Recurrence Rate of Proximal Contact Loss Between Implant Restorations and Adjacent Teeth After Proximal Contact Repair: A Retrospective Study.

PURPOSE: Proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDPs) and adjacent teeth has been reported as a common complication of implant therapy. The prevalence of PCL and its potential risk factors have been extensively studied. However, few studies have discussed the recurrent PCL after intervention to restore the proximal contacts. Thus, this retrospective study aimed to evaluate the recurrence rate of PCL and its potential risk factors. MATERIALS AND METHODS: This study included 41 patients (with 45 implants in the posterior region), who had experienced PCL between implant restorations and adjacent teeth and had received contact repair. Recurrent PCL was recorded and evaluated during routine follow-ups with an interval of 6 to 12 months. The recurrence rates and time were measured. The potential influential factors of PCL were also assessed. Fisher exact test, t test, univariate logistic regression analyses, and multivariate logistic regression model were utilized to identify factors influencing PCL. RESULTS: The recurrence rates of mesial PCL were high (> 50%) and the recurrence time became progressively rapid after each repair (5, 3.2, and 2.2 years). Implants with the first PCL recurrence were more likely to be splinted than those implants without recurrence (54.5% vs 18.8%; P = .032). In addition, patients with the first recurrence were slightly older than those without recurrence (55.8 vs 50.1 years; P = .087). Age, implant restoration (splinted vs single), frequent use of interdental brushes, and time to first complaint were the candidate factors associated with recurrent PCL in the univariate logistic regression analysis. The multivariate logistic regression model revealed that only splinted implant restoration was independently associated with a higher risk of recurrence (odds ratio 4.99; 95% confidence interval 1.02-24.31; P = .047). CONCLUSION: The recurrence rates of mesial PCL were high and associated with the splinted-type design. Also, the recurrence time of PCL accelerated after each repair. Therefore, routine follow-up monitoring PCL and carefully assessing patient compliance after implant therapy are recommended.

Comparison of the residual cement on custom computer-aided design and computer-aided manufacturing titanium and zirconia abutments: A preliminary cohort study.

STATEMENT OF PROBLEM: Clinical studies comparing the occurrence and quality of residual cement between custom zirconia and custom titanium abutments with subgingival margins are scarce. PURPOSE: The purpose of this clinical study was to assess the difference in the amount of residual cement between custom zirconia and titanium abutments with a 1-mm subgingival margin. MATERIAL AND METHODS: Eighty participants were randomized to receive either a custom zirconia abutment with a bonded titanium insert or a custom titanium abutment with a 1-mm subgingival margin on a posterior bone-level implant. Monolithic lithium disilicate crowns with a screw-access hole were cemented to abutments randomly with either a resin-modified glass ionomer cement or a resin cement. After cementation, the crown-abutment assemblies were removed and photographed from the mesial, buccal, distal, and lingual of the specimen to record the residual cement. The length along the abutment margin of each aspect of the assembly was measured. The surface area of the residual cement (SA) and the surface area of the residual cement per unit length of margin (SA_P) were calculated. Results for the groups were compared with the Fisher exact test, the Friedman test, and the Mann-Whitney U test (α=.05). RESULTS: The median (lower quartile, upper quartile) of SA and SA_P for the custom zirconia abutment with a bonded titanium insert was 1.9 (0.5, 3.9) mm2 and 0.086 (0.032, 0.02) mm2, respectively, and for the custom titanium abutment, the values were 2.9 (1.3, 5.1) mm2 and 0.138 (0.062, 0.239) mm2, respectively. No significant difference was found between the custom zirconia abutments with bonded titanium inserts and titanium abutments for SA (P=.075) and SA_P (P=.083) with the Mann-Whitney U test. No significant difference was found in residual cement between the 4 aspects of the abutment (SA: P=.852; SA_P: P=.954) with the Friedman test and between the 2 types of cement (SA: P=.447; SA_P: P=.878) with the Mann-Whitney U test. CONCLUSIONS: A similar amount of subgingival residual cement was recorded around the abutment-crown assembly, regardless of the abutment material or cement type used.

Calcitriol and enamel matrix derivative differentially regulated cemento-induction and mineralization in human periodontal ligament-derived cells.

