Search Results (80)

Background/Objectives: Full-arch implant-supported prostheses have become a widely accepted solution for edentulous patients, yet long-term biological and mechanical complications remain a clinical concern. Methods: This retrospective study included 70 fully edentulous patients (362 implants) rehabilitated with either fixed or removable implant-supported prostheses. Data were collected on demographics, medical status, type and location of prostheses, implant type, abutments, method of fixation, and complications. Statistical analysis included Fisher’s exact test, the Mann–Whitney U test, and chi-squared tests, with a significance level set at p < 0.05. Results: Mechanical complications occurred in 41.4% of patients (29 out of 70), with framework fractures reported in eight cases (27.6%), ceramic chipping in six cases (20.7%), and resin discoloration in four cases (13.8%). The prostheses were fabricated using monolithic zirconia, metal–ceramic crowns, zirconia on titanium bars, and hybrid resin/PMMA on cobalt–chromium frameworks. Gingival inflammation was also noted in 41.4% of cases (n = 29), predominantly in posterior implant regions. Younger patients and those without systemic diseases showed a significantly higher incidence of mechanical complications. Conclusions: Two years post-treatment, mechanical and biological complications appear to be independent phenomena, not significantly associated with most prosthetic variables. Patient-specific factors, particularly age and general health status, may have greater predictive value than prosthetic design. Limitations of the study include its retrospective design and the lack of radiographic data to assess peri-implant bone changes. Full article

Background: In modern dentistry, alveolar socket preservation after tooth extraction plays a critical role in maintaining the alveolar ridge for future dental implants. This retrospective clinical study evaluated bone-level changes 15 years after immediate implant placement, coupled with alveolar ridge preservation. Methods: Fifty non-smoking patients aged 25 to 75 (30 males and 20 females) who underwent single-implant rehabilitation in both anterior and posterior regions of the upper and lower jaws were included. The study examined bone levels and implant survival over time, using standardized intraoral radiographs at 1, 5, and 15 years post-loading. Implants were placed immediately after atraumatic extraction, and the residual gap was grafted with bovine hydroxyapatite and covered with a collagen membrane. The primary outcome was bone-level stability, while secondary outcomes included implant failure. No temporary crowns or removable dentures were provided during healing. Radiographs were digitized for detailed analysis. Results: The results for 50 patients with immediate implant placement showed that bone-resorption levels were significantly higher in the upper jaw than in the lower jaw. Conclusions: Posterior implants exhibited greater bone loss than anterior implants, particularly at 1 year and 15 years, while no implant failures occurred. Full article

This study aimed to evaluate prosthetic complications, implant survival rates, and marginal bone loss in implant-supported monolithic restorations compared to metal-ceramic restorations. The study was registered in PROSPERO (CRD420251022336) and conducted following the Cochrane Handbook for Systematic Reviews of Interventions and PRISMA guidelines. A systematic search was conducted in the electronic databases MEDLINE/PubMed, Web of Science, Scopus, Embase, and ProQuest for articles published up to December 2024. The inclusion criteria comprised studies evaluating only randomized clinical trials that evaluated implant-supported monolithic restorations directly compared to metal-ceramic restorations, considering any type of ceramic material and regardless of the fixation system (screw-retained or cemented), with a minimum follow-up of one year. A meta-analysis was performed using RevMan 5.4 software, and the risk of bias and certainty of evidence were assessed using the RoB 2.0 and GRADE tools, respectively. A total of six studies were included, all of which exclusively evaluated monolithic zirconia single crowns over follow-up periods ranging from 1 to 3 years. None of the included studies evaluated fixed partial dentures or restorative materials other than monolithic zirconia. In total, 267 patients (mean age range: 18–57 years) were analyzed, with a total of 174 implant-supported monolithic zirconia crowns and 165 metal-ceramic single crowns in the posterior region (premolars and molars). The meta-analysis revealed that implant-supported monolithic zirconia single crowns exhibited significantly fewer prosthetic complications compared to metal-ceramic single crowns (p < 0.0001; Risk Ratio [RR]: 0.26; Confidence Interval [CI]: 0.14–0.47). However, no statistically significant differences were observed between implant-supported monolithic zirconia and metal-ceramic single crowns regarding implant survival rates (p = 0.36; RR: 1.66; CI: 0.56–4.94) or marginal bone loss (p = 0.15; Mean Difference [MD]: −0.05; CI: −0.11–0.02). The risk of bias assessment indicated that four studies had a low risk of bias. However, the certainty of evidence was classified as low for prosthetic complications and implant survival rates and very low for marginal bone loss. Within the limitations of this review, it can be concluded that implant-supported monolithic zirconia single crowns can be considered a favorable treatment option as they show comparable implant survival and bone stability to metal-ceramic crowns, with a potential reduction in short-term prosthetic complications such as screw loosening and ceramic chipping. However, due to the limited number of studies included and low certainty of evidence, further long-term research is still needed to confirm their clinical performance over time. Full article

