Cemented versus screw-retained zirconia-based single-implant restorations: 5-year results of a randomized controlled clinical trial

OBJECTIVES To compare cemented and screw-retained one-piece zirconia-based restorations in terms of clinical, radiographic, and technical outcomes 5 years after insertion. MATERIALS AND METHODS Thirty-four patients with single-tooth implants were randomly restored with either a cemented lithium disilicate crown on a one-piece customized zirconia abutment (CEM, 17 patients) or a screw-retained crown based on a directly veneered one-piece customized zirconia abutment (SCREW, 16 patients). All patients were recalled for a baseline examination (7-10 days after crown insertion) and then annually up to 5 years. The following outcomes were assessed: marginal bone level (changes), technical, and clinical (bleeding on probing, plaque control record, probing depth, and keratinized tissue) parameters. The Mann-Whitney U-test was used to assess differences between the two groups. RESULTS At 5 years, 26 patients (13 in each group) were re-examined. The survival rates on the implant and restorative levels were 100% and 82.4% (equally for both groups), respectively. At 5 years, the median marginal bone level was located at -0.15 mm (IQR: -0.89 mm; 0.27 mm) (CEM) and -0.26 mm (IQR: -0.38 mm; 0.01 mm) (SCREW) below the implant shoulder (intergroup p = .9598). The median changes between baseline and the 5-year follow-up amounted to -0.23 mm (CEM; intragroup p = .0002) and -0.15 mm (SCREW; intragroup p = .1465) (intergroup p = .1690). The overall technical complication rate at 5 years was 15.4% (CEM) and 15.4% (SCREW) (intergroup p = 1.00). Clinical parameters remained stable over time (baseline to 5 years). CONCLUSIONS At 5 years, screw-retained and cemented restorations rendered largely the same clinical, technical, and radiographic outcomes. Technical complications were frequent in both groups

A randomized controlled clinical trial comparing small buccal dehiscence defects around dental implants treated with guided bone regeneration or left for spontaneous healing

PURPOSE The aim of the present randomized controlled clinical study was to test whether small bony dehiscence defects (≤5 mm) left to heal spontaneously result in the same clinical and radiological outcome as defects treated with guided bone regeneration (GBR). MATERIALS AND METHODS Twenty-two patients who received at least one implant with a small bony dehiscence defect were enrolled in the study. If the defect height was ≤5 mm, the site was randomly assigned to either the spontaneous healing (SH) group or the GBR group. In the SH group, the defect was left without any treatment. In the GBR group, the defects around the implants were grafted with deproteinized bovine bone mineral (DBBM) and covered with a native collagen membrane. Clinical and radiographic measurements were performed 6 months after implant placement with a reentry surgery and at the time of crown insertion and the subsequent follow-up appointments at 3, 6, 12 and 18 months after loading. For statistical analyses, the mixed linear model was applied for the clinical and radiographic measurements observed around the implants. Simple comparisons of the location of the measurements in the two independent groups are performed with the Mann-Whitney U-test. In addition, the mixed model assumptions were checked. RESULTS The implant and crown survival rate 18 months after loading was 100%, revealing no serious biologic or prosthetic complication. The mean changes of the buccal vertical bone height between implant placement and reentry surgery after 6 months revealed a small bone loss of -0.17 ± 1.79 mm (minimum -4 mm and maximum 2.5 mm) for the SH group and a bone gain of 1.79 ± 2.24 mm (minimum of -2.5 mm and maximum of 5 mm) for the GBR group, respectively (P = 0.017). Radiographic measurements demonstrated a slight bone loss of -0.39 ± 0.49 mm for the SH group and a stable bone level of 0.02 ± 0.48 mm for GBR group after 18 months. All peri-implant soft tissue parameters revealed healthy tissues with no difference between the two groups. CONCLUSION Small bony dehiscence defects left for spontaneous healing demonstrated high implant survival rates with healthy and stable soft tissues. However, they revealed more vertical bone loss at the buccal aspect 6 months after implant insertion and also more marginal bone loss between crown insertion and 18 months after loading compared to sites treated with GBR

Effect of different intraradicular posts on the color of the buccal gingiva at teeth restored with zirconia crowns

