3D printing vs traditional workflow for the fabrication of mandibular implant overdentures: study protocol for a mixed-methods cross-over RCT.

BACKGROUND: Complete tooth loss is a significant global oral health issue, particularly impacting older individuals with lower socioeconomic status. Computer-assisted technologies enhance oral healthcare access by the elderly. Despite promising in vitro reports on digital denture materials, evidence from randomized clinical trials (RCTs) is lacking to verify their performance. This cross-over RCT will investigate whether 3D-printed implant-retained mandibular overdentures (IMO) are more satisfactory for edentulous seniors than those made through traditional methods. METHODS/DESIGN: We will recruit 26 completely edentulous participants (any sex/gender) based on the following eligibility criteria: age ≥ 60 years, no tooth extraction in the past 12 months, two implants in the lower jaw, and need for new dentures in both jaws. Each participant will receive two denture pairs, either manufactured by 3D printing or traditionally, to be worn in a random order. A timeline of 3 months with each denture pair will be considered for outcome assessment (total: 6 months). Patient satisfaction with dentures will be measured by the McGill Denture Satisfaction Questionnaire. We will evaluate other patient-reported outcomes (including oral health-related quality of life) as well as clinician-assessed quality and cost. At the end of the trial, participants will choose which denture pair they wish to keep and interviewed about their experiences with the 3D-printed IMO. The quantitative and qualitative data will be incorporated through an explanatory mixed-methods strategy. A final quantitative assessment will happen after 12 months with the preferred IMO to assess the long-term performance and maintenance needs. DISCUSSION: This mixed-methods RCT will explore patient experiences with 3D-printed IMOs, aiming to assess the potential for altering clinical practice and dental public health policies. Our results will inform policies by showing whether 3D printing offers comparable outcomes at lower costs, facilitating greater access to oral care for the elderly. TRIAL REGISTRATION: ClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. https://classic. CLINICALTRIALS: gov/ct2/show/NCT06155630.

Can patients detect peri­implant mucosal inflammation? Results from a multicentre randomized trial.

PURPOSE: The objective of this study was to compare patient-reported outcomes (PROs) of peri­implant soft tissue inflammation and aesthetics around single-tooth implants in the anterior maxillary region with three different implant-abutment interface designs. METHODS: Participants were randomized to one of three different types of implant-abutment interface designs [Conical (CI), flat-to-flat (FI), and Platform Switched (PS)]. Implants and provisional crowns with prefabricated titanium abutments were placed 5 months following extraction and/or ridge augmentation. Permanent ceramic crowns with zirconia abutments were placed after 12 weeks. To assess PROs, appearance and inflammation questionnaires were completed from provisional crown placement to the 3-year follow-up. RESULTS: Tooth appearance at the 3-year follow-up revealed a difference amongst CI, FI and PS implants (p=0.049; Kruskal-Wallis test). PS was rated better than FI (p=0.047) at 1 year for appearance of soft-tissue and satisfaction with colour. There were no differences for self-consciousness, smile and pain/discomfort while eating/hard food items. CONCLUSIONS: Although participants tended to rate the health of mucosa around PS implants as slighty better than the other two implant systems, the differences were minimal and inconsistent. Thus, patient satisfaction in terms self-perceived gingival health and esthetics was high for all 3 systems tested, suggesting that patients are unable to detect mucosal inflammation. CLINICAL SIGNIFICANCE: Patients find it difficult to perceive mucosal inflammation; hence, it is recommended that patients attend implant follow-up visits, even if they do not perceive inflammation. The study suggests that there is a relationship between the PROs and the clinical outcomes of tested implants.

Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial.

BACKGROUND: Overdentures retained by a single implant in the midline have arisen as a minimal implant treatment for edentulous mandibles. The success of this treatment depends on the performance of a single stud attachment that is susceptible to wear-related retention loss. Recently developed biomaterials used in attachments may result in better performance of the overdentures, offering minimal retention loss and greater patient satisfaction. These biomaterials include resistant polymeric matrixes and amorphous diamond-like carbon applied on metallic components. The objective of this explanatory mixed-methods study is to compare Novaloc, a novel attachment system with such characteristics, to a traditional alternative for single implants in the mandible of edentate elderly patients. METHODS/DESIGN: We will carry out a randomized cross-over clinical trial comparing Novaloc attachments to Locators for single-implant mandibular overdentures in edentate elderly individuals. Participants will be followed for three months with each attachment type; patient-based, clinical, and economic outcomes will be gathered. A sample of 26 participants is estimated to be required to detect clinically relevant differences in terms of the primary outcome (patient ratings of general satisfaction). Participants will choose which attachment they wish to keep, then be interviewed about their experiences and preferences with a single implant prosthesis and with the two attachments. Data from the quantitative and qualitative assessments will be integrated through a mixed-methods explanatory strategy. A last quantitative assessment will take place after 12 months with the preferred attachment; this latter assessment will enable measurement of the attachments' long-term wear and maintenance requirements. DISCUSSION: Our results will lead to evidence-based recommendations regarding these systems, guiding providers and patients when making decisions on which attachment systems and implant numbers will be most appropriate for individual cases. The recommendation of a specific attachment for elderly edentulous patients may combine positive outcomes from patient perspectives with low cost, good maintenance, and minimal invasiveness. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03126942 . Registered on 13 April 2017.