Although the manual classification of microfossils is possible, it can become burdensome. Machine learning offers an alternative that allows for automatic classification. Our contribution is to use machine learning to develop an automated approach for classifying images of Pectinodon bakkeri teeth. This can be expanded for use with many other species. Our approach is composed of two steps. First, PCA and K-means were applied to a numerical dataset with 459 samples collected at the Hanson Ranch Bonebed in eastern Wyoming, containing the following features: crown height, fore-aft basal length, basal width, anterior denticles, and posterior denticles per millimeter. The results obtained in this step were used to automatically organize the P. bakkeri images from two out of three clusters generated. Finally, the tooth images were used to train a convolutional neural network with two classes. The model has an accuracy of 71%, a precision of 71%, a recall of 70.5%, and an F1-score of 70.5%. Full article

Zirconia crowns are employed in pediatric dentistry for the complete restoration of anterior and posterior deciduous teeth. They are considered the best option due to their esthetic appeal, high strength, biocompatibility, and resistance to wear and corrosion. This study aims to evaluate the physico-chemical, cytological, and microbial properties of zirconia crowns to determine their biocompatibility, safety for surrounding tissues, and effectiveness in preventing microbial influence on tooth tissue based on their biofilm deposition potential. XRD measurements were conducted to confirm the crown composition. For the microbiological examination, a quantitative assessment of the adhesion capacity of the analyzed strains and the formation of a mixed biofilm was performed using a Zeiss Cell Observer SD confocal microscope. This study used a mixed biofilm containing Streptococcus mutans (ATCC 25175), Lactobacillus rhamnosus (ATCC 9595), Candida albicans (ATCC 90028), and Candida albicans (ATCC 10231) to simulate the oral environment and the possible dynamics created between different types of microorganisms. A direct contact method was used to assess cytotoxic properties. The zirconia crown biomaterial shows a low ability to adhere to specific microorganisms, with L. rhamnosus predominating, indicating low clinical potential for causing inflammation of the tissues surrounding the crown. The cytotoxic properties of the biomaterial were found to be at level 2, indicating moderate cytotoxicity. Their biggest flaws are price and the need for passive fitting, which involves aggressive grinding; this is a potential limitation when it occurs in children, as their cooperation with the treatment can be difficult to guarantee. Full article

Objective: Selecting suitable materials and luting agents for single crowns is critical yet challenging, as dentists must consider different factors. This study aimed to assess dentists’ preferences for materials and luting agents under different clinical conditions and evaluate the nonclinical factors influencing their preferences. Methods: A paper-based survey supplemented with photographs illustrating anterior and posterior single-crown preparation designs was used, incorporating three clinical scenarios for each as examples. Participants provided demographic data and were asked to select their preferred material and luting agent for each scenario. Comparisons between the crown material/luting agent choices and dentist/practice characteristics were performed. Significant differences were determined using the chi-square test. Results: Overall, 262 (87.3%) dentists participated in this survey. The top-selected material for anterior preparation designs was lithium disilicate; monolithic zirconia was the most selected for posterior preparation designs. Dual-cure resin was the most selected luting agent for all anterior and posterior clinical scenarios, except for posterior subgingival preparation design. There was a significant association between the dentist’s age and the selection of material and luting agent (p < 0.05) in all clinical scenarios, except for the luting agent selection in the posterior subgingival preparation designs (p < 0.05). Other nonclinical factors yielded mixed results; some preparation designs showed significant differences, while others did not, depending on the clinical scenario. Conclusions: Reliance on new materials and luting agents that require minimally invasive treatment with dental ceramics and resin cement is increasing. However, the choice of materials and luting agents is influenced by clinical presentation and nonclinical factors, making it crucial for dentists to be aware of these factors when selecting materials for single-crown restorations. Clinical Implications: An overall trend was observed for the use of strong monolithic ceramics with adhesive resin cements. These findings could assist dentists in reviewing and re-evaluating material choices in their clinical practices, both at a national and regional level. Additionally, the findings could be useful for dental policy makers, wholesale suppliers, and retail distributors in making future decisions. Full article

