Removable partial dentures assisted by short implants: A 34-month randomized controlled clinical trial.

STATEMENT OF PROBLEM: Implant-assisted removable partial dentures (IARPDs) have been used to treat partially edentulous patients, yet limited information is available on the relationship between prosthetic complications and patient satisfaction as compared with conventional removable partial dentures (RPDs). PURPOSE: The purpose of this randomized controlled clinical trial was to measure the satisfaction of patients who received either conventional or RPDs assisted by short implants and to assess and compare the incidence and type of prosthetic complications after a mean observational period of 34 months. MATERIAL AND METHODS: Thirty-one healthy and bilaterally edentulous (Kennedy Class I) individuals who were seeking treatment and were candidates for posterior implant placement, were randomly allocated to either the conventional removable partial denture (CRPD) or the short implant-assisted removable partial denture (IARPD) groups. CRPDs following the same fabrication procedures were delivered to all participants irrespective of the group assignment,. One month after delivery, each participant from the IARPD group received 2 short implants. Upon osseointegration, the existing prostheses were converted to IARPDs with the use of LOCATOR attachments. The chi-squared test, log-rank test, and Mann-Whitney U test were used for statistical analysis (α=.05). RESULTS: Data were collected from 31 participants: 18 in the CRPD and 13 in the IARPD group. The results showed that prosthetic complications occurred in both CRPD and IARPD groups. The chi-squared test showed no statistically significant difference between the 2 groups with regard to the incidence of prosthetic complications (P=.474). The log-rank test used for survival rate and complications showed no statistically significant difference between the 2 groups (P=.903). The Mann-Whitney U test showed no statistically significant difference in patient satisfaction between the 2 groups (P=.938). CONCLUSIONS: No statistically significant difference in the incidence and type of prosthetic complications was observed between conventional and RPDs assisted by short implants after a mean observation period of 34 months.

Digital denture with mucostatic base and functional borders: A cast-free digital technique.

Digital complete dentures fabricated using a mucostatic impression, like intraoral scans, are desirable for their beneficial effect on long-term residual ridge stability but may have less retention than those fabricated with a mucocompressive impression. Border molding procedure may improve initial retention, thus favoring adaptation to new dentures, especially in cases where neuromuscular dysfunctions may diminish the patient's ability to cope with adapting to existing motor patterns or learn new ones. However, a mucocompressive impression may cause higher residual ridge resorption, thus resulting in a retention decrease over time. A desirable combination would be a digital denture with a mucostatic intaglio surface obtained from intraoral scans and functional borders. A cast-free digital workflow for that is demonstrated in this technical report.

A comparison of alveolar ridge mucosa thickness in completely edentulous patients.

PURPOSE: The purpose of this cross-sectional clinical study was to determine and compare alveolar ridge mucosa thickness at crestal, buccal, and lingual locations of the maxillary and mandibular arches in completely edentulous patients using a dedicated, ultrasonic gingival scanner. MATERIALS AND METHODS: Thirty-eight completely edentulous subjects were included in the study. In each subject, soft tissue thickness was measured at 28 sites of the edentulous ridge by a single calibrated examiner. Intra-observer reliability was calculated with Intraclass Correlation Coefficients by measuring 10 subjects twice, after 1 week. Measurements (mm) were taken at the buccal, lingual, and crestal aspects of the ridge with a dedicated ultrasonic scanner. Repeated measures ANOVA and paired t-tests were used to compare the mean buccal, lingual, and crestal soft tissue thicknesses at each site. The Generalized Estimating Equations model was used to study the effects of age, sex, and race. Confidence level was set to 95%. RESULTS: Mean tissue thickness ranged from 0.96  to 1.98 mm with a mean of 1.63 ± 0.25 mm. Intraclass Correlation Coefficients were > 0.97. No significant differences between buccal, crestal, and lingual sites were noted for the mandibular arch as well as at 4 sites on the maxillary arch (maxillary right second molar, maxillary right canine, maxillary left first premolar, maxillary left second molar). However, significant differences in soft tissue thickness were noted for all remaining maxillary sites. Race was found to be positively correlated with tissue thickness, with Black individuals showing a significantly greater thickness than White individuals at 4 sites (maxillary right first molar, maxillary left canine, mandibular right second premolar, mandibular right first molar). Age was found to be positively correlated with tissue thickness at 4 sites (maxillary left central incisor, maxillary left first molar, maxillary left second molar, mandibular left second premolar) and negatively correlated at 2 sites (mandibular right canine, mandibular right second molar). Female sex was positively (maxillary left second premolar, maxillary left second molar) and negatively (mandibular right canine) correlated, respectively, with tissue thickness at 3 sites. When data for anterior and posterior sites were respectively pooled, tissue thickness was significantly less at anterior sextant lingual and crestal sites, while no difference was seen for buccal sites. CONCLUSION: Statistically significant differences for alveolar ridge mucosa thickness were found at several sites in the maxilla and between anterior and posterior sextants for lingual and crestal sites in the maxillary and mandibular arches. Tissue thickness differences were also noted for race with Black individuals showing greater tissue thickness at some sites. Age and sex did not show a clear effect on tissue thickness. Recorded differences in tissue thickness were however small and appear of uncertain clinical significance.

