). The shear bond strength was measured (Universal Testing Machine; 1 mm/min, Zwick Roell Z010). Data were analyzed with one-way ANOVA followed by post-hoc Scheffé tests. Student's t test was applied to test the differences between the two cements (P .05). Results: The initial bond strength of RXU was increased by the application of the different silanes. The silanes had less influence on the initial bond strength of PAN. Aging reduced the bond strength of RXU significantly in combination with two of the silanes (AP, 0 ± 0 MPa; C, 4.1 ± 0.9 MPa; P .05). Aging led to a significant reduction of the bond strength values of PAN with the primers AP (2.9 ± 0.4 MPa) and EUP (2.5 ± 0.5 MPa; P .05). Conclusion: The present study indicates that the bond strength of the self-adhesive resin cement was positively influenced by the pretreatment of the zirconia surface with different silanes. Aging led to a decrease of the bond strength of both types of cements, irrespective of most of the silanes used. Keywords: aging, pretreatment, resin cements, self-adhesive resin cement, shear bond strength, silane, universal silane, zirconia

Objective: The aim of this clinical study was to compare tooth shade, color rebound, and tooth sensitivity after using either a combined bleaching technique (CBT) or a deep bleaching technique (DBT) to lighten stained teeth. CBT is a two-stage bleaching process consisting of an initial in-office bleaching treatment session using 35% hydrogen peroxide (HP) followed by a 7-day at-home bleaching session with 6% HP. DBT involves a 7-day at-home bleaching session with 6% HP prior to the initiation of a two-stage CBT process. Method and Materials: Thirty-six volunteers were recruited in this split-mouth design randomized clinical trial. Tooth shade was objectively evaluated by using a spectrophotom-eter and shade guide tabs. Tooth and gingival tissue sensitivity were self-evaluated by recording any tooth or gingival sensitivity on a daily basis. Results: Both CBT and DBT presented satisfactory whitening effects. Although DBT resulted in a better shade change, the two bleaching techniques had a similar rebound effect. CBT was associated with a lower frequency of tooth sensitivity, but both bleaching techniques can be considered safe from a clinical standpoint. Conclusion: The results indicate that CBT might potentially be preferred to whiten teeth, thus promoting the shade change, and avoiding gingival and tooth sensitivity. Keywords: combined bleaching technique, deep bleaching technique, randomized controlled trial, tooth bleaching

Objective: Recent review articles have shown that open debridement is more effective in the treatment of peri-implantitis than closed therapy. However, surgery may result in marginal recession and compromise esthetics. The purpose of this study was to assess the efficacy of nonsurgical antimicrobial photodynamic therapy (aPDT) in moderate vs severe defects. Method and Materials: The study encompassed 16 patients with a total of 18 ailing implants. Ten of these implants showed moderate bone loss ( 5 mm; Group 1) and eight implants severe defects (5 through 8 mm; Group 2). All implants received aPDT without surgical intervention. At baseline and 2 weeks, 3 months, and 6 months after therapy, peri-implant health was assessed including sulcus bleeding index (SBI), probing depth (PD), distance from implant shoulder to marginal mucosa (DIM), and clinical attachment level (CAL). Radiographic evaluation of distance from implant to bone (DIB) allowed comparison of peri-implant hard tissues after 6 months. Results: Baseline values for SBI were comparable in both groups. Three months after therapy, in both groups, SBI and CAL decreased significantly. In contrast, after 6 months, CAL and DIB increased significantly in Group 2, not in Group 1. However, DIM-values were not statistically different 6 months after therapy in both groups. Conclusion: Within the limits of this 6-month study, nonsurgical aPDT could stop bone resorption in moderate peri-implant defects but not in severe defects. However, marginal tissue recession was not significantly different in both groups at the end of the study. Therefore, especially in esthetically important sites, surgical treatment of severe peri-implantitis defects seems to remain mandatory. Keywords: antibacterial photodynamic therapy, laser, peri-implantitis

Objective: Color perception is an important variable in detecting and assessing oral conditions. The aim was to investigate clinicians' perception of toluidine blue (Tblue) staining compared to digital color analysis, which may impact mucosal lesion detection, affect the decision to biopsy, and biopsy site selection. Method and Materials: Four oral lesions were stained with Tblue. Digital color analyses of eight areas on each image were completed and were considered as "gold standard" (GS). Twenty specialists ranked these areas according to their perceived intensity of blue stain in two sessions. Results: Consistency between GS and observers rankings was 0.8791. However, more than half of the observers inaccurately perceived the intermediate blue tones. Overall interobserver agreement was 0.8714; stability between two sessions decreased to 45% for intermediate tones. Conclusion: Assessing the equivocal blueness of an oral mucosal lesion in clinical settings may vary due to variation in visual perception. A digital method for objective color analysis in clinical practice may be used to eliminate this deficiency by implementing a mathematical formula. Keywords: color perception, oral cancer, oral diagnosis, oral medicine, toluidine blue

Iatrogenic trauma can be defined as any adverse condition in a patient resulting from treatment by a physician or dentist. Orthodontic treatment carries with it the risks of tissue damage and treatment failure. The aim of this article is to present traumatic oral tissue lesions resulting from iatrogenic orthodontic origin with a 2-year follow-up period based on orthodontic intervention followed by periodontal surgery. The management of traumatic injuries is dependent on the severity of the involvement of the periodontal tissues. While, in most cases, the elimination of the offending agent and symptomatic therapy is sufficient, in severe cases, or when the injury resulted in permanent defects, periodontal/regenerative therapy may be necessary. The dentist must be aware of these risks in order to help the patient make a fully informed choice whether to proceed with orthodontic treatment. The skill, experience, and up-to-date knowledge of dentists are the main factors to prevent possible iatrogenic traumas. Keywords: dental injury, dental trauma, iatrogenic trauma, orthodontic treatment