Background/Objectives: The socket-shield technique (SST) was developed to preserve the facial/buccal portion of a tooth root to prevent post-extraction ridge resorption. It has gained attention for use in anterior implant sites, but its application in posterior sites remains unexplored. The aim of this case report was to report a proof-of-principle case using SST in a lower molar site and evaluate its effectiveness in preserving tissues. Methods: A 34-year-old non-smoking patient with a non-restorable mandibular first molar (tooth #36) underwent immediate implant placement with the SST. The tooth’s crown was removed, and the buccal segments of the roots were retained as “shields” while the implant was placed in the center of the socket. Preoperative and postoperative cone-beam CT (CBCT) scans and clinical exams were used to assess outcomes up to 12 months. Results: The SST procedure was completed uneventfully. CBCT after 4 months and 12 months showed minimal horizontal bone loss: ~0.2 mm at 4 months; ~0.1 mm additional loss by 12 months. The peri-implant soft tissue profile remained stable, and the implant achieved osseointegration with high primary and secondary stability. Conclusions: In this clinical case, the socket-shield technique effectively preserved alveolar bone and soft tissue contours in a molar extraction site, avoiding the ridge collapse often seen post-extraction. This suggests SST may be a viable tissue preservation approach in posterior sites; however, long-term follow-up and further studies are needed to confirm sustained outcomes and validate the technique’s predictability. Full article

Background: Recently, the demand for esthetic restorations has grown dramatically and extended into the pediatric population. The prefabricated zirconia crowns (PZCs) and custom-made zirconia crowns (CZCs) are new esthetic options in pediatric dentistry. However, they are still inadequately tested for use in children. Aim: To determine the fracture resistance and failure mode of the PZC in comparison to the CZC. Materials and Methods: In this in-vitro study, thirty cobalt-chromium dies were fabricated by scanning the negative replica of a prefabricated lower first permanent molar zirconia crown. CZCs were designed and milled using two different zirconia brands: Ceramill Zolid-FX (FX) and the Highly-Translucent (HT) zirconia. Dies were randomly assigned to receive either a PZC or a CZC (n = 10 in each group). All crowns were cemented on their respective dies using glass ionomer cement. Following artificial aging, all specimens were loaded to failure. Fracture mode analysis was performed. One-way ANOVA and Bonferroni post-hoc test were used for multiple comparisons across the groups. The significant level was set at p ≤ 0.05. Results: HT zirconia had a significantly higher fracture load compared to other groups (p < 0.05). The mean fracture resistance values were: (3087 ± 385) N for HT zirconia, (2633 ± 300) N for PZCs, and (2483 ± 381) N for FX, with no statistically significant difference in fracture strengths between PZCs and FX. Conclusions: HT zirconia crowns showed the highest fracture resistance amongst all groups. The fracture loads of tested crowns exceeded the maximum posterior biteforce. When placed in permanent molars, PZC are expected to perform well under masticatory forces in children. Full article

Background/Objectives: Odontogenic tumors in pediatric patients are uncommon; among all, the intraosseous occurrence of odontogenic myxoma is very rare, accounting for almost 8.5–11.6% of all odontogenic tumors in children. The radiological appearance is highly variable and is often responsible for the diagnostic delay and treatment. Methods: We report a case of odontogenic myxoma occurring in the posterior mandible of a 12-year-old female, found on a panoramic radiograph performed for the delayed eruption of the second inferior molar, treated by conservative surgery. A comprehensive analysis of the literature was also carried out. Results: The radiological features of the presented case were unique, as the lesion was encompassed within the uncompleted (developing) dental crown still unerupted, as confirmed by the macroscopic appearance. Then, the differential diagnosis included odontogenic fibroma, immature dental pulp or follicle from a developing tooth, and ameloblastic fibrodontoma. The histological examination led to the final diagnosis of odontogenic myxoma. As for the literature analysis, after a PRISMA-based selection of the papers, a total of 23 articles (case reports and case series on odontogenic myxomas in pediatric patients, a total of 33 cases) were finally selected and studied; all the pertinent data are widely discussed within the paper. Conclusions: The current case highlights the importance of the radiological investigation in pediatric patients when a delayed eruption lasts for several months, leading to an early diagnosis necessary to avoid more aggressive surgical therapies and possible recurrence; data from the literature about site of occurrence, sex, age, kind of surgical procedure, and recurrence rate are discussed too. Full article