The purpose of this study was to test whether prosthetic treatment with different intraradicular posts influences the color of the buccal gingiva at teeth restored with zirconia crowns. A total of 31 patients in need of a full-coverage single crown at an endodontically treated premolar, canine, or incisor in the maxilla or the mandible were included. The patients were randomly assigned to receive composite build-ups using titanium (Ti), zirconia (Zi), or glass-fiber (Gf) posts or a build-up using no post at all (NP). All the teeth were restored with veneered zirconia single crowns. Spectrophotometric color measurements of the buccal gingiva were taken at the test teeth prior to and after the prosthetic treatment, and at the contralateral vital control tooth. The differences of the color components ΔL, Δa, and Δb and the total color difference ΔE between the test tooth prior to and after treatment and between the test and control tooth were calculated. The color differences were analyzed to determine whether they varied from 0 and 3.7, the threshold for detection by the human eye. Analysis of variance was performed to compare ΔE, ΔL, Δa, and Δb in the four post groups. The prosthetic treatment induced a significant color change ΔE in all the groups (Ti: ΔE1 = 6.4 ± 1.9; Zi: 7.1 ± 2.0; Gf: 6.2 ± 3.5; NP: 6.6 ± 3.5). There was no significant difference between Ti, Zi, Gf, and NP with respect to ΔE, ΔL, Δa, and Δb. Gingival color ΔE differed significantly between the test and control teeth before (Ti: ΔE = 6.8 ± 3.0; Zi: 9.0 ± 3.5; Gf: 5.7 ± 2.1; NP: 8.2 ± 2.8) and after prosthetic treatment (Ti: ΔE = 6.0 ± 2.8; Zi: 7.1 ± 2.9; Gf: 7.2 ± 3.0; NP: 6.9 ± 2.6). The use of different intraradicular posts (titanium, zirconia, glass fiber) or no post at all did not influence the color of the buccal gingiva at teeth restored with zirconia crowns. There was a significant gingival color difference between endodontically treated teeth and vital control teeth, both before and after prosthetic treatment

Minimally invasive rehabilitation of a patient with amelogenesis imperfecta

This case report describes a minimally invasive step-by-step approach to treat a patient with amelogenesis imperfecta. This is a genetic developmental disorder of the dental enamel, which clinically manifests as white and dark discolorations of the teeth. The clinical examination did not reveal the true depth of the staining. Therefore, a step-wise treatment approach was chosen. The first step consisted of a home bleaching procedure, which led to a slight improvement of the esthetic appearance, but the stains were still clearly visible. The next step was the application of a microabrasion technique. This led to further improvement, but not to a satisfactory result for this patient who had high esthetic expectations. Thus, the third step was undertaken: it was planned to restore the maxillary incisors and canines with ceramic veneers. The dental technician prepared a wax-up, which served as a basis for a clinical mock-up. After discussing the mock-up and the treatment plan with the patient, crown lengthening was performed on teeth 11 and 23 to improve the pink esthetics. Subsequently, the teeth were prepared in a minimally invasive way and a final impression was taken. Following try-in, the six veneers were inserted with resin cement

Influence of beveling and ultrasound application on marginal adaptation of box-only Class II (slot) resin composite restorations

A laboratory study was performed to assess the influence of beveling the margins of cavities and the effects on marginal adaptation of the application of ultrasound during setting and initial light curing. After minimal access cavities had been prepared with an 80 microm diamond bur, 80 box-only Class II cavities were prepared mesially and distally in 40 extracted human molars using four different oscillating diamond coated instruments: (A) a U-shaped PCS insert as the non-beveled control (EMS), (B) Bevelshape (Intensiv), (C) SonicSys (KaVo) and (D) SuperPrep (KaVo). In groups B-D, the time taken for additional bevel finishing was measured. The cavities were filled with a hybrid composite material in three increments. Ultrasound was also applied to one cavity per tooth before and during initial light curing (10 seconds). The specimens were subjected to thermomechanical stress in a computer-controlled masticator device. Marginal quality was assessed by scanning electron microscopy and the results were compared statistically. The additional time required for finishing was B > D > C (p < or = 0.05). In all groups, thermomechanical loading resulted in a decrease in marginal quality. Beveling resulted in higher values for "continuous" margins compared with that of the unbeveled controls. The latter showed better marginal quality at the axial walls when ultrasound was used. Beveling seems essential for good marginal adaptation but requires more preparation time. The use of ultrasonic vibrations may improve the marginal quality of unbeveled fillings and warrants further investigation

Effect of the color of intraradicular posts on the color of buccal gingiva: a clinical spectophotometric evaluation

The primary aim of this study was to test whether intraradicular posts of different colors induce different amounts of color change of the buccal gingiva. Twentythree patients in need of a post-and-core buildup at one endodontically treated incisor, canine, or premolar were included. Titanium (Ti), zirconia (Zi), and glass fiber (Gf) posts were consecutively inserted in each test tooth. Spectrophotometric color measuremement of the buccal gingiva was performed prior to post bed preparation and after insertion of Ti, Zi, and Gf posts. For control purposes, the gingival color at the contralateral vital tooth was assessed. The differences of color components ΔL, Δa, and Δb and the total color difference (ΔE) between different experimental conditions were obtained. ΔE value of 3.7 was considered the threshold value for intraoral color distinction. The gingival thickness at test teeth was measured. No difference occurred with regard to the amount of gingival discoloration induced by different posts. In the majority of cases, posts did not exhibit a visible influence on the color of buccal gingiva. The gingiva at endodontically treated teeth presented a visible discoloration compared to the gingiva at vital teeth. The degree of gingival discoloration at endodontically treated teeth was correlated with the gingival thickness, with more pronounced discolorations in cases of thinner soft tissue

Effect of Different Intraradicular Posts on the Color of the Buccal Gingiva at Teeth Restored with Zirconia Crowns

