The effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space.

OBJECTIVES: The stability of the abutment screw is pivotal for successful implant-supported restorations, yet screw loosening remains a common complication, leading to compromised function and potential implant failure. This study aims to evaluate the effect of different implant-abutment types and heights on screw loosening in cases with increased crown height space (CHS). MATERIALS AND METHODS: In this in vitro study, a total of 64 abutments in eight distinct groups based on their type and height were evaluated. These groups included stock, cast, and milled abutments with heights of 4 mm (groups S4, C4, and M4), 7 mm (groups S7, C7, and M7), and 10 mm (groups C10 and M10). Removal torque loss (RTL) was assessed both before and after subjecting the abutments to dynamic cyclic loading. Additionally, the differences between initial RTL and RTL following cyclic loading were analyzed for each group (p < .05). RESULTS: The C10 group demonstrated the highest RTL, whereas the S4 group exhibited the lowest initial RTL percentage (p < .05). Furthermore, the study established significant variations in RTL percentages and the discrepancies between initial and postcyclic loading RTL across different abutment groups (p < .05). Additionally, both abutment types and heights were found to significantly influence the RTL percentage (p < .05). CONCLUSION: The type and height of the implant abutment affected screw loosening, and in an increased CHS of 12 mm, using a stock abutment with a postheight of 4 mm can be effective in minimizing screw loosening.

[Constructive complications in dental implantology (clinical case series)]. / Konstruktivnye oslozhneniya v dental'noi implantologii (na primere klinicheskikh sluchaev).

The aim the study. Analyze errors in planning orthopedic treatment using dental implants using the example of clinical cases. MATERIALS AND METHODS: Two patients are presented who applied for a consultation at the orthopedic and surgical department of the Federal State Budgetary Institution National Medical Research Center Central Research Institute of Chronic and Peripheral Surgery of the Russian Ministry of Health regarding a fracture of a previously installed orthopedic structure on an implant. For diagnostic purposes, computed tomography was performed to determine the condition of the implants and teeth of the upper and lower jaws. RESULTS: The patients were found to have: a fracture of an implant 4.0*10 with a single orthopedic structure in the area of tooth 4.6 (the patient did not undergo restoration of the missing tooth 4.7 in the presence of an antagonist), a fracture of small diameter implants (3.5*9) in the area of 3.6, 3.7, prosthetic combined orthopedic crowns. CONCLUSIONS: During surgical and orthopedic treatment of patients, it is necessary to strictly follow the instructions developed by the manufacturer of dental implants and the STaR recommendations.

Diagnostic accuracy of artificial intelligence versus manual detection in marginal bone loss around fixed prosthesis. a systematic review.

Objectives: The aim of the review is to evaluate the existing precision of artificial intelligence (AI) in detecting Marginal Bone Loss (MBL) around prosthetic crowns using 2-Dimentional radiographs. It also summarises the recent advances and future challenges associated to their clinical application. Methodology: A literature survey of electronic databases was conducted in November 2023 to recognize the relevant articles. MeSH terms/keywords were used to search ("panoramic" OR "pantomogram" OR "orthopantomogram" OR "opg" OR "periapical") AND ("artificial intelligence" OR "deep" OR "machine" OR "automated" OR "learning") AND ("periodontal bone loss") AND ("prosthetic crown") in PubMed database, SCOPUS, COCHRANE library, EMBASE, CINAHL and Science Direct. RESULTS: The searches identified 49 relevant articles, of them 5 articles met the inclusion criteria were included. The outcomes measured were sensitivity, specificity and accuracy of AI models versus manual detection in panoramic and intraoral radiographs. Few studies reported no significant difference between AI and manual detection, whereas majority demonstrated the superior ability of AI in detecting MBL. CONCLUSIONS: AI models show promising accuracy in analysing complex datasets and generate accurate predictions in the MBL around fixed prosthesis. However, these models are still in the developmental phase. Therefore, it is crucial to assess the effectiveness and reliability of these models before recommending their use in clinical practice.

Complications and Patient-Centered Outcomes of an Implant- Supported Single Crown After Immediate and Delayed Loading: A Systematic Review and Meta-analysis.