This study compares the mechanical properties of 5-mol% yttria partially stabilized zirconia (5Y-PSZ) materials, designed for 3D printing or milling. Three 5Y-PSZ materials were investigated: printed zirconia (PZ) and two milled zirconia materials, VITA-YZ-XT (MZ-1) and Cercon xt (MZ-2). PZ samples were made from a novel ceramic suspension via digital light processing and divided into three subgroups: PZ-HN-ZD (horizontal nesting, printed with Zipro-D Dental), PZ-VN-Z (vertical nesting, printed with Zipro-D Dental) and PZ-VN-Z (vertical nesting, printed with Zipro Dental). Key outcomes included biaxial flexural strength (ISO 6872) and Vickers hardness (n ≥ 23 samples/subgroup). Microstructure and grain size were analyzed using light and scanning electron microscopy. Printed specimens exhibited biaxial flexural strengths of 1059 ± 178 MPa (PZ-HN-ZD), 797 ± 135 MPa (PZ-VN-ZD), and 793 ± 75 MPa (PZ-VN-Z). Milled samples showed strengths of 745 ± 96 MPa (MZ-1) and 928 ± 87 MPa (MZ-2). Significant differences (α = 0.05) were observed, except between vertically printed groups and MZ-1. Vickers hardness was highest for PZ-VN-Z (HV0.5 = 1590 ± 24), followed by MZ-1 (HV0.5 = 1577 ± 9) and MZ-2 (HV0.5 = 1524 ± 4), with significant differences, except between PZ and MZ-1. PZ samples had the smallest grain size (0.744 ± 0.024 µm) compared to MZ-1 (0.820 ± 0.042 µm) and MZ-2 (1.023 ± 0.081 µm). All materials met ISO 6872 standards for crowns and three-unit prostheses in posterior regions. Full article

While investigating macrofungi diversity in Gansu province, northwestern China, five fresh and fleshy specimens were collected, which are characterized by nearly white to buff hemispherical pileus with waved margins, a disc depressed with coral to brownish red fibrillose scales, adnate to sub-decurrent lamellae with four relatively regular rows of lamellulae, a stipe that is central, hollow, frequently straight to curved; basidiospores that are globose to subglobose, 5.0–6.0 × (3.5−) 4.0–5.0 (−5.5) μm, narrowly clavate cheilocystidia predominantly, pleurocystidia and caulocystidia not observed; and a cutis pileipellis, with hyphae slightly inflated in the KOH. The results of phylogeny analysis indicated that the species forms an independent lineage in Phyllotopsidaceae based on the ITS (ITS5/ITS4) and nLSU (LR0R/LR7) dataset. Molecular clock analyses suggested the common ancestor of Neotricholomopsis emerged later than upper Cretaceous with a mean crown age of 229.36 Mya (95% highest posterior density of 129.63–343.08 Mya). These five specimens were described as an unreported taxon based on the phylogeny analysis combined with morphological examination and ecological and geographical distribution. Detailed descriptions, illustrations, and phylogenetic trees to demonstrate the placement of this species and discussions with its related species are provided. Full article

(1) Background: Dental glass–ceramics shrink during crystallization, complicating restoration manufacturing. Thermo-pressure molding was introduced to address this, with lithium disilicate crystals providing high strength. Residual tensile stresses can influence the chipping strength of single tooth crowns. (2) Methods: Insync dentine was layered onto three lithia-based disilicate core ceramics (Amber Press, IPS e.max Press) for microtensile bond strength tests. The Vickers test assessed the residual tensile stress and interfacial bonding. Porcelain-veneered posterior ceramic crowns were fabricated and subjected to axial loading, measuring fracture loads (three per group). (3) Results: A chemical bonding layer formed at the interface, which was thicker in the Insync-IPS e.max Press and increased with more firings. The ultimate tensile bond strength was 28.5 MPa for the four-times-fired Insync-Amber Press, similar to the twice-fired Insync-IPS e.max Press. No residual tensile stress was found in the Insync-Amber Press; the Insync-IPS e.max Press showed crack growth within 250 μm of the bonded interface. The average fracture resistance was twice as high for the Insync-Amber Press. (4) Conclusions: The Insync-Amber Press exhibited better thermal harmony with no crack growth, while the IPS e.max Press showed crack growth due to residual tensile stress. Insync-Amber Press posterior ceramic crowns had significantly greater fracture resistance than Insync-IPS e.max Press crowns. Full article