BACKGROUND: Alveolar bone and cementum share many biological and developmental similarities. The mineralizing effect of calcitriol has been previously reported. Yet, its cemento-inductivity has not been confirmed. This study evaluated the potential cemento-inductivity effect of calcitriol and enamel matrix derivative (EMD) on human periodontal ligament-derived cells (hPDLCs). METHODS: The hPDLCs obtained from extracted third molars or premolars were cultured with calcitriol, or EMD. Cementogenic gene expression was examined using real-time quantitative reverse transcription polymerase chain reaction. Expression analysis also included cementoblast-specific markers, cementum protein 1 (CEMP1), cementum attachment protein (CAP), and recently reported cementoblast-enriched genes, secreted frizzled related protein 1 (SFRP1), and Dickkopf-related protein 1 (DKK1). Mineralization capacities were evaluated by alkaline phosphatase (ALP) activity, Alizarin Red, and Von Kossa staining followed by scanning electron microscope imaging and element mapping. RESULTS: Among tested conditions, 10 nM calcitriol enhanced most cementogenic gene expression, transforming growth factor-ß1, bone morphogenetic proteins (BMP-2 and BMP-4), core-binding factor subunit alpha-1/Runt-related transcription factor 2, Type I collagen, ALP, bone sialoprotein, osteopontin), osteocalcin, CEMP1, and CAP, and Wnt signaling negative modulators, SFRP1 and DKK1, along with highest ALP activity and mineralization formation in hPDLCs. However, only moderate CEMP1 protein was observed. In contrast, EMD stimulated stronger CEMP1 and CAP protein, but presented weaker mineralization capacity, hinting at the possibility that strong stimulation of mineralization might dominate cemetogenic specific factors and vice versa. CONCLUSIONS: Calcitriol demonstrated not only great osteoinductivity, but also the potential to induce cementogenic gene expression by initiating hPDLC differentiation and promoting mineralization. Compared with calcitriol, EMD promoted cemento-inductivity in hPDLCs at a later time point via highly expressed CEMP1 and CAP protein, but with less mineralization. Thus, calcitriol and EMD could provide differential enhancement of cemento-induction and mineralization, likely acting at various differentiation stages.

Retrospective comparison of posterior fixed dental prostheses supported by two different titanium abutments on tissue level implants.

STATEMENT OF PROBLEM: Clinical studies comparing compatible computer-aided design and computer-aided manufacturing (CAD-CAM) titanium abutments (CAs) and original prefabricated 1-piece titanium abutments (PAs) for posterior fixed dental prostheses (FDPs) on Straumann Tissue Level (STL) implants are sparse. PURPOSE: The purpose of this retrospective clinical study was to compare the performance of posterior FDPs supported by CAs and PAs on STL implants after a mean observation period of 7.2 years. MATERIAL AND METHODS: Patients who received STL implants and posterior FDPs by using CAs or PAs between January 2002 and December 2012 and returned for follow-up between January 2017 and September 2018 were included in this study. Technical and biological complications of FDPs were examined and recorded. Radiographs were used for the measurement of marginal bone loss (MBL) of each implant. Variables, complication rates, and MBL of the 2 groups were analyzed by using a generalized estimating equation and multivariable linear mixed model. RESULTS: Ninety-nine patients with 195 implants in the CA group and 75 patients with 143 implants in the PA group were included. The mean functional time of FDPs was 6.5 ±1.1 years for the CA group and 8.1 ±2.6 years for the PA group. No implant failure was noted in either group. The technical complication rate was 20.8% in the CA group and 26.3% in the PA group. Abutment screw loosening (ASL) was noted in the CA group (8.5%). The decementation rate was significantly higher in the PA group (14.1%) than that in the CA group (3.1%) (adjusted odds ratio=4.40, confidence interval=1.41 to 13.69, P=.011). No significant differences were found between the 2 groups in terms of the rates of ceramic chipping, peri-implantitis, peri-implant mucositis, or mean MBL. CONCLUSIONS: Using CAs or PAs to support posterior FDPs on STL implants has no significant effect on the incidence rate of biological complications. However, a higher ASL rate and a lower decementation rate were noted with CAs than with PAs.

The prevalence and associated factors of proximal contact loss between implant restoration and adjacent tooth after function: A retrospective study.