Interproximal contact loss between implant restorations and adjacent natural teeth: A systematic review and meta-analysis.

PURPOSE: This systematic review was conducted to evaluate the prevalence of interproximal contact loss (ICL) between implant restorations and adjacent teeth in relation to age, gender, follow-up time, and arch location. METHODS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and was registered in the Open Science Framework (OSF). The formulated population, intervention, comparison, outcome (PICO) question was "What is the prevalence of the ICL between implant restoration and adjacent teeth?" The search strategy used four main electronic databases and an additional manual search was performed until February 2023. Clinical studies that evaluated the prevalence of interproximal open contact between implant restorations and adjacent teeth were included. A qualitative analysis for clinical studies was used to assess the risk of bias. In addition, a single-arm meta-analysis of proportion was performed to evaluate the percentage of mesial versus distal open contact and total ICL between implant restoration and adjacent teeth. RESULTS: Fifteen studies published between 2014 and 2023 met the eligibility criteria. Seven studies presented ICL rates higher than 20%. All studies evaluated ICL in posterior regions (molar, premolar area). Five studies had an ICL rate lower than 50% and three studies had an ICL rate higher than 50%. One study assessed the interproximal contact at three months post-restoration insertion, four studies assessed the interproximal contact at 1-year follow-up and nine studies evaluated the interproximal contact over 2 years of follow-up. Mesial and distal ICL rates were 44.2% (95% CI: 30.6% to 58.6%) and 27.5% (95% CI: 10.5% to 55.0%), respectively. The heterogeneity between studies was high (I2 (95% CI) = 87.8% (75.9% to 93.8%). CONCLUSION: Based on the results of the included studies, the prevalence of ICL was high, occurring more frequently at the mesial contact. There were no significant differences in relation to age, gender, and arch location.

Centric relation-A biological perspective of a technical concept.

BACKGROUND: Few terms and concepts have been so extensively debated in dentistry as the words 'centric relation' (CR). Debates involve its biological, diagnostic and therapeutic usefulness. METHODS: A review of the literature on the current concepts on CR as a diagnostic or therapeutic aid in dentistry was provided. Clinical trials assessing the superiority of one CR recording method over the others to identify patients with temporomandibular disorders (diagnostic use) or to manage patients with prosthodontic or orthodontic needs (therapeutic use) were tentatively included. RESULTS: Due to the absence of literature addressing either of the above targets, a comprehensive overview was provided. The diagnostic use of CR as a reference position to identify the correct position of the temporomandibular joint condyle within the glenoid fossa is not supported and lacks anatomical support. From a therapeutic standpoint, the use of CR can be pragmatically useful in prosthodontics as a maxillo-mandibular reference position when occlusal re-organization is warranted and/or when the position of maximum intercuspation is no longer available. CONCLUSIONS: The derived occlusal goals from a diagnostic misuse of CR are generally the result of circular reasoning, that is a technique is based on the recording of a certain condylar position that is believed to be 'ideal' and the treatment is considered successful when such position is shown by the specific instrument that was manufactured for that purpose. The term 'Centric Relation' might be replaced with the term 'Maxillo-Mandibular Utility Position'.

Assessment of distortion of intraoral scans of edentulous mandibular arch made with a 2-step scanning strategy: A clinical study.

