Removable dental prostheses and difficulties with chewing among frail individuals: Results from the Swiss SAPALDIA cohort.

Oral healthcare among the frail is an underestimated geriatric care element. While neglected oral health (OH) is a well-established risk factor for frailty, frailty can be a risk factor for subsequent OH problems. The cross-sectional investigation nested into the SAPALDIA sub-cohort of citizens aged 52 years and older, aims to stimulate longitudinal research into aspects that accelerate poor OH among frail individuals. The hypothesis investigated was that (pre-) frail individuals are more likely to have missing teeth replaced with removable dental prostheses (RDP) resulting in difficulties with chewing. The study included 1489 participants undergoing geriatric assessments and oral examination. The main predictor was frailty status (non-frail; pre-frail; frail), based on Fried's frailty phenotype. The main outcomes of interest were non-functional dentition (presence of ≤ 19 natural teeth), presence of any RDP and self-reported difficulties with chewing. Pre-frailty and frailty were not associated with the presence of ≤ 19 natural teeth, but were associated with a higher RDP prevalence. The presence of at least one complete denture (CD) had 1.71 fold and 2.54 folds higher odds among pre-frail and frail, respectively, compared to non-frail individuals. Frail individuals with CD reported chewing difficulties 7.8 times more often than non-frail individuals without CD. The results are in line with the hypothesis that (pre-) frail individuals may be more likely to have tooth loss restored by RDPs. Future longitudinal research needs to assess potential barriers to oral hygiene and fixed dental prostheses among (pre-) frail and to study their oral health-related quality of life.

Medium-Term Observation of Dalbo-Rotex Retention Elements: A Retrospective Cohort Study.

PURPOSE: To investigate the medium-term survival of Dalbo-Rotex retention elements, identify potential risk factors for complication or loss, and to consider economic factors. MATERIALS AND METHODS: Patients treated with Dalbo-Rotex retention elements in a university setting were retrospectively identified and examined. Clinical data comprised assessments of the dental, periodontal, endodontic, and prosthetic situation, including radiographic analysis. Patient satisfaction was quantified with visual analog scale questionnaires. Five-year Kaplan-Meier plots for relative survival and success rates were calculated. RESULTS: The 45 included patients had a total of 76 Dalbo-Rotex retention elements. Twelve Dalbo-Rotex elements failed and complications occurred in 42.1% of elements, equating to a survival rate of 84.2% and a success rate of 47.4% after a mean observation period of 49.2 months (SD 52.4, range 6-219 months). The 5-year cumulative survival and success rate was 62.4% (95% CI 44.0-88.4%) and 35.6% (95% CI 23.8-53.2%), respectively. Patients' self-assessment of prostheses retention was rated at 82 (IQR 40-92.2) with low pain perception at 4.5 (IQR 0-30). Probing pocket depth levels were significantly reduced in patients adhering to a regular recall interval compared with those with longer intervals. CONCLUSIONS: Chairside Dalbo-Rotex retention elements are a straightforward chairside method for prostheses retention that achieve good survival over medium-term follow up with high patient satisfaction. This technique is therefore a viable alternative to cast post copings that may be particularly valuable for patients with limited financial resources.

Effect of implant type on the stability of cantilever fixed dental prostheses: An in vitro study.

OBJECTIVES: To simulate the replacement of a premolar with an implant-supported cantilever fixed dental prosthesis (ICFDP) and how the fracture load is affected by implant type, positioning within the zirconia blank, and aging protocol. MATERIALS AND METHODS: Seventy-two ICFDPs were designed either within the enamel- or dentin layer of a 4Y-PSZ blank for bone-level and tissue-level titanium-zirconium implants. Fracture load was obtained on the cantilever at baseline (no aging) or after aging in a chewing simulator with the load applied within the implant axis (axial aging) or on the cantilever (12 groups with n = 6). A three-way ANOVA was applied (α = .05). RESULTS: A three-way ANOVA revealed a significant effect on fracture load values of implant type (p = .006) and aging (p < .001) but not for the position within the zirconia blank (p = .847). Fracture load values significantly increased from baseline bone level (608 ± 118 N) and tissue level (880 ± 293 N) when the implants were aged axially, with higher values for tissue level (1065 ± 182 N) than bone level (797 ± 113 N) (p < .001). However, when the force was applied to the cantilever, fracture load values decreased significantly for tissue-level (493 ± 70 N), while values for bone-level implants remained stable (690 ± 135 N). CONCLUSIONS: For ICFDPs, the use of bone-level implants is reasonable as catastrophic failures are likely to be restricted to the restoration, whereas with tissue-level implants, the transmucosal portion of the implant is susceptible to deformation, making repair more difficult.