Objective: The aim of the present study was to evaluate the long-term clinical survival and success of chairside-fabricated single-tooth monolithic zirconia restorations on posterior teeth using the speed sintering process. Materials and Methods: Between 2012 and 2022, 250 single-tooth crowns were fabricated for 193 patients using the CEREC^® chairside workflow. Restorations were fabricated from monolithic 3Y-TZP zirconia (InCoris TZI, Dentsply Sirona©, Bensheim, Germany) as full-contour crowns. The same clinician performed all procedures. Luting was performed using self-adhesive resin-based cements or glass ionomer cement. Retrospective analysis was conducted, defining survival as crowns still in function regardless of any interventions, and success as crowns that remained functional without the need for intervention. Statistical analysis was performed using Kaplan–Meier analysis, considering “refabrication” and “intervention” as endpoints. Results: Of the 250 crowns, a total of 162 (64.8%) crowns showed success. Over the whole observation period, 44 crowns (17.6%) required refabrication, and 88 (35.2%) required intervention. Mean survival without refabrication was 7.43 years, with a 5- and 7.5-year survival of 86.9% and 76.6%. The mean survival without intervention was 6.5 years, with a 5- and 7.5-year survival of 70.8% and 59.9%. Conclusions: Under appropriate technical conditions, chairside-fabricated 3Y-TZP zirconia single-tooth crowns represent a viable fabrication method. Neither the cementation mode nor the crown position—whether on premolars or molars—significantly impacted the survival rates. Full article

Background/Objectives: The long-term effects of implant properties, such as implant length, platform switch, and crown splinting, on peri-implant health require more investigation. Therefore, the aim was to assess the long-term peri-implant health and patient satisfaction in a patient cohort, obtained from two prospective randomized controlled trials, who received 8.5 mm long dental implants, with either splinted or solitary suprastructures and with or without a platform switch, over a period of 15 years. Methods: One hundred and twenty-two patients received either one or two 8.5 mm long dental implants (223 dental implants) with and without platform switch, restored with either a solitary (n = 89) or a splinted (n = 134) restoration in the posterior region. Clinical and radiographical parameters and patient satisfaction were prospectively recorded at 1 month, and 1, 5, and 15 years after the placement of the restoration. Patient satisfaction was recorded with a self-administered questionnaire using a 5-point scale and a visual analog scale (0–10). Results: Eighty-one patients with one hundred and fifty-four implants were assessed after a 15-year follow-up. The clinical parameters were low and comparable between the implant types (OsseoTite XP Certain, OsseoTite XP Certain Prevail, NanoTite XP Certain, NanoTite XP Certain Prevail, PalmBeach Gardens, FL, USA) over time. The implants that incorporated a platform switch showed significantly less bone loss than the implants without a platform switch (−0.37 mm, 95% CI −0.69 to −0.05 mm, p = 0.024 and β = −0.47, 95% CI −0.80 to −0.14, p = 0.006). The implants with splinted restorations experienced more bone loss over time compared to the implants with solitary restorations (0.39 mm, 95% CI 0.15–0.63, p = 0.002). Patient satisfaction was high after 15 years. Conclusions: All the tested dental implants with 8.5 mm length provide satisfactory 15-year results with regard to the clinical and radiographical parameters as well as patient satisfaction. The platform-matched implants were associated with more bone loss compared to the platform-switched implants, and the implants with splinted crowns portrayed more bone loss than the solitary implant crowns. Full article

This study compares the clinical performances of two lithium disilicate (Initial LiSi press vs. Initial LiSi Block, GC Corp.) and a 3D printed resin (Temp Print, GC Corp.) partial crown using modified United States Public Health Service (USPHS) evaluation criteria and survival rates after one year of clinical service. Eighty-nine partial adhesive restorations on posterior teeth were realized using different materials: Group 1 used Initial LiSi press, Group 2 used Initial LiSi Block, and Group 3 used Temp Print. An analog workflow was used to realize the restoration of Group 1, while a fully digital workflow was used for Groups 2 and 3. The modified USPHS parameters, together with periodontal parameters, were collected at baseline and at the one-year recall. Contingency tables to assess for significant differences of success over time in each group were used. All modified USPHS parameters showed Alpha or Bravo; no Charlie was recorded. No statistically significant difference emerged between the three groups in any of the assessed variables (p > 0.05). All modified USPHS scores were compatible with the outcome of clinical success, no restoration was replaced or repaired, and the survival rate was 100% at the one-year recall. No difference was found between the traditional and digital workflows used to fabricate the restorations. Full article