STATEMENT OF PROBLEM: Manufacturers of several intraoral scanners have recommended a 2-step strategy for scanning the edentulous mandible. The 2-step technique requires scanning one side first and then moving to the other side. However, whether inconsistency in stitching occurs that results in loss of accuracy or distortion is unclear. PURPOSE: The purpose of this clinical study was to measure the potential distortion of intraoral scans of edentulous mandibular arches made with a 2-step scanning strategy and to assess their differences with conventional impressions. MATERIAL AND METHODS: Twenty mandibular edentulous arches were scanned by 1 investigator with an intraoral scanner using a 2-step scanning strategy, and a corresponding polysulfide conventional impression was obtained. The conventional impression was then immediately scanned with the same intraoral scanner. The obtained standard tessellation language (STL) files were superimposed with a surface-matching software program. After a preliminary alignment, the STL meshes were trimmed and reoriented; then, the final alignment was carried out and meshes moved to a metrology software program where their mean distance was measured. In addition, a surface curve (SIOS) was traced on the intraoral scan from the right to left retromolar pad along the residual ridge and automatically projected onto to the conventional impression scan to obtain a new curve (SC). The mean distance between SIOS and SC was measured and recorded as an indicator of the distortion by considering the X-, Y-, and Z-axes and the overall 3-dimensional (3D) deviation. The analysis was performed for the full curve length and after dividing it into 6 regions of interest. Univariate and multivariate statistical analyses were used to investigate the significance of the extent of the mean 3D distance, as well as the effects of measurement positions (side and region) between and within patients on differences along the X-, Y-, and Z-axes (α=.05). RESULTS: The mean (-0.08 mm; standard error: 0.025) 3D distance between the intraoral scan and conventional impression was significantly different from zero (P=.003). No significant effect of the factor "side" was found by using generalized estimated equation models for the X-, Y-, and Z-axes, and global 3D deviations between SIOS and SC (P>.05), which appeared to exclude distortion. Conversely, a significant effect was found for the factor "region" (P<.05), with no significant differences (P>.05) between corresponding regions on the 2 sides. CONCLUSIONS: Intraoral scans of the edentulous mandibular arch made in a 2-step procedure did not exhibit significant distortion in comparison with conventional impressions.

Intaglio surface trueness of milled and 3D-printed digital maxillary and mandibular dentures: A clinical study.

STATEMENT OF PROBLEM: While the dimensional accuracy of the intaglio surface of a removable complete denture is key to its adaptation, comfort, and clinical performance, information on the ability of milling and 3D-printing workflows to accurately reproduce this surface is lacking. PURPOSE: The purpose of this clinical study was to compare the trueness of the intaglio surface of milled and 3D-printed removable complete digital dentures. MATERIAL AND METHODS: Intraoral scans were obtained from 14 participants for a total of 20 edentulous arches. Ten maxillary and 10 mandibular denture bases were then designed and fabricated with a completely digital workflow, both with milling and 3D-printing. Fabricated dentures were digitized with the same intraoral scanner used to obtain intraoral digital scans of the edentulous arches. Standard tessellation language (STL) files of the printed and milled denture bases were used for 3D analysis and comparisons with the STL file of the corresponding designed denture base. Specifically, a reverse engineering software program was used to trim and extract intaglio surfaces, align them, and measure their global mean 3D distance. In order to evaluate the homogeneity of production accuracy of each manufacturing process, the intaglio surfaces were also divided into several regions of interest and the corresponding 3D distances measured. Within- and between-group differences and maxillary and mandibular dentures differences were assessed with parametric and nonparametric tests (α=.05). RESULTS: Milling showed a global better trueness of the entire intaglio surface (-0.002 mm) than 3D-printing (0.018 mm), both for the whole data set (P<.001) and for maxillary (P=.032) or mandibular (P=.049) denture base subgroups. Within each fabrication technology, maxillary (P<.11) and mandibular dentures (P=.2) showed no significant difference in trueness. Measured deviations were significantly different from zero for the 3D-printed dentures (P<.001), but not for the milled dentures (P=.487). Additionally, for milled dentures, no significant difference in trueness was found among the 11 regions of interest identified for the maxillary dentures (P=.085) and the 13 regions of interest for the mandibular dentures (P=.211). Conversely, 3D-printing showed significant variations in trueness among the same zones of interest, both in maxillary (P<.001) and mandibular (P=.004) dentures. CONCLUSIONS: Within the limits of the manufacturing methodologies used for complete dentures, milling can provide a slightly better trueness of the intaglio surface than 3D-printing, with less variation across several zones of interest. However, given the magnitude of such differences, they may be reasonably considered to be of limited, if any, clinical significance.

Three Dimensional Printed Surgical Guides: Effect of Time on Dimensional Stability.