Shear bond strength of universal adhesives to human enamel and dentin.

OBJECTIVE: The composition of universal adhesives is highly diverse. The purpose of this in vitro study was to compare the shear bond strength of a composite with five different universal adhesives to human enamel and dentin. MATERIALS AND METHODS: The shear bond strength of a composite (G-aenial Universal Injectable) to human enamel and dentin was tested in selective enamel etching mode before and after thermocyclic aging (10,000 cycles) using five different universal adhesive systems (Adhese Universal VivaPen, Clearfil Universal Bond Quick, G-Premio Bond, Prime&Bond active, and Scotchbond Universal Plus). Two-bottle systems (OptiBond FL and G2-Bond Universal) were used as control. Scanning electron microscopy was conducted of the bonding interface. RESULTS: Significant differences in shear bond strength values were found among the five evaluated universal adhesives. Lowest shear bond strength values were observed for 2-hydroxyethylmethacrylate (HEMA)-free systems. Thermocyclic aging did not significantly reduce shear bond strength values indicating that the initial bond remains stable. CONCLUSIONS: The clinical use of universal adhesives Adhese Universal VivaPen, Clearfil Universal Bond Quick, and Scotchbond Universal Plus can be encouraged as they provided comparable or even better shear bond strength values than the two-bottle controls. CLINICAL SIGNIFICANCE: Universal adhesives that were developed for the same indication and approved for clinical use demonstrated variety in shear bond strength values. When applied in the selective enamel etching mode, a stable bond can be expected from adhesives containing HEMA and monomers with phosphate groups.

Effectiveness of a manual test at the beginning of dental school.

INTRODUCTION: This study analysed whether the SAZAMED (Self-assessment for dentistry studies) manual test conducted as an exercise or examination in the first year of dental studies, and the official aptitude test for medical studies (EMS), can predict future performance of dental students. MATERIALS AND METHODS: Students enrolled in the dental curriculum at the University of Basel between 2009/10 and 2019/20 were categorized: Group A conducted the SAZAMED in the third bachelor year (BA) and second master year (MA), group B practiced in the first and third BA and second MA and group C had to pass the test in the first BA with repetition in the third BA and second MA. SAZAMED comprised (i) wire bending, (ii) modelling sphere and cube, (iii) drawing mirror-inverted and (iv) indirect drawing over a mirror. Comparative variables were the EMS per cent rank and test scores in practical-clinical examinations in the third BA and the second MA. RESULTS: Data were available from 329 students over the 10-year period. Repeaters and dropouts had poorer performance in the first BA SAZAMED than students who did not (p < 0.001). Among the four SAZAMED exercises, mirror-inverted drawing was the strongest predictor of future student performance. The official aptitude test EMS correlated with the third BA certificate (p = 0.012), but failed to predict repeaters and dropouts. CONCLUSION: Since academic success was associated with significantly better scores on the first BA SAZAMED, it is considered a predictor and recommended in addition to the official EMS to identify students in need of intervention programmes or who should choose a different field of study.

Clinical performance of single implant prostheses restored using titanium base abutments: A systematic review and meta-analysis.