PURPOSE: To assess the complications, satisfaction, and quality of life of patients rehabilitated with delayed and immediate loading of single crowns. MATERIALS AND METHODS: An electronic search was conducted in PubMed/MEDLINE, Scopus, Web of Science, Cochrane Library, and Embase databases up to February 2023. Only prospective studies and randomized and nonrandomized clinical trials comparing immediate and delayed loading were included. For the quantitative analysis, dichotomous and consistent variables were evaluated with a 95% confidence interval. RESULTS: A total of 20 studies were evaluated. No statistically significant difference was observed between protocols: satisfaction (I2: 0%; P = .42), quality of life (I2: 0 %; P = .05), biologic complications (I2: 9%; P = .17), mechanical complications (I2: 58%; P = .84), and survival rate (I2: 0%; P = .38). The subgroup analysis showed significant differences only for marginal bone loss (MBL) when immediate implants were placed in the mandible (I2: 15%; P = .01) and posterior zone (I2: 0%; P = .001). CONCLUSIONS: Complications and patient-centered outcomes for immediate single-implant crowns were comparable to delayed loading. Scientific evidence showed no significant difference between loading protocols for survival rates. Note that several factors could interfere with the complication events, implant failures, and MBL. The subgroup analysis showed that only immediate implants placed in the posterior mandible had a higher and statistically significant mean MBL.

An uncommon case of native joint septic arthritis by Parvimonas micra.

Parvimonas micra is an anaerobic, Gram-positive coccus found in the oral cavity and gastrointestinal tract. We report a case of a 77-year-old male with right knee pain after a recent dental procedure and fall. Arthrocentesis was notable for Parvimonas micra which was successfully treated with metronidazole.

A case of oral foreign-body granuloma due to diatoms.

Diatoms are photosynthetic algae with a siliceous exoskeleton. Diatoms are utilized by a wide array of industries for applications such as filtration and pest control. Unsubstantiated claims have also propelled their societal reach to trendy oral and topical uses. This case highlights a rare case of an oral granuloma secondary to diatoms. An 80-year-old woman presented with a mobile, firm, asymptomatic submucosal mass on her lower left mandibular vestibular mucosa. Histopathology showed a non-caseating granulomatous reaction to diatoms. Her only verified contact with a diatomaceous earth product was a dental impression using alginate after upper front teeth trauma 5 months before. Although there have been several cases of allergic contact dermatitis attributed to diatoms, there are no reported cases of diatom-induced granuloma formation found in the literature. There are, however, ample data on granulomas initiated by silica. Given the silica-based composition of diatoms, and the broad use of diatoms in industry and alternative medicine, it is unclear why diatom-induced granulomas are not more widely described. This report may alert clinicians to the existence of diatom granulomas and incline them to tailor their history to cover questions about possible exposure when evaluating patients presenting with a localized oral lesion.

Five year evaluation of the complications observed in porcelain fused to metal (PFM) crowns placed at a university hospital.

OBJECTIVE: To determine the frequency of complications in crowns cemented over a 5-year period in a tertiary care hospital and also to report the survival of these crowns. METHODS: The retrospective cross-sectional study was conducted at the Aga Khan University Hospital, Karachi, from March 2017 to March 2018 and comprised porcelain fused-to-metal crowns placed on the anterior or posterior teeth that were fabricated at the institutional laboratory and were placed in institutional dental clinics in the preceding 5 years. Porcelain-fused to-metal The crowns were clinically and radio-graphically evaluated in a duration of two months for presence/absence of complications. Factors associated with the failure of the crowns, their survival and the impact of covariates, like gender, flossing and bruxism, on the survival time were determined. Data was analysed using SPSS 22. RESULTS: There were 150 crowns related to 107 patients who had a mean age of 45.0±11.4 years. The most common complication observed was open proximal contacts 9(6%) followed by de-cementation 8(5.3%), porcelain chipping 9(6%) and abutment fracture 2(1.3%). The 5-year survival rate of the crowns was 127(84.7%). The mean follow-up time was 57.2±1.0 months. Overall, year-wise survival of PFM crowns for one year till five years was 147 (98%), 144 (96%), 135 (90%), 130 (86%) and 119 (79%) respectively. CONCLUSIONS: The porcelain-fused-to-metal crowns had a high 5-year survival rate. Open proximal contacts represented the most common complication.

Longevity and marginal bone loss of narrow-diameter implants supporting single crowns: A systematic review.