PURPOSE: To analyze, in vitro, the dimensional stability over time of 3D-printed surgical guides. MATERIALS AND METHODS: Ten surgical guides, manufactured by digital light processing 3D-printing technology, were scanned immediately after post-processing and then after 5, 10, 15, and 20 days. The corresponding standard tessellation language (STL) files were used for comparison with the reference CAD project. Mean absolute deviation (MAD) of the intaglio surface, axial, and linear deviations of the sleeves' housings were measured. Generalized estimated equations models (α = 0.05) were used to investigate the effect of time. RESULTS: MAD of the teeth intaglio surface showed less variation (minimum: 0.002, maximum: 0.014 mm) than that of the mucosa (minimum: 0.026, maximum: 0.074 mm). Axial variations of the sleeves' housings on the sagittal (minimum: -0.008°, maximum: -0.577°) and frontal plane (minimum: -0.193°, maximum: 0.525°) changed with similar patterns, but opposite trends (decreasing for the former). Linear deviations of center points of the sleeves' housings had a shifting (minimum: -0.074, maximum: 0.02 mm) pattern with a decreasing tendency. Time after processing had a significant effect, either alone or nested with guides volume, on all outcomes of interest, except for MAD of the mucosa intaglio surface (p < 0.001), which was significantly affected only by the time-volume nested effect (p = 0.012). CONCLUSIONS: Within the limitations of the experimental design, postmanufacturing dimensional variations of surgical guides were statistically significant. Although limited, they are an additional source of variability affecting the overall accuracy of computer-guided surgery. As such, they should be addressed by further research.

Effect of implant angulation and patrice on the retention of overdenture attachment systems: An in vitro study.

PURPOSE: To test the retention of two different overdenture attachment matrices and straight abutments when implants are placed at 0-, 15-, and 30-degree diverging angulations as well as the retention of 15-degree-angled abutments to correct the overall angulation to 0-degrees. MATERIALS AND METHODS: Matching aluminum blocks were machined to incorporate two dental implants at 0-degree, 15-degree, and 30-degree relative angulations and overdenture attachments to simulate a two-implant overdenture. At 0-degree, 15-degree, and 30-degree implant angulation, straight abutments were studied. At 30-degree implant angulation, an additional group was compared utilizing 15-degree angulated abutments that corrected the overall implant angulation to 0-degrees. A custom-designed testing apparatus that allowed automated insertion and removal of the simulated overdenture was designed, with three independent testing stations, each consisting of one simulated arch and one simulated overdenture base. The baseline and residual retention forces after 30,000 dislodging cycles of the simulated overdenture were measured. One-way ANOVA was used to compare retention differences among different color patrices within the 0-, 15-, and 30-degree implant angulation groups followed by Tukey's multiple comparison test. Two sample t-tests were used to compare 0-degree versus 15-degree implant groups with straight abutments and 30-degree implant groups with straight abutments versus 30-degree implant groups with angulated abutments. RESULTS: Regardless of implant angulation or abutment correction, the change in retention exhibited by the Novaloc system after testing was not statistically significant for all patrice types (p > 0.05); however, the change in retention exhibited by the Locator system was statistically significant for the tested group (p = 0.0272). In both the Novaloc and Locator systems, the baseline and final retention values provided by the different patrices were significantly different except for the white and green Novaloc patrices in the 15-degree divergent implant group which did not meet the specified level of significance (p = 0.0776). CONCLUSION: Within the limitations of this study, implant angulations upto 15 degrees do not affect differential change in retention of Novaloc patrices. There is no difference between Novaloc white inserts (light retention value) and green inserts (strong retention values) when implants diverge upto 15 degrees. When Novaloc straight abutments were placed on implants diverging by 30 degrees, blue extra-strong retention inserts outperformed yellow medium retention inserts by maintaining a higher retention value after 30,000 cycles. When utilizing Novaloc 15-degree angulated abutments that correct the overall implant angulation to zero degrees, the red light retentive patrice provides steady retention. Finally, the Locator-green patrice system provides greater retention than the comparable Novaloc-blue patrice combination; however, it also loses more retention after 30,000 cycles.

Insertion and removal torque of dental implants placed using different drilling protocols: An experimental study on artificial bone substitutes.