PURPOSE: The aim of this review was to evaluate the survival rates of restorations utilizing titanium base abutments (TBA) for restoring single-unit implant prostheses. MATERIALS AND METHODS: This review was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. The focus question was: In patients who require the restoration of a single dental implant utilizing a titanium base abutment, what are the determining factors and outcomes relating to implant prosthesis prognosis and survival? A comprehensive search of databases (PubMed, EMBASE, and Cochrane Library) was conducted on 16 April 2023 and updated on 5 May 2023. Randomized clinical trials (RCT), retrospective studies and prospective studies, reporting on the use of TBA for single implant prostheses, were reviewed. A Cochrane collaboration risk of bias assessment analysis was performed for randomized clinical studies, and the Newcastle-Ottawa Scale tool was applied for non-randomized studies. A meta-analysis was performed on clinical trials reporting on survival rates of both TBA and other abutments. Other clinical studies, reporting on TBA only, were included for descriptive statistics. RESULTS: The search provided 1159 titles after duplicates were removed. Six RCTs were included to perform a meta-analysis and compare the survival of the TBA to other abutments [OR 0.74; 95% CI: 0.21-2.63, heterogeneity; I2 0%; p = .99]. Twenty-three prospective and retrospective studies fulfilled the criteria and were included in the meta-analysis after 12 months of function. A total of 857 single implant-supported prostheses fabricated with a TBA were included. TBA abutments have an estimate 98.6% survival rate after 1 year in function (95% CI: 97.9%-99.4%). The mean follow-up period was 31.2 ± 16.9 months. CONCLUSIONS: Single implant prosthesis restored with titanium base abutments showed favourable short-term survival rates.

Biofilm formation on metal alloys and coatings, zirconia, and hydroxyapatite as implant materials in vivo.

OBJECTIVES: Composition of implant material and its surface structure is decisive for oral biofilm accumulation. This study investigated biofilm formation on eight different materials. MATERIALS AND METHODS: Eighteen healthy subjects wore intraoral splints fitted with two sets of eight materials for 24 h: zirconia [ZrO2 ]; silver-gold-palladium [AgAuPd]; titanium zirconium [TiZr]; Pagalinor [PA]; hydroxyapatite [HA]; silver-platinum [AgPt]; titanium aluminum niobium [TAN]; titanium grade4 [TiGr4]. Total biomass was stained by safranin to assess plaque accumulation while conventional culturing (CFU) was conducted to investigate viable parts of the biofilm. Cell viability of human gingival fibroblasts (HGF-1) was assessed in vitro. Statistical evaluation was performed with linear mixed-effects models to compare materials (geometric mean ratios, 95% CI), with the level of significance set at ɑ = .05. RESULTS: Less biofilm mass and CFU were found on noble metal alloys (AgPt, AgAuPd, and PA). Compared to AgPt, PA had 2.7-times higher biofilm mass value, AgAuPd was 3.9-times, TiGr4 was 4.1-times, TiZr was 5.9-times, TAN was 7.7-times, HA was 7.8-times, and ZrO2 was 9.1-times higher (each p < .001). Similarly, CFU data were significantly lower on AgPt, AgAuPd had 4.1-times higher CFU values, PA was 8.9-times, TiGr4 was 11.2-times, HA was 12.5-times, TiZr was 13.3-times, TAN was 16.9-times, and ZrO2 was 18.5-times higher (each p < .001). HGF-1 viability varied between 47 ± 24.5% (HA) and 94.4 ± 24.6% (PA). CONCLUSION: Noble alloys are considered as beneficial materials for the transmucosal part of oral implants, as less biofilm mass, lower bacterial counts, and greater cell viability were detected than on titanium- or zirconia-based materials.

Implications of large language models such as ChatGPT for dental medicine.

OBJECTIVE: This article provides an overview of the implications of ChatGPT and other large language models (LLMs) for dental medicine. OVERVIEW: ChatGPT, a LLM trained on massive amounts of textual data, is adept at fulfilling various language-related tasks. Despite its impressive capabilities, ChatGPT has serious limitations, such as occasionally giving incorrect answers, producing nonsensical content, and presenting misinformation as fact. Dental practitioners, assistants, and hygienists are not likely to be significantly impacted by LLMs. However, LLMs could affect the work of administrative personnel and the provision of dental telemedicine. LLMs offer potential for clinical decision support, text summarization, efficient writing, and multilingual communication. As more people seek health information from LLMs, it is crucial to safeguard against inaccurate, outdated, and biased responses to health-related queries. LLMs pose challenges for patient data confidentiality and cybersecurity that must be tackled. In dental education, LLMs present fewer challenges than in other academic fields. LLMs can enhance academic writing fluency, but acceptable usage boundaries in science need to be established. CONCLUSIONS: While LLMs such as ChatGPT may have various useful applications in dental medicine, they come with risks of malicious use and serious limitations, including the potential for misinformation. CLINICAL SIGNIFICANCE: Along with the potential benefits of using LLMs as an additional tool in dental medicine, it is crucial to carefully consider the limitations and potential risks inherent in such artificial intelligence technologies.

The Complete Digital Workflow in Fixed Prosthodontics Updated: A Systematic Review.

Digital applications have changed therapy in prosthodontics. In 2017, a systematic review reported on complete digital workflows for treatment with tooth-borne or implant-supported fixed dental prostheses (FDPs). Here, we aim to update this work and summarize the recent scientific literature reporting complete digital workflows and to deduce clinical recommendations. A systematic search of PubMed/Embase using PICO criteria was performed. English-language literature consistent with the original review published between 16 September 2016 and 31 October 2022 was considered. Of the 394 titles retrieved by the search, 42 abstracts were identified, and subsequently, 16 studies were included for data extraction. A total of 440 patients with 658 restorations were analyzed. Almost two-thirds of the studies focused on implant therapy. Time efficiency was the most often defined outcome (n = 12/75%), followed by precision (n = 11/69%) and patient satisfaction (n = 5/31%). Though the amount of clinical research on digital workflows has increased within recent years, the absolute number of published trials remains low, particularly for multi-unit restorations. Current clinical evidence supports the use of complete digital workflows in implant therapy with monolithic crowns in posterior sites. Digitally fabricated implant-supported crowns can be considered at least comparable to conventional and hybrid workflows in terms of time efficiency, production costs, precision, and patient satisfaction.

Patient-reported outcome measures compared to professional dental assessments of monolithic ZrO2 implant fixed dental prostheses in complete digital workflows: A double-blind crossover randomized controlled trial.

PURPOSE: This double-blind randomized controlled trial analyzed patient-reported outcome measures in terms of subjective patient satisfaction compared to objective dental evaluation of prosthetic treatment with 3-unit monolithic zirconium dioxide implant fixed dental prostheses (iFDPs) in 3 digital workflows. MATERIAL AND METHODS: Twenty patients were restored with 3 iFDPs each on Straumann TL-implants with 2 completely digital workflows using different intraoral optical scanning systems with model-free fabrication of the restoration (Trios 3/3Shape [Test-1]; Virtuo Vivo/Straumann [Test-2]), and mixed analog-digital workflow with conventional impressions and digitized gypsum casts (Impregum/3M Espe [Control]). The order of impression-taking and the prosthetic try-in were randomly allocated. Sixty iFDPs were compared for patient satisfaction and dental evaluation using ANOVA. RESULTS: For iFDP evaluation, patients generally provided more favorable ratings than dental experts, regardless of the workflow. ANOVA revealed no significant difference for overall satisfaction when comparing Test-1, Test-2, or Control, either for patients (f-ratio: 0.13; p = 0.876) or dentist (f-ratio: 1.55: p = 0.221). Secondary, patients clearly favored the digital impression workflows over the conventional approach (f-ratio: 14.57; p < 0.001). Overall, the 3Shape workflow (Test-1) received the highest scores for all analyses. CONCLUSIONS: The different digital workflows demonstrated minor influence on the subjective and objective evaluation of the monolithic zirconium dioxide iFDPs in nonesthetic regions; however, the dentist may significantly increase patient satisfaction by choosing intraoral scanning instead of conventional impressions. The dentist has to consider individual patients' needs to fulfill their expectations for a personalized solution.

Evaluation of diamond rotary instruments marketed for removing zirconia restorations.