PURPOSE: To compare the longevity and marginal bone loss of narrow-diameter (≤3.3-mm) versus standard-diameter implants supporting single crowns. MATERIAL AND METHODS: The MEDLINE (via PubMed), Scopus, and SciELO databases were searched for relevant publications. In addition, the scientific references provided by each of the implant companies that appeared in the search were reviewed. Intervention studies comparing longevity and bone loss between narrow-diameter and standard-diameter implants were included. RESULTS: The search was limited to in vivo studies in humans. The query returned 1931 results, of which 4 met the inclusion criteria. The implant success rate ranged from 93.8% to 100% over a maximum follow-up of 3 years, with no difference between narrow- and standard-diameter implants. Meta-analysis of all included studies showed greater bone loss in narrow-diameter implants as compared with standard ones; however, when analysis was restricted to randomized trials, no such difference was present. CONCLUSION: The meta-analysis showed no difference in longevity between narrow implants and standard implants when supporting single crowns. However, narrow-diameter implants may be associated with greater marginal bone loss. These findings should be regarded cautiously due to the short follow-up duration and methodological heterogeneity of the primary studies.

In vitro investigation of human enamel wear by dental porcelain.

BACKGROUND: Ceramic crown that fires the layering porcelain on zirconia corping is starting to be used due to aesthetic requirements. However, many ceramics are used, but wear characteristics are often unknown. OBJECTIVE: This study was performed to investigate the wear of human enamel by porcelains, and to determine the influence of porcelain hardness, surface roughness and crystal of porcelain on the enamel wear. METHODS: Enamel specimens were prepared from extracted human molar teeth. Porcelain specimens were prepared from Deguceram Gold, Vita Omega 900, and Cercon Ceram Kiss. Enamel wear volume was calculated and the porcelain wear depth, surface roughness and Vickers hardness was measured. Moreover, the observation of a crystal by scanning electron microscope and the crystal by X-ray diffraction were identified. RESULTS: Omega 900 showed the smallest enamel wear volume and porcelain wear depth. The Vickers hardnesses of Omega 900 and Cercon Ceram Kiss were almost identical. Leucite was detected from Deguceram Gold and Omega 900, and Silica and Silicon Nitride were detected from Cercon Ceram Kiss. CONCLUSIONS: The enamel wear is influenced not by the hardness of the porcelain but by the surface roughness, the size and shape of the crystal.

[Acute Facial Swelling Following Dental Procedure - an Allergic Reaction?] / Akute Gesichtsschwellung nach Zahnbehandlung: eine allergische Reaktion?

The most common cause of facial edema after dental or medical treatment is an allergic reaction. At our emergency department, a 58-year old female patient presenting with swollen right face after dental crown preparation, was initially treated with antiallergic medication. After three hours the patient was stable, swelling was still present and then crepitus could be observed on second palpation. Cervicofacial subcutaneous emphysema was confirmed with an unenhanced CT of the head and paranasal sinus; it is a rare complication after dental treatment and within the last years only few cases have been reported. Reported complications are pneumothorax and -pericardium, mediastinitis or air embolism, so early recognition is important. Our case report depicts diagnostic and therapeutic steps of this uncommon differential diagnosis.

Assessment of iatrogenic damage to adjacent teeth during crown and bridge preparation.

INTRODUCTION: Iatrogenic damage to the adjacent tooth during crown preparation is a frequent disastrous effect. The aim of the study was, therefore, to determine the frequency of different types, degree and location of iatrogenic damage to the adjacent tooth during crown and bridge preparations in a tertiary care setting that lead towards the morbidity of tooth. MATERIALS AND METHODS: A prospective study was conducted in Aga Khan University dental laboratory in two months period in which a total of 150 dental casts fulfilling the inclusion criteria were analyzed using non-probability convenient sampling technique. The casts were examined using 3.5x magnifying loupes for the location, degree and type of damage to the proximal surface adjacent to the prepared tooth using Moonpar and Faulkner criteria. Data were analyzed by using SPSS version 22. Chi square test was used to assess the association between the experience of practitioner and degree of damage to adjacent tooth. It was also used to determine the association between location of tooth and degree of damage to adjacent tooth. Inter-examiner reliability was assessed by using kappa statistics. RESULTS: A high prevalence of damage to the proximal surface of adjacent teeth (78% on mesial tooth and 60.6% on distal tooth) was observed, with the majority (32.6%) belonging to the mild categories. There were statistically significant associations between the experience of practitioner and the damage to the surface mesial to the preparation. However, more severe damages occurred in mandibