Influence of collar height of definitive restoration and type of luting cement on the amount of residual cement in implant restorations: A clinical study.

STATEMENT OF PROBLEM: Residual cement in the peri-implant sulcus may cause peri-implant mucositis, which can lead to peri-implantitis. Clinical studies comparing the role of the collar height of the definitive restoration and the type of cement used for luting the prosthesis in the amount of residual cement are lacking. PURPOSE: The purpose of this clinical study was to determine the volume of residual cement left undetected in the peri-implant sulcus by an implant prosthesis with 3 different collar heights and 3 luting cements. MATERIAL AND METHODS: Participants with single implants in the premolar region were divided into 3 groups of 10 according to the distance from the peri-implant soft tissue crest to the implant platform: group low collar (sulcus depth <2 mm), group medium collar (2-4 mm), and group high collar (>4 mm). A metal-ceramic crown with an occlusal opening was fabricated on a straight titanium abutment, which facilitated removal of the crown along with the abutment after cementation. The implant luting cements used were composite resin cement (RelyX U200), Type I glass ionomer cement (GC Gold Label 1), and zinc oxide noneugenol interim luting cement (RelyX Temp NE). The modified crown was cemented with 1 cement each during the impression, bisque evaluation, and definitive crown cementation appointments. The crown was retrieved, and the residual cement collected during each appointment. The measurements obtained were statistically analyzed with general linear model analysis followed by post hoc testing using the Bonferroni test (α=.05). RESULTS: Mean volume of the residual excess cement (mm3) formed in group low collar was 0.33 ±0.17, 0.26 ±0.17, and 0.08 ±0.08 for subgroups Resin, GIC, and ZNE, respectively. In group medium collar, it was 1.18 ±0.31, 1.08 ±0.3, and 0.61 ±0.32; and in group high collar, it was 2.33 ±0.31, 2.1 ±0.74, and 1.31 ±0.56 for the same subgroup, respectively. There was a statistically significant difference in the formation of REC between the collar height groups (P<.001). Among the luting cements, zinc oxide noneugenol cement produced significantly lower residual cement compared with the other 2 cements, and there was no statistically significant difference between the glass ionomer and resin cements (P>.05). CONCLUSIONS: The collar height of the definitive restoration and the type of luting cement play significant roles in the formation of residual cement in fixed implant-supported restorations.

Retention Strength of Zirconia Crowns Cemented onto PEEK Abutments Using Two Different Types of Resin Cement With or Without Primer Application-An In Vitro Study.

PURPOSE: To evaluate the retention of zirconia crowns on polyetheretherketone (PEEK) abutments using different luting agents, with and without PEEK primer. MATERIALS AND METHODS: A total of 100 PEEK abutment replicas were fabricated, airborne particle-abraded with aluminum oxide, and divided into four groups (n = 25). A total of 100 zirconia crowns were fabricated and cemented using either adhesive resin cement or self-adhesive resin cement with and without PEEK primer; thus, the groups were: group AA-P (adhesive cement with primer); group AA-N (adhesive cement without primer); group SA-P (self-adhesive cement with primer); and group SA-N (self-adhesive cement without primer). The specimens were thermocycled and subjected to crown pull-out tests. The values were recorded and analyzed using analysis of variance and post hoc analysis (α = .05). The mode of failure of debonded surfaces was evaluated using scanning electron microscopy. RESULTS: The pull-out force values were 3.13 ± 0.31 MPa for group AA-P, 1.77 ± 0.20 MPa for group AA-N, 2.10 ± 0.12 MPa for group SA-P, and 1.49 ± 0.18 MPa for group SA-N. Statistically significant differences were found between all four groups (P < .001). The specimens with PEEK primer applied showed higher values compared to nonprimed specimens for both cements tested. Scanning electron microscopy analysis showed more mixed failures for adhesive cement and more adhesive failures for self-adhesive resin cement. CONCLUSION: The maximum pull-out forces were recorded for zirconia crowns bonded to PEEK abutments with adhesive cement. The use of PEEK primer increased the pull-out values for both resin cements.

Randomized clinical trial of zirconia and polyetheretherketone implant abutments for single-tooth implant restorations: A 5-year evaluation.

STATEMENT OF PROBLEM: Titanium-supported polyetheretherketone (PEEK) abutments provide an economic alternative to zirconia abutments in esthetically important areas. Research comparing the performance regarding esthetics, longevity, and biologic parameters of PEEK abutments is lacking. PURPOSE: The purpose of this clinical study was to determine whether PEEK implant abutments provide similar esthetic and biologic parameters and survival rates as zirconia implant abutments. MATERIAL AND METHODS: Forty participants (age 20 to 50 years) receiving maxillary anterior and premolar implants were enrolled in the study and randomly assigned into 1 of 2 groups: Group PEEK (20 titanium-supported PEEK abutments) and group ZIR (20 zirconia abutments). Both groups were restored with pressed lithium disilicate ceramic crowns. Technical, biologic, and esthetic evaluation was performed at baseline and at 1, 3, and 5 years. The probing pocket depth, plaque control record, and bleeding on probing were recorded at the abutments (test) and compared with those at the corresponding contralateral teeth (control) and also between the 2 test groups. Standardized digital radiographs of the implants were made, and the bone level was recorded with the implant shoulder as the reference on the mesial and distal sides. The color difference between the peri-implant mucosa and control teeth gingiva and the discoloration of the implant crowns were determined with a spectrophotometer. The Student unpaired t test and repeated-measure ANOVA were used to statistically analyze the data (α=.05). RESULTS: From the 5-year evaluation, both PEEK and zirconia abutments with ceramic crowns showed 100% survival rate without any fracture or restoration loss. Differences in the biologic parameters of zirconia and PEEK abutments were statistically similar: mean probing pocket depth (group ZIR: 2.32 ±0.50 mm, group PEEK: 2.13 ±0.60 mm); mean plaque control record (group ZIR: 0.19 ±0.19, group PEEK: 0.15 ±0.17); and mean bleeding on probing (group ZIR: 0.12 ±0.11, group PEEK: 0.08 ±0.12). The mean marginal bone loss at 5 years was similar for implants supporting zirconia and PEEK abutments: mean mesial bone level (group ZIR: 1.8 ±0.5 mm; group PEEK: 1.9 ±0.6 mm), and mean distal bone level (group ZIR: 1.7 ±0.6 mm, group PEEK: 1.8 ±0.3 mm). The initial color difference (ΔE) between the peri-implant mucosa and gingiva of the analogous contralateral teeth diminished over time. No discoloration of the definitive restoration supported by PEEK or zirconia was detected over 5 years. CONCLUSIONS: At the 5-year evaluation, zirconia and PEEK abutments exhibited the same survival rate with similar biologic and esthetic outcomes.

The effect of metallic dental restorations and implants in causing patient discomfort and artefacts during magnetic resonance imaging of the head and neck.

Context: Patients with metallic dental objects in their oral cavity are often associated with discomfort or artefacts during magnetic resonance imaging (MRI) of the head and neck. Aim: This study was conducted to evaluate the effects of metallic dental objects in causing patient discomfort and artefacts during MRI of the head and neck region. Design: This is an observational study including 538 participants from various specialized MRI centres in Kozhikode. Methods and Material: MRI records of 538 participants who underwent head and neck MRI as a part of their medical treatment were collected. With the help of questionnaire and clinical examination, the type of metallic dental object in the patient's oral cavity was identified. After examining the MRI images, four categories of artefacts were established. In MRI brain, artefacts in three different sequences were also studied. Statistical Analysis Used: The significance of the difference between proportions was analysed by the Chi-square test. Results: Artefacts were found in 65 cases with metallic dental objects but none of the participants had experienced any kind of discomfort. The artefact formation significantly depended on the type of metallic dental restoration in the patient's oral cavity. Orthodontic braces and titanium bone plate created severe artefacts in head and neck MRI making interpretation almost impossible. In the MRI brain, diffusion-weighted imaging is most sensitive to artefact followed by fluid-attenuated inversion recovery. Conclusions: Artefacts were found in 65 cases with metallic dental restorations but none of the participants had experienced any kind of discomfort.