STATEMENT OF PROBLEM: The high strength of zirconia makes the removal of zirconia restorations challenging and time consuming. Whether diamond rotary instruments marketed for removing zirconia restorations are more efficient is unclear. PURPOSE: The purpose of this in vitro study was to compare the efficiency of diamond rotary instruments specifically marketed to cut zirconia with the efficiency of a conventional diamond rotary instrument. MATERIAL AND METHODS: Two diamond rotary instruments marketed to cut zirconia (JOTA Zirkon Cut Z838L [JOT] and Intensiv ZirconCut Zr02/10 [IZC]) and a conventional diamond rotary instrument (Intensiv FG 334/6 [IFG]) were tested on 2 zirconia materials: 3Y-TZP (IPS ZirCAD LT) and a multilayered 4Y-TZP (IPS ZirCAD MT Multi). Zirconia specimens (2 mm) were cut under water cooling using a force of 2 N or 6 N. Cutting times and maximum temperatures at the tip of the diamond rotary instruments were recorded. The surface roughness before and after use was measured, and the elemental composition was analyzed. RESULTS: Overall, cutting times were shorter for IFG (85 seconds) and IZC (100 seconds) than for the JOT (182 seconds). Cutting times were shorter for MT zirconia than for LT zirconia. Higher temperatures (2 N: 24.6 °C, 6 N: 36.7 °C) and lower surface roughness occurred with higher cutting loads. Impurities of diamond particles were seen for JOT. The diamond particle embedding materials were either nickel alloys (IFG and JOT) or a resin material (IZC). CONCLUSIONS: Diamond rotary instruments marketed for cutting zirconia did not perform better or generate less heat compared with a conventional diamond rotary instrument. A load of 2 N with sufficient water cooling is recommended for cutting zirconia to avoid an extensive temperature increase.

Influence of surface treatment and curing mode of resin composite cements on fibroblast behavior.

BACKGROUND: Human gingival fibroblast (HGF-1) cells in the connective tissue provide an effective barrier between the alveolar bone and the oral environment. Cement margins of restorations with intrasulcular preparation or cemented implant restorations are in contact with HGF cells. However, it is unknown to what extend the cement surface finish affects the behavior of HGF cells. The purpose of this study was to compare the behavior of HGF-1 cells in contact with two different resin composite cements with three different surface treatments after light-curing and autopolymerization, respectively. METHODS: Disks of one adhesive (Multilink Automix, Ivoclar Vivadent [MLA]) and one self-adhesive (RelyX Unicem 2 Automix, 3 M [RUN]) resin composite cement were either light-cured or autopolymerized. Specimen surfaces were prepared with the oxygen inhibition layer intact, polished with P2500-grit silicon carbide paper or treated with a scaler. Cells were cultivated on the specimens for 24 h. Viability assay was performed, and cell morphology was examined with scanning electron microscopy. Additionally, roughness parameters of the specimen were analyzed with a 3D laser scanning microscope. Three-way ANOVA was applied to determine the effect of cement material, curing mode and surface treatment (a = 0.05). RESULTS: Overall, cement material (p = 0.031), curing mode (p = 0.001), and surface treatment (p < 0.001) significantly affected relative cell viability of HGF. The autopolymerized specimen with the oxygen inhibition layer left intact displayed the lowest relative cell viability (MLA 25.7%, RUN 46.6%). Removal of the oxygen inhibition layer with a scaler increased cell viability but also resulted in higher surface roughness values. CONCLUSIONS: HGF cell viability is affected by the surface treatment and the curing mode. The oxygen inhibition layer is an inhibitory factor for the viability of HGF cells. Autopolymerization enhances the cytotoxic potential of the oxygen inhibition layer.

Cellular expression of epigenetic markers and oxidative stress in periodontitis lesions of smokers and non-smokers.

OBJECTIVE: To evaluate differences in the cellular expression of epigenetic markers and oxidative stress in periodontitis lesions between current smokers and non-smokers. BACKGROUND: Tobacco smoking is recognized as one of the major risk factors for periodontitis. However, the mechanisms by which smoking affects the progression of the disease remain to be determined. METHODS: Twenty-five current smokers and 21 non-smokers with generalized severe periodontitis were included. From each patient, one soft tissue biopsy from a periodontitis site was harvested and prepared for histological analysis. The infiltrated connective tissue (ICT) was selected as the region of interest to assess the cellular expression of epigenetic markers and reactive oxygen/nitrogen species (RONS) by immunohistochemistry. RESULTS: Although the ICT of smokers and non-smokers did not differ in size or in the expression of markers for DNA damage or oxidative stress, current smokers presented with significantly lower area proportions and densities of cells positive for the epigenetic markers DNMT1 and AcH3. In addition, periodontitis lesions in current smokers presented with a diminished antimicrobial activity, as indicated by significantly lower densities and area proportions of NOX2- and iNOS-positive cells. CONCLUSIONS: Components of the host response and epigenetic mechanisms in periodontitis lesions in smokers are downregulated as opposed to lesions of non-smokers.

Stability of Cantilever Fixed Dental Prostheses on Zirconia Implants.

BACKGROUND: The objective was to determine the optimal connector size and position within zirconia disks for implant-supported cantilever fixed dental prostheses (ICFDP). METHODS: Two-unit ICFDPs (n = 60) were designed for the premolar region with connector sizes of either 9 or 12 mm2 and positioned in the enamel or dentin layer of two different types of zirconia disks. The restorations were milled and cemented onto zirconia implants. After simulated chewing for 1.2 Mio cycles, the fracture load was measured and fractures were analyzed. RESULTS: No fractures of ICFDPs or along the implants were detected after simulated aging. The mean fracture load values were significantly higher for a connector size of 9 mm2 (951 N) compared with 12 mm2 (638 N). For the zirconia material with a higher biaxial flexural strength, the fracture load values were increased from 751 to 838 N, but more implant fractures occurred. The position within the zirconia disk did not influence the fracture load. CONCLUSIONS: A connector size of 9 mm2 and a zirconia material with a lower strength should be considered when designing ICFDPS on zirconia implants to reduce the risk of fractures along the intraosseous implant portion.

Personalized workflows in reconstructive dentistry-current possibilities and future opportunities.

OBJECTIVES: The increasing collection of health data coupled with continuous IT advances have enabled precision medicine with personalized workflows. Traditionally, dentistry has lagged behind general medicine in the integration of new technologies: So what is the status quo of precision dentistry? The primary focus of this review is to provide a current overview of personalized workflows in the discipline of reconstructive dentistry (prosthodontics) and to highlight the disruptive potential of novel technologies for dentistry; the possible impact on society is also critically discussed. MATERIAL AND METHODS: Narrative literature review. RESULTS: Narrative literature review. CONCLUSIONS: In the near future, artificial intelligence (AI) will increase diagnostic accuracy, simplify treatment planning, and thus contribute to the development of personalized reconstructive workflows by analyzing e-health data to promote decision-making on an individual patient basis. Dental education will also benefit from AI systems for personalized curricula considering the individual students' skills. Augmented reality (AR) will facilitate communication with patients and improve clinical workflows through the use of visually guided protocols. Tele-dentistry will enable opportunities for remote contact among dental professionals and facilitate remote patient consultations and post-treatment follow-up using digital devices. Finally, a personalized digital dental passport encoded using blockchain technology could enable prosthetic rehabilitation using 3D-printed dental biomaterials. CLINICAL SIGNIFICANCE: Overall, AI can be seen as the door-opener and driving force for the evolution from evidence-based prosthodontics to personalized reconstructive dentistry encompassing a synoptic approach with prosthetic and implant workflows. Nevertheless, ethical concerns need to be solved and international guidelines for data management and computing power must be established prior to a widespread routine implementation.

A comprehensive in vitro study on the performance of two different strategies to simplify adhesive bonding.

OBJECTIVE: The purpose of this study is to compare the bonding performance and mechanical properties of two different resin composite cements using simplified adhesive bonding strategies. MATERIALS AND METHODS: Shear bond strength of two resin composite cements (an adhesive cement: Panavia V5 [PV5] and a self-adhesive cement: RelyX Universal [RUV]) to human enamel, dentin, and a variety of restorative materials (microfilled composite, composite, polymer-infiltrated ceramic, feldspar ceramic, lithium disilicate and zirconia) was measured. Thermocycle aging was performed with selected material combinations. RESULTS: For both cements, the highest shear bond strength to dentin was achieved when using a primer (PV5: 18.0 ± 4.2 MPa, RUV: 18.2 ± 3.3 MPa). Additional etching of dentin reduced bond strength for RUV (12.5 ± 4.9 MPa). On enamel, PV5 achieved the highest bond strength when the primer was used (18.0 ± 3.1 MPa), while for RUV etching of enamel and priming provided best results (21.2 ± 6.6 MPa). Shear bond strength of RUV to restorative materials was superior to PV5. Bonding to resin-based materials was predominantly observed for RUV. CONCLUSIONS: While use of RUV with the selective-etch technique is slightly more labor intensive than PV5, RUV (with its universal primer) displayed a high-bonding potential to all tested restorative materials, especially to resin. CLINICAL SIGNIFICANCE: For a strong adhesion to the tooth substrate, PV5 (with its tooth primer) is to be preferred because etching with phosphoric acid is not required. However, when using a wide range of varying restorative materials, RUV with its universal primer seems to be an adequate option.

Influence of different zirconia surface treatments on biofilm formation in vitro and in situ.

OBJECTIVES: To determine whether the surface treatment of zirconia affects biofilm formation in an in vitro three-species biofilm model and in situ. MATERIAL AND METHODS: Zirconia surfaces considered for the transmucosal portion of a zirconia implant were compared with polished pure titanium grade 4 (Tp). Disks 13 mm in diameter of either polished (Zp), polished and heat-treated (Zpt), machined (Zm), machined and heat-treated (Zmt) and sandblasted, etched and heat-treated (Z14) zirconia were fabricated. Surface roughness and wettability of specimens was measured. Biofilm formation was evaluated by safranin staining and scanning electron microscopy (SEM) using a three-species model, and intraorally with 16 volunteers carrying oral splints in two independent experiments. Relative biofilm formation was compared with Kruskal-Wallis followed by Bonferroni post hoc test (α = 0.05). RESULTS: In vitro biofilm formation with optical density values on Zp (0.14 ± 0.01), Zpt (0.14 ± 0.02), Zm (0.13 ± 0.01) and Zmt (0.13 ± 0.01) was significantly lower than on Tp (0.21 ± 0.05) and Z14 (0.20 ± 0.04) (p < .05). In situ biofilm formation was significantly higher on Z14 (0.56 ± 0.45) (p < .05), while no significant differences in optical density were observed among Zp (0.25 ± 0.20), Zm (0.36 ± 0.34) and Tp (0.28 ± 0.22). SEM analysis supported quantitative findings. CONCLUSIONS: In the in vitro, three-species biofilm model differences in material and surface roughness affected biofilm formation. In situ biofilm formation was mainly affected by the surface roughness of the specimens. Polishing of zirconia is recommended to reduce biofilm formation, while heat treatment has no significant effect.

Efficacy of tooth splinting and occlusal adjustment in patients with periodontitis exhibiting masticatory dysfunction: A systematic review.

OBJECTIVE: To evaluate the efficacy of tooth splinting (TS) and occlusal adjustment (OA) compared to no TS or OA in patients with periodontitis exhibiting masticatory dysfunction. MATERIAL: The primary outcome criterion was tooth loss (TL), and the secondary outcome parameters were change in probing pocket depth (PPD), change in clinical attachment level (CAL), tooth mobility (TM), and patient-reported outcome measures (PROMs). Literature search was performed on three electronic databases (from 01/1965 to 04/2021) and focused on clinical studies with at least 12 months follow-up. RESULTS: From a total of 1515 publications, 51 articles were identified for full-text reading, of which 2 retrospective case series on TS with low risk of bias and 1 randomized and 2 prospective studies on OA with unclear risk of bias were included. For TS, synthesis of data showed that in 72 patients, 26 out of 311 teeth (weighted mean incidence of TL 8.4%) and 156 out of 1541 teeth with no TS (weighted mean incidence of TL 10.1%) were lost over 2 years following non-surgical periodontal therapy. The randomized controlled clinical trial (RCT) indicated CAL gain for teeth with OA compared to no OA. For the effect of OA on TL, PPD, and TM, heterogeneous data were retrieved from the included studies. CONCLUSIONS: Within the limitations of this review and based on a low level of evidence, it is concluded that TS does not improve survival of mobile teeth in patients with advanced periodontitis. OA on teeth with mobility and/or premature contacts may lead to improved CAL, while the effect of OA on the remaining periodontal parameters remains unclear.

Effect of repeated ultrasonic instrumentation on single-unit crowns: a laboratory study.

OBJECTIVES: This laboratory study aimed to assess the effects of ultrasonic instrumentation, simulating 10 years of supportive periodontal therapy (SPT), on single-unit crowns. MATERIALS AND METHODS: Standardized crowns were fabricated from porcelain-fused-to-metal (PFM) (n = 12), zirconia (ZrO2) (n = 12), lithium disilicate (LDS) (n = 12), feldspar ceramic (FSFC) (n = 6), and polymer-infiltrated ceramic network material (PICN) (n = 6). The crowns, luted on PICN abutments with resin-based luting material (RBLM), and if applicable glass ionomer cement (GILC), underwent thermal cycling and trimonthly ultrasonic instrumentation. After 1 and 10 years of simulated SPT, restoration quality assessments were performed, comprising profilometric surface roughness measurements, marginal integrity evaluations, and scores for luting material remnants and visible cracks. The statistical analysis included multiple logistic regressions with nested designs (α = 0.05). RESULTS: During simulated SPT, bulk fractures (n = 2) and a de-cementation failure (n = 1) of LDS and ZrO2 crowns were observed. No significant change in roughness was detected after 10 years (p = 0.078). Over time, marginal defects increased (p = 0.010), with PFM crowns showing the highest rate of chippings at sites with a narrow shoulder. Fewer marginal defects were detectable on crowns luted with RBLM compared with GILC (p = 0.005). Luting material remnants decreased during SPT (p < 0.001). Ultrasonic instrumentation caused cracks in most crown materials, in particular at sites with a narrow shoulder and in PFM crowns. CONCLUSIONS: Repeated ultrasonic instrumentation may damage single-unit crowns. PFM crowns with a narrow, all-ceramic margin are especially prone to defects. CLINICAL RELEVANCE: Frequent ultrasonic instrumentation of restoration margins of fixed dental prostheses, PFM crowns in particular, ought to be avoided.

Potential of intraoral optical scanning to evaluate motor skills' improvement for tooth preparation: A prospective cohort study.

INTRODUCTION: This prospective cohort study investigated the potential of digital assessment using intraoral scanning (IOS) combined with software analysis (prepCheck) to evaluate the outcome of repetitive tooth preparation and its influence on the acquisition of motor skills in dental students. MATERIALS AND METHODS: Twenty-six students completed 177 full-crown preparations of the same tooth in six practice sessions followed by a final examination. Preparations were assessed digitally using prepCheck and conventionally by calibrated faculty instructors. In addition, students assessed their own performance and this was compared with the instructors' assessments. RESULTS: Conventional assessment showed that students preparations improved over time, with 43.5% of students receiving score 2 (highest grade) at the fifth practice session. With the prepCheck assessment, statistically significant improvements indicated by an enlarged area within the tolerance range set at 0.2 mm were found between the first and the second practice session (7.5% improvement; 95% CI: 2.2%, 12.7%, p = 0.006), and between the first run and the final exam preparation (6.7%; 95% CI: 1.7%, 12.5%, p = 0.011). Agreement between instructor/student assessments was best immediately after students received visual feedback using prepCheck (76% agreement; Spearman's rho 0.78). CONCLUSION: These data indicate that IOS technology was useful for student's self-evaluation by visual feedback.