Lay preferences for dentogingival esthetic parameters: A systematic review.

STATEMENT OF PROBLEM: An objective definition of the characteristics that render a smile esthetically acceptable in the eye of laypeople is lacking. PURPOSE: The purpose of this systematic review was to identify, appraise, and synthesize the available evidence on the opinion of laypeople regarding the dentogingival characteristics that render a smile esthetically acceptable. The evidence was collected by surveying with standardized digitally modified smile images. MATERIAL AND METHODS: Four databases were used to search English language studies published between January 1996 and December 2015. This was complemented by a manual search of 8 dental journals. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, 2 independent reviewers extracted the relevant characteristics of lay evaluators, the images evaluated, and the outcomes measure. Included studies were assessed in agreement with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement. Outcomes were treated as a continuous variable, and when more than 1 article provided information on a parameter, the weighted arithmetic mean was calculated. RESULTS: After 8851 articles were screened, 20 studies were included. Those studies addressed 20 different dentogingival esthetic parameters. The total number of participants interviewed was 3107. According to the Olmos classification, 6 studies had a high level of quality, and 14 studies had a moderate level of quality. The 2 reviewers agreed on all the quality assessments. In the articles reviewed, central incisors clearly played a key role in smile esthetics. Almost all dental, gingival, and occlusal parameters are related to the proportion, shape, and position of central incisors and their relation to the adjacent dental structures. CONCLUSIONS: The present review provides the estimated thresholds of tolerability and ideal values of smile parameters determined by laypeople. This may guide clinicians in evidence-based diagnosis and the planning of dental esthetic treatments.

Proton Pump Inhibitors and the Risk of Osseointegrated Dental Implant Failure: A Cohort Study.

Proton pump inhibitors (PPIs) have a negative impact on bone accrual. Because osseointegration is influenced by bone metabolism, this study investigates the association between PPIs and the risk of osseointegrated implant failure. This retrospective cohort study included a total of 1,773 osseointegrated dental implants in 799 patients (133 implants in 58 PPIs users and 1,640 in 741 non-users) who were treated at the East Coast Oral Surgery Clinic in Moncton, Canada, from January 2007 to September 2015. Kaplan-Meier estimator was used to describe the hazard function of dental implant failure by PPIs usage. Multilevel mixed effects parametric survival analyses were used to test the association between PPIs exposure and risk of implant failure adjusting for potential confounders. The failure rates were 6.8% for people using PPIs compared to 3.2% for non-users. Subjects using PPIs had a higher risk of dental implant failure (HR = 2.73; 95% CI = 1.10-6.78) compared to those who did not use the drugs. The findings suggest that treatment with PPIs may be associated with an increased risk of osseointegrated dental implant failure.

Failure rate of single-unit restorations on posterior vital teeth: A systematic review.

STATEMENT OF PROBLEM: No knowledge synthesis exists concerning when to use a direct restoration versus a complete-coverage indirect restoration in posterior vital teeth. PURPOSE: The purpose of this systematic review was to identify the failure rate of conventional single-unit tooth-supported restorations in posterior permanent vital teeth as a function of remaining tooth structure. MATERIAL AND METHODS: Four databases were searched electronically, and 8 selected journals were searched manually up to February 2015. Clinical studies of tooth-supported single-unit restorative treatments with a mean follow-up period of at least 3 years were selected. The outcome measured was the restorations' clinical or radiological failure. Following the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines, the Cochrane Collaboration procedures for randomized control trials, the Strengthening the Reporting of Observational Studies in Epidemiology criteria for observational studies, 2 reviewers independently applied eligibility criteria, extracted data, and assessed the quality of the evidence of the included studies using the American Association of Critical Care Nurses' system. The weighted-mean group 5-year failure rates of the restorations were reported according to the type of treatment and remaining tooth structure. A metaregression model was used to assess the correlation between the number of remaining tooth walls and the weighted-mean 5-year failure rates. RESULTS: Five randomized controlled trials and 9 observational studies were included and their quality ranged from low to moderate. These studies included a total of 358 crowns, 4804 composite resins, and 303582 amalgams. Data obtained from the randomized controlled trials showed that, regardless of the amount of remaining tooth structure, amalgams presented better outcomes than composite resins. Furthermore, in teeth with fewer than 2 remaining walls, high-quality observational studies demonstrated that crowns were better than amalgams. A clear inverse correlation was found between the amount of remaining tooth structure and restoration failure. CONCLUSIONS: Insufficient high-quality data are available to support one restorative treatment or material over another for the restoration of vital posterior teeth. However, the current evidence suggests that the failure rates of treatments may depend on the amount of remaining tooth structure and types of treatment.

Antihypertensive Medications and the Survival Rate of Osseointegrated Dental Implants: A Cohort Study.

PURPOSE: Antihypertensive drugs in general are beneficial for bone formation and remodeling, and are associated with lower risk of bone fractures. As osseointegration is influenced by bone metabolism, this study aimed to investigate the association between antihypertensive drugs and the survival rate of osseointegrated implants. MATERIALS AND METHODS: This retrospective cohort study included a total of 1,499 dental implants in 728 patients (327 implants in 142 antihypertensive-drugs-users and 1,172 in 586 nonusers). Multilevel mixed effects parametric survival analyses were used to test the association between antihypertensive drugs use and implant failure adjusting for potential confounders. RESULTS: Only 0.6% of the implants failed in patients using antihypertensive drugs while 4.1% failed in nonusers. A higher survival rate of dental implants was observed among users of antihypertensive drugs [HR (95% CI): 0.12 (0.03-0.49)] compared to nonusers. CONCLUSIONS: Our findings suggest that treatment with antihypertensive drugs may be associated with an increased survival rate of osseointegrated implants. To our knowledge, this could be the first study showing that the systemic use of a medication could be associated with higher survival rate of dental implants.

A multicenter randomized comparative trial of implants with different abutment interfaces to replace anterior maxillary single teeth.

PURPOSE: The implant-abutment interface may affect peri-implant mucosal architecture, and influence health and esthetics. The goal of this 1-year follow-up report of a 5-year clinical investigation was to examine the peri-implant mucosal tissue responses to different implant-abutment interface designs. MATERIALS AND METHODS: Subjects requiring an anterior maxillary implant were recruited. Tooth extractions, with or without preservation or ridge augmentation procedures, were performed as required. After 5 months of healing, one of three different implant-abutment combinations (conical interface [CI] n = 48); flat-to-flat interface [FI] n = 49); or platform switch interface [PS] n = 44) was placed and provisionalized. Twelve weeks later, permanent crowns were placed and data gathered throughout the first year. Peri-implant mucosal architecture and bone levels were evaluated clinically, photographically, and radiographically. RESULTS: At 1 year, seven FI and six PS implants failed and two FI and two PS implant participants were lost to follow-up, resulting in survival rates of 100% (CI), 85.7% (FI), and 86.4% (PS) (90.8% overall). Marginal bone level changes were -0.22 mm (CI, P < .05), -1.2 mm (FI, P < .05), and -1.32 mm (PS, P < .05) after 1 year. Marginal bone level stability (≤ 0.5-mm bone loss or gain) was recorded for 87% (CI), 8% (FI), and 27% (PS) of implants. Measurement of midbuccal mucosal zenith and papilla positions revealed no change in the mucosal positions and 0.2 to 0.3 mm of gain in papilla dimensions in all groups. CONCLUSION: Significant differences in marginal bone loss were observed among the three implant-abutment interfaces. At 1 year follow-up, changes in the buccal mucosal zenith position or papilla dimensions were not discernable. A continued longitudinal evaluation of peri-implant bone and mucosal changes around these different interfaces is ongoing.

Impact of a "TED-Style" presentation on potential patients' willingness to accept dental implant therapy: a one-group, pre-test post-test study.

PURPOSE: A survey was conducted to assess the impact of a TED-like educational session on participants' willingness to accept dental implant therapy. MATERIALS AND METHODS: Volunteers interested in having information about dental implant therapies were recruited and asked to complete a two-part survey before and after an educational session. The initial survey elicited demographic information, self-perceived knowledge on dental implants and willingness to this kind of treatment. A "TED-style" presentation that provided information about dental implant treatments was conducted before asking the participants to complete a second set of questions assessing the impact of the session. RESULTS: The survey was completed by 104 individuals, 78.8% were women and the mean age was 66.5±10.8. Before the educational session, 76.0% of the participants refused dental implants mainly due to lack of knowledge. After the educational session, the rejection of dental implants decreased by almost four folds to 20.2%. CONCLUSION: This study proved that an educational intervention can significantly increase willingness to accept treatment with dental implants in a segment of the population who is interested in having information about dental implant therapy. Furthermore, educational interventions, such as TED-like talks, might be useful to increase popular awareness on dental implant therapy.