PURPOSE: The aim of this in vitro study was to measure the insertion and removal torque values of dental implant replicas inserted into artificial bone blocks using different surgical burs and drilling protocols. MATERIALS AND METHODS: Four types of artificial, polyurethane bone blocks were used with different thicknesses (1 and 2 mm) and densities (soft-1 mm, soft-2 mm, dense-1 mm, and dense-2 mm) of the simulated cortical and cancellous bone, respectively. Each bone construct was drilled with Straumann and Densah drills in both clockwise and counterclockwise directions for a total of 16 experimental conditions. For every scenario, 38 implant replicas were inserted and then removed after 1 min. Outcomes of interest were the insertion and removal torque values which were recorded by a torque meter. ANOVA and Tukey HSD tests were used to assess differences across each combination of drill, direction, and bone type. RESULTS: Densah counterclockwise registered statistically greater values for both insertion and removal torque, followed by Densah clockwise, Straumann counterclockwise, and Straumann clockwise. Increasing insertion and removal torque values were progressively reported for bone type (soft-1 mm, dense-1 mm, soft-2 mm, and dense-2 mm). The mean values of insertion and removal torque were significantly different (p < 0.05) across the four bone types, different burs, and with the two drilling modalities. CONCLUSIONS: Densah bur resulted in significantly greater values of torque compared to the Straumann drills for all the experimental conditions. The thickness of the cortical layer and the counterclockwise drilling direction play a significant role in determining the implant insertion torque.

Survival rates, patient satisfaction, and prosthetic complications of implant fixed complete dental prostheses: a 12-month prospective study.

PURPOSE: To determine the survival rate, incidence of prosthetic complications, and patient satisfaction of implant fixed complete dental prostheses (IFCDPs) after a mean observation period of 1.4 years. MATERIALS AND METHODS: Twenty-eight (28) eligible participants were recruited according to specific inclusion and exclusion criteria. The definitive metal-acrylic resin IFCDPs consisted of titanium bars veneered with acrylic resin and acrylic denture teeth. Prosthodontic complications, divided into major and minor, were monitored. Parameters such as gender, jaw location, bruxism, and occlusal scheme were evaluated. Moreover, a questionnaire was administered throughout the study to assess patient satisfaction. Poisson regression as well as repeated measures ANOVA were used for statistical analysis. RESULTS: Fourteen (14) males and 14 females were enrolled and followed-up at 3, 6, and 12 months. All IFCDPs survived (100% survival rate). The most frequent minor complication was the loss of material used to close the screw access hole (20% out of total complications). The most frequent major complication was chipping of the acrylic denture teeth (77.14% out of total complications). Gender (p = 0.008) and bruxism (p = 0.030) were significant predictors for the total major complications (major wear and major chipping) while occlusal scheme was a significant predictor for major chipping events (p = 0.030). CONCLUSIONS: While IFCDPs demonstrated high prosthetic survival rates, they also exhibited a high number of chipping events of the acrylic veneering material, especially in males, bruxers, and individuals with canine guidance occlusion. However, the occurrence of these prosthetic complications did not negatively affect patient satisfaction.

Evaluation of marginal and internal fit of single crowns manufactured with an analog workflow and three CAD-CAM systems: A prospective clinical study.

PURPOSE: This prospective clinical study evaluated and compared the marginal and internal fit of crowns fabricated with an analog workflow and three different computer-aided design and computer-aided manufacturing (CAD-CAM) systems. MATERIALS AND METHODS: Twenty-five participants in need of a single complete-coverage molar or premolar crown were recruited in the study. Twenty-two completed the study, and three participants dropped out. Teeth were prepared according to a standardized protocol by one operator. For each participant, one final impression was made with polyether material (PP) and three intraoral scanners: CEREC Omnicam (C), Planmeca Planscan (PM), and True Definition (TR). For the PP group, crowns were fabricated with a pressable lithium disilicate ceramic, whereas for the other three groups (C, PM, and TR), crowns were designed and milled with dedicated CAD-CAM systems and materials. Marginal (vertical and horizontal) and internal discrepancies between the crowns and tooth preparation were measured at various locations with digital superimposition software. Data was analyzed for normality with Kolmogorov-Smirnov and Shapiro-Wilk tests and then compared with one-way ANOVA and Kruskal-Wallis tests. RESULTS: Mean vertical marginal gap values were 92.18 ± 141.41 µm (PP), 150.12 ± 138.06 µm (C), 129.07 ± 109.96 µm (PM), and 135.09 ± 112.03 µm (TR). PP group had statistically significantly smaller vertical marginal discrepancy (p = 0.001) than all other groups, whereas no significant difference was detected among the three CAD-CAM systems (C, PM, and TR). Horizontal marginal discrepancies were 104.93 ± 111.96 µm (PP), 89.49 ± 119.66 µm (C), 113.36 ± 128.49 µm (PM), and 136.39 ± 142.52 µm (TR). A significant difference was detected only between C and TR (p < 0.0001). Values for the internal fit were 128.40 ± 49.31µm (PP), 190.70 ± 69.79µm (C), 146.30 ± 57.70 µm (PM), and 168.20 ± 86.67 µm (TR). The PP group had a statistically significant smaller internal discrepancy than C (p < 0.0001) and TR groups (p = 0.001), whereas no significant difference was found compared to the PM group. CONCLUSION: Posterior crowns fabricated with CAD-CAM systems showed vertical margin discrepancy greater than 120 µm. Only crowns fabricated with the conventional methodology had vertical margins below 100 µm. Horizontal marginal discrepancy was different among all groups, and only CEREC CAD-CAM was below 100 µm. Internal discrepancy was less for crowns fabricated with an analog workflow.