The purpose of this study was to test whether prosthetic treatment with different intraradicular posts influences the color of the buccal gingiva at teeth restored with zirconia crowns. A total of 31 patients in need of a full-coverage single crown at an endodontically treated premolar, canine, or incisor in the maxilla or the mandible were included. The patients were randomly assigned to receive composite build-ups using titanium (Ti), zirconia (Zi), or glass-fiber (Gf) posts or a build-up using no post at all (NP). All the teeth were restored with veneered zirconia single crowns. Spectrophotometric color measurements of the buccal gingiva were taken at the test teeth prior to and after the prosthetic treatment, and at the contralateral vital control tooth. The differences of the color components ΔL, Δa, and Δb and the total color difference ΔE between the test tooth prior to and after treatment and between the test and control tooth were calculated. The color differences were analyzed to determine whether they varied from 0 and 3.7, the threshold for detection by the human eye. Analysis of variance was performed to compare ΔE, ΔL, Δa, and Δb in the four post groups. The prosthetic treatment induced a significant color change ΔE in all the groups (Ti: ΔE1 = 6.4 ± 1.9; Zi: 7.1 ± 2.0; Gf: 6.2 ± 3.5; NP: 6.6 ± 3.5). There was no significant difference between Ti, Zi, Gf, and NP with respect to ΔE, ΔL, Δa, and Δb. Gingival color ΔE differed significantly between the test and control teeth before (Ti: ΔE = 6.8 ± 3.0; Zi: 9.0 ± 3.5; Gf: 5.7 ± 2.1; NP: 8.2 ± 2.8) and after prosthetic treatment (Ti: ΔE = 6.0 ± 2.8; Zi: 7.1 ± 2.9; Gf: 7.2 ± 3.0; NP: 6.9 ± 2.6). The use of different intraradicular posts (titanium, zirconia, glass fiber) or no post at all did not influence the color of the buccal gingiva at teeth restored with zirconia crowns. There was a significant gingival color difference between endodontically treated teeth and vital control teeth, both before and after prosthetic treatment

Randomized Controlled Clinical Trial Comparing Cemented Versus Screw-Retained Single Crowns on Customized Zirconia Abutments: 3-Year Results

PURPOSE To assess the biologic and technical responses to cemented and screw-retained all-ceramic single-tooth implant-supported reconstructions at 3 years postinsertion. MATERIALS AND METHODS Thirty-four patients with single-tooth implants were randomly restored with either a cemented lithium disilicate crown on a customized zirconia abutment (CEM) or a screw-retained crown with a directly veneered zirconia abutment (SCREW). At baseline examination and after 3 years of loading, marginal bone level and technical parameters were assessed. Differences in marginal bone loss were tested using Mann-Whitney U test at baseline and at 3 years, and changes within each group between baseline and 3 years were tested using Wilcoxon signed rank test. RESULTS The median changes between baseline and the 3-year follow-up amounted to -0.1 mm (CEM; intragroup P = .36) and -0.0 mm (SCREW; intragroup P = .58). Intergroup comparisons did not reveal statistically significant differences at 3 years (P = .20) or over time (P = .70). CONCLUSION At 3 years, screw-retained and cemented reconstructions rendered largely the same radiographic and technical outcomes

Early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single crowns

To assess the early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single-tooth implant-supported reconstructions

Early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single crowns

OBJECTIVES To assess the early histological, microbiological, radiological, and clinical response to cemented and screw-retained all-ceramic single-tooth implant-supported reconstructions. MATERIALS AND METHODS Patients with single-tooth implants were randomly allocated to receive a cemented lithium disilicate crown on a customized zirconia abutment (CEM) or a screw-retained crown with a directly veneered zirconia abutment (SCREW). At the screening visit, at crown insertion and at the 6-month follow-up, clinical parameters were measured at the implant and the contralateral tooth. Marginal bone levels, technical parameters, and esthetic outcomes were measured at the implants. At the 6-month follow-up, a microbiological test was performed and a soft tissue biopsy was harvested at the implants for histological analysis. Inflammatory cells and fibroblasts/-cytes were analyzed at the level of the sulcular epithelium, junctional epithelium, and connective tissue. The histological parameters were analyzed by means of a linear mixed model. RESULTS Thirty-three patients completed the study, and implant and crown survival rates were 100% at 6 months. Histologically, the number of inflammatory cells tended to be higher in group CEM (p > 0.05). Moreover, significantly less inflammatory cells and fibroblasts/-cytes were found in the sulcular epithelium compared to the junctional epithelium and supracrestal connective tissue (p < 0.001). Four patients were tested positive for periodontal marker pathogens at the 6-month follow-up, and three of them belonged to group CEM. From crown insertion to the 6-month follow-up, median marginal bone levels changed only minimally and measured 0.31 and 0.32 mm in group CEM and 0.47 and 0.36 mm in group SCREW, respectively. Clinical and esthetic parameters remained stable over time and were comparable between natural teeth and implants as well as between the groups. CONCLUSIONS Cemented reconstructions were associated with more inflammatory cells, and more patients were diagnosed with periodonto-pathogens. Both types of reconstructions resulted in similar radiological (marginal bone levels) and clinical outcomes (bleeding on probing and probing depth)