Plaque Accumulation Beneath Maxillary All-on-4™ Implant-Supported Prostheses.

BACKGROUND: Maxillary prostheses supported by four implants, following the All-on-4(™) principles, have become an accepted effective treatment for totally edentulous patients. Maintaining the hygiene of such fixed implant-supported prostheses is challenging. PURPOSE: The purpose of this clinical study was to evaluate the distribution of plaque on the fitting surface of All-on-4 fixed prostheses in order to find new strategies for maintaining their hygiene. MATERIALS AND METHODS: Twenty All-on-4 maxillary fixed prostheses collected from 20 patients, 6 months after delivery, were stained with methylene blue to disclose plaque accumulation at the fitting surfaces of the prostheses. Digital photographs of the fitting surfaces of the prostheses were recorded and processed. The distribution of accumulated plaque was evaluated statistically. RESULTS: The average percentage of area covered with plaque was 28 ± 8% of the total area of the fitting surface of the prostheses. The fitting surfaces of the prostheses had three times more plaque on the palatal area (52.5 ± 7.33%) than on the buccal area (17.3 ± 7.33%, p < .05). The interimplant proximal areas of the fitting surface covered with plaque were high when the distance between implants was short (r = -0.326, p = .014). CONCLUSION: These findings suggest that the hygiene of the All-on-4 prostheses could be improved by maximizing the distances between the inserted implants in the jaw, minimizing the prostheses' palatal extension and guiding patients to optimize their oral hygiene practices targeting the palatal area of their prostheses.

Effect of implant angulation on attachment retention in mandibular two-implant overdentures: a clinical study.

PURPOSE: Attachment wear can affect the performance of mandibular two-implant overdentures (IODs). This prospective clinical study aimed to investigate the effect of interimplant angulation on the retention achieved by two attachment systems at different time points within 1 year of wearing IODs. MATERIALS AND METHODS: Twenty-four patients (mean age = 73.2 years; standard deviation (SD) = 3.1) wearing IODs opposed by conventional maxillary complete dentures were randomly assigned to two groups in two-by-two crossover design. Retentive Anchor (RA) and Locator (LA) were installed in the IODs of both groups for 1 year, sequentially. Coronal and sagittal interimplant angulation were measured on posterior-anterior and lateral cephalometric radiographs. Retention was measured at baseline, 1 week, 3, 6, and 12 months postattachment installation. Data were analyzed using mixed models with α = 0.05. RESULTS: Mean coronal and sagittal interimplant angulations were 4.6 (SD = 2.9) and 3.5 (SD = 2.6) degrees, respectively. Only with LAs a statistically significant decrease was found in retention (average 1.1 Newton; standard error = 0.38; p = .007) per 1 degree increased sagittal interimplant angulation. CONCLUSIONS: Increased interimplant angulation appears to have higher impact on the retention of LA than of RA attachments. The effect of larger interimplant angulation on the loss of attachment retention and its clinical implications should be further assessed.

The role of enamel crystallography on tooth shade.

OBJECTIVES: Tooth shade is influenced by a combination of extrinsic-stains that are adsorbed to the enamel surface and by its intrinsic-shade resulting from the interaction of light with tooth structures. This study was designed to investigate how the variations in enamel ultrastructure may affect tooth optical properties. METHODS: One-hundred extracted teeth were collected from adult patients attending McGill-Undergraduate Dental Clinics. Shade-spectrophotometry, FTIR and XRD were used to assess tooth shade, enamel chemical composition and crystallography. The data obtained was analysed for Pearson correlation analysis and multiple linear regression analysis. The statistical significance was set at P < 0.05. RESULTS: Tooth shade parameters varied dramatically within the studied population. Pearson correlation analysis demonstrated that tooth hue was associated with enamel hydroxyapatite (HA) crystal size (R = -0.358; B = -0.866; P = 0.007), tooth chroma was associated with enamel HA carbonization (R = -0.419; B = -99.06; P = 0.005), and tooth lightness was associated with both enamel HA crystal size (R = -0.313; B = -1.052; P = 0.019) and the degree of HA carbonization (R = -0.265; B=-57.95; P = 0.033). Multiple linear regression analysis demonstrated that the size of enamel HA crystals and the relative content of mineral carbonate were the most important predictors for tooth shade lightness (P = 0.018) and chroma (P=0.008), respectively. In contrast, enamel organic content had no correlation with tooth shade. CONCLUSIONS: In the present study we have revealed that the tooth shade is regulated by the size of their HA enamel crystals. On the other hand, variation in the degree of enamel HA carbonization can also affect the tooth shade. These findings are of great relevance in dentistry since it provides better understanding of tooth aesthetics.