Comparative cost-analysis for removable complete dentures fabricated with conventional, partial, and complete digital workflows.

STATEMENT OF PROBLEM: Comparative cost-analysis related to different manufacturing workflows for removable complete denture fabrication is seldom performed before the adoption of a new technology. PURPOSE: The purpose of this study was to compare the clinical and laboratory costs of removable complete dentures fabricated with a conventional (workflow C), a partial digital (workflow M), and a complete digital (workflow D) workflow and to calculate the break-even points for the implementation of digital technologies in complete denture fabrication. MATERIAL AND METHODS: Clinical and laboratory costs for each of the investigated workflows and the manufacturing options related to denture base and denture teeth fabrication were collected from 10 private Italian dental laboratories and clinics. The selected variables included the clinical and laboratory manufacturing time needed to complete each workflow (opportunity cost); costs for materials, labor, packaging, and shipping; and capital and fixed costs for software and hardware, including maintenance fees. The effect of manufacturing workflows and their options on the outcomes of interest was investigated by using generalized estimated equations models (α=.05). Cost minimization and sensitivity analysis were also performed, and break-even points were calculated for the equipment capital costs related to the implementation of workflows M and D. RESULTS: From a laboratory standpoint, workflows M and D and related manufacturing options significantly (P<.001) reduced manufacturing time (5.90 to 6.95 hours and 6.30 to 7.35 hours, respectively), and therefore the opportunity cost of each denture compared with workflow C. Workflow M allowed variable costs savings between 81 and 169 USD, while workflow D allowed for an additional saving of 34 USD. The sensitivity analysis showed that the break-even point related to the capital investment for the equipment needed to implement workflows M and D could be reached, depending on the manufacturing options adopted, between 170 and 933 dentures for workflow M and between 73 and 534 dentures for workflow D. From a clinical standpoint, workflows C and M were almost identical. Conversely, workflow D, which included intraoral scanning, required 1 fewer appointment, saving 0.6 hours of chairside time and about 14 USD for materials compared with M. CONCLUSIONS: Digital workflows (partial and complete digital workflows) were more efficient and cost-effective than the conventional method of fabricating removable complete dentures, with workflow D showing the lowest opportunity and variable costs and break-even point. Savings increased when stock denture teeth were replaced with milled denture teeth and still further with the adoption of 3-dimensionally (3D) printed denture teeth. Milling equipment and materials for denture base fabrication were more expensive than those for 3D-printing. Milling monobloc dentures reduced opportunity and labor costs but increased material cost.

Implant survival and biologic complications of implant fixed complete dental prostheses: An up to 5-year retrospective study.