BACKGROUND: Dental implant is widely used as a treatment for missing teeth. However, proximal contact loss (PCL) between implant-supported fixed dental prostheses (FDP) and adjacent teeth has been reported as one of the common and adverse complications. PURPOSE: We aimed to evaluate the prevalence of PCL up to 18 years after implant prosthesis delivery and to analyze associated factors. MATERIALS AND METHODS: A total of 317 patients who had received implant FDP at the posterior regions were included in this study. Nineteen factors were assessed, including degrees of proximal contact tightness, oral hygiene, periodontal conditions, and food impaction. Chi-square test, univariate generalized estimating equation (GEE), and multivariate GEE were utilized to identify factors influencing PCL. RESULTS: Proximal contacts at both the mesial and distal (if present) sides were evaluated. The mesial contact loss rate (27%) was significantly higher than that of the distal contact loss (5%). Increased PCL rates over functional time were observed at both the mesial and distal sides. Six factors, including patient age, implant functional years, frequent use of interdental brushes, splinting or single implant, plunger cusp, and food impaction, were revealed to be associated with the mesial PCL using the chi-square test and univariate GEE analysis. However, only functional years (>5 years), frequent use of interdental brushes and food impaction showed significance in the multivariate GEE. CONCLUSIONS: Mesial PCL was frequent and increased over functional years. An occlusal retainer and routine follow-up may help prevent PCL. Although oral hygiene conditions contribute little to PCL, food impaction and frequent use of interdental brushes were influential factors.

The correspondence of 3D supporting bone loss and crown-to-root ratio to periodontitis classification.

AIM: Assessing the application of three-dimensional clinical attachment loss (3D-CAL), 3D supporting bone loss (3D-SBL), supracrestal tissue attachment (STA), and crown-to-root ratio (CRR) in evaluating the 2017 periodontitis classification. MATERIALS AND METHODS: We analysed ninety single-rooted human premolars with micro-computed tomography. The amount of 3D-SBL, linear radiographic bone loss (RBL), and CRR corresponding to various periodontitis stages as well as the statistical significance was investigated. RESULTS: From a 3D perspective, the premolars with a 21% of 3D-SBL at 2.0 mm coronal root length (RL) and 15% RBL corresponded to the periodontitis stage I. Premolars with a 44% of 3D-SBL at coronal 4.2-4.4 mm RL and 33% RBL accorded with the periodontitis stage II. Excluding the consideration of STA, CRR = 5:6 and 4:3 were associated with the levels at 15% and 33% RBL, respectively. CONCLUSIONS: A greater percentage of 3D-CAL than that of 2D-CAL is significant at evaluated levels. It is feasible to correlate the 3D-SBL, 3D-CAL, and STA parameters to evaluate the stages of periodontitis severity. However, the current use of RBL and CAL as applied for staging in the 2017 classification might be inconsistent with the evaluated premolar roots length, when STA dimensions are considered.

Comparison of patient's satisfaction with implant-supported mandibular overdentures and complete dentures.

BACKGROUND: The purpose of this study was to compare patients' subjective experiences with respect to long-term satisfaction with mandibular implant-retained overdentures versus conventional complete dentures. METHODS: Among 85 completely edentulous patients, 60 were treated with four one-stage titanium implants and overdentures retained by a cast bar with extracoronal attachments. These patients constituted the experimental group, and were subsequently evaluated clinically over a period of up to 6 years. The other 25 patients constituted the control group and were treated with conventional complete dentures without implant retained. All the patients (n = 60) in the experimental group responded to questions on their experiences before and after treatment with the implant-retained overdentures. Sixty percent (n = 15) of the 25 patients in the control group responded to the questionnaire. RESULTS: No implants or restorations failed during the observation period. The experimental group, however, showed significant differences with the control group in terms of their responses to the questionnaire. CONCLUSION: The use of implants to retain and support the overdenture improved comfort and gave the experimental patients greater self-confidence in social interactions, in addition to more effective oral rehabilitation. The results demonstrate that the effects of rehabilitation of the mandibular arch with an implant-retained overdenture are predictable.

Occurrence and genotype of Giardia cysts isolated from faecal samples of children and dogs and from drinking water samples in an aboriginal area of central Taiwan.

To investigate some aspects of Giardia infection, we performed a cross-sectional study on schoolchildren from an aboriginal area of Nantou County in central Taiwan. Faecal samples from 209 participants and samples of dog faeces and of water from mountain springs found in the area were collected. The participants also filled a questionnaire pertaining to demographic data. Giardia duodenalis was detected in eight of the 209 participants, and all positive isolates belonged to assemblage A. In addition, assemblage A isolates were obtained from four of the 22 water samples, and assemblage C or D isolates were obtained from four of the 42 canine faecal samples. Our results suggest that the risk of Giardia transmission is greater from waterborne than canine transmission in this study area.