STATEMENT OF PROBLEM: Limited information is available on the association between prosthesis-associated risk factors and biologic complications for patients with implant fixed complete dental prostheses (IFCDPs). PURPOSE: The purpose of this retrospective study was to assess the implant survival and biologic complications of IFCDPs up to 5 years of follow-up. MATERIAL AND METHODS: Patients who had received IFCDPs between August 1, 2009 and August 1, 2014 were identified through an electronic health record review. Those who consented to participate in the study attended a single-visit study appointment. Clinical and radiographic examinations, intraoral photographs, and peri-implant hard and soft tissues parameters were assessed. Only prostheses which could be removed during the study visit were included. Associations between biologic complications and prosthetic factors, such as time with prosthesis in place, prosthesis material, number of implants, cantilever length, and type of prosthesis retention, were assessed. RESULTS: A total of 37 participants (mean ±standard deviation age 62.35 ±10.39 years) with 43 IFCDPs were included. None of the implants had failed, leading to an implant survival of 100% at 5.1 ±2.21 years. Ten of the prostheses were metal-ceramic (Group MC) and 33 were metal-acrylic resin (Group MR). Minor complications were more frequent than major ones. Considering minor complications, peri-implant mucositis was found in 53% of the implant sites, more often in the maxilla (P=.001). The most common major biologic complication was peri-implantitis, which affected 4.0% of the implants, more often in the mandible (P=.025). Peri-implant soft tissue hypertrophy was present 2.79 times more often (95% CI: 1.35 - 5.76, P<.003) around implants supporting metal-acrylic resin prostheses than metal-ceramic ones, with the former type also showing significantly more plaque accumulation (P<.003). CONCLUSIONS: Biologic complications such as soft tissue hypertrophy and plaque accumulation were more often associated with metal-acrylic resin prostheses. Peri-implant mucositis occurred more often under maxillary IFCDPs, while peri-implantitis appeared more common around mandibular implants.

Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae.

PURPOSE: To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow. MATERIALS AND METHODS: Sixteen patients received intraoral full-arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer-aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer-aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw-resistance test and direct observation. RESULTS: Out of the 16 digitally fabricated prototypes from intraoral full-arch digital scans, all 16 presented with an accurate fit on verified master stone casts. CONCLUSIONS: Digitally fabricated full-arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.

Esthetic and Functional Rehabilitation of an Adolescent Patient with Severe Dental Fluorosis: A Clinical Report.

Dental fluorosis is a developmental defect affecting amelogenesis. It presents clinically in different forms depending on the concentration, duration, and time of exposure to fluoride. Several therapeutic modalities have been described to manage mild and moderate forms of dental fluorosis; however, limited literature is available on the restorative management of severe forms of dental fluorosis, specifically in young individuals. This clinical report describes a complete prosthodontic rehabilitation of an adolescent patient with severe dental fluorosis affecting his permanent dentition. The patient was treated with a combination of monolithic, minimally-veneered zirconia crowns and direct composite resins. At the 1-year follow-up appointment, there were no complications, and both the patient's oral health and the integrity of the restorations remained stable.

Titanium Nitride Coated Implant Abutments: From Technical Aspects And Soft tissue Biocompatibility to Clinical Applications. A Literature Review.

PURPOSE: To review the most up to date scientific evidence concerning the technical implications, soft tissue biocompatibility, and clinical applications derived from the use of titanium nitride hard thin film coatings on titanium alloy implant abutments. MATERIALS AND METHODS: A review was performed to answer the following focused question: "What is the clinical reliability of nitride coated titanium alloy abutments?". A MEDLINE search between 1980 and 2021 was performed for investigations pertaining to the clinical use of nitride coated titanium alloy implant abutments (TiN) in case reports, case series, and short- and long-term non/randomized controlled clinical trials. Literature analysis led to addition evaluation of research related to the technical and biological aspects, as well as the physicochemical characteristics of TiN hard thin film coatings and their impact on titanium abutment biocompatibility, mechanical properties, macroscopic surface topography, and optical properties. Therefore, preclinical data from biomechanical and in vitro investigations were also considered as inclusion criteria. RESULTS: The limited number of clinical investigations published made a systematic review and meta-analysis not possible, therefore a narrative review was conducted. TiN coatings have been applied to dental materials and instruments to improve their clinical longevity. Implant abutments are coated with titanium nitride to mask the titanium oxide surface and enhance its surface characteristics providing the TiN abutment surface with a low friction coefficient and a very high chemical inertness. TiN coating is suggested to reduce early bacterial colonization and biofilm formation and enhance fibroblast cell proliferation, attachment and adhesion when compared to Ti controls. Additionally, studies indicate that hard thin film coatings enhance the mechanical properties (hardness and wear resistance) of titanium alloy and appears as a yellow color when deposited on the titanium alloy substrate. To date, clinical investigations show that nitride coated titanium abutments provide promising short-term clinical outcomes. CONCLUSIONS: Published research on nitride-coated abutments is still limited, however, the available biomedical research, mechanical engineering tests, in vitro investigations, and short-term clinical trials have, to date, reported promising mechanical, biological, and esthetic outcomes.

Removable Partial Dentures with Polyetheretherketone Framework: The Influence on Residual Ridge Stability.

PURPOSE: To provide, in a clinical case-control study, 1-year data on edentulous residual ridge dimensional changes for patients wearing removable partial dentures (RPD) with Polyetheretherketone (PEEK) framework, fabricated with a digital workflow, and a control group of untreated patients. MATERIALS AND METHODS: Ten patients were treated with PEEK RPD, and six controls were studied. Intraoral scans at baseline (T0) and after a median period of 1 year (T1) were superimposed, trimmed, and reoriented (T0r and T1r), moved to a metrology software, and realigned. A curve (C0) was then traced on T0r, along the residual ridge crest; its projection (C1) on T1r was obtained. The mean distance C0-C1 was the dependent variable of interest and represented the 1-year changes in the height of the edentulous ridge. In addition, mean 3D distance between T0 and T1 at each edentulous area was measured. Differences in these outcomes measured between RPD treated and control groups were statistically assessed. RESULTS: Twenty-six and 14 edentulous areas were investigated in the RPD treated and control groups, respectively. No significant differences were observed for potentially confounding variables, such as median follow-up time (12.5 vs. 13 months, respectively), the alignment accuracy between T0r and T1r (0.01 mm vs. 0 mm, respectively), the median number of remaining teeth (6 vs. 8.5, respectively), and the median length of edentulous areas (25.5 mm vs. 22.8 mm, respectively). For the outcomes of interest, no statistically significant difference was seen in the mean distance between C0 and C1 (i.e., changes in residual ridge height: -0.39 ± 0.52 mm vs. -0.52 ± 0.54 mm, respectively) or in the mean 3D distance at corresponding points of the denture bearing areas (-0.3 ± 0.46 mm vs. -0.4 ± 0.35, respectively). CONCLUSIONS: Although 1 year is a relatively short observation period, this clinical study shows that there are no short-term differences in edentulous residual ridge height and overall dimensions between patients wearing PEEK RPD, fabricated with a digital workflow, and controls without an RPD.

Clinical Evaluation of Pink Esthetic Score of Immediately Impressed Posterior Dental Implants.

PURPOSE: While comparative outcome results for peri-implant crestal bone levels, mucosal margin position, and peri-implant indices have been reported, no studies are available that evaluate and compare the esthetic result of impressions performed immediately at implant placement with that of impressions performed on healed implants. The purpose of this cross-sectional study was to evaluate the pink esthetic score of posterior implants restored with an immediate impression workflow compared to implants restored with a delayed impression workflow. MATERIAL AND METHODS: Twenty-eight eligible participants who had received a single implant crown either in the premolar or molar regions at least 4 months before the study, were identified by an electronic health record review and scheduled for a single-visit study appointment. Esthetic outcomes were measured using the pink esthetic score. Several local- and prosthesis-related factors were recorded and their association with the selected outcome was assessed. Two-sample t-test was used for comparisons between the groups. RESULTS: Pink esthetic score ranged between 4 and 12 (mean: 8). No significant difference between immediate (8.36 ±1.12) and delayed (7.76 ±2.14) impression workflow groups were seen for the total PES (p = 0.25). In addition, individual comparisons between immediately and delayed impressed implants for mesial papilla (1.27 ±0.47; 0.88 ±0.78), distal papilla (0.73 ±0.65; 0.76 ±0.83), tissue margin (1.73 ±0.47; 1.47 ±0.51), tissue contour (1.27 ±0.65; 0.82 ±0.64), alveolar process (0.82 ±0.60; 1.00 ±0.87), color (1.27 ±0.65; 1.29 ±0.69), and texture (1.36 ±0.50; 1.53 ±0.62) did not show significant differences. CONCLUSIONS: The current study suggests that the pink esthetic score is not significantly different between single posterior implants impressed with immediate and delayed implant workflows.

A combined analog and digital workflow for retrofitting a monolithic ceramic crown to an existing removable partial denture.

A clinical and laboratory workflow for fabricating and retrofitting a monolithic ceramic crown to an existing removable partial denture (RPD) is described. A conventional polyvinyl siloxane impression was made of the prepared tooth with the RPD in place. A stone cast was poured and, after die sectioning, scanned with a tabletop scanner. The ceramic crown was designed and fabricated by using a digital workflow to fit the RPD clasp assembly, providing an adequate undercut for the clasp. The crown was then delivered and the RPD evaluated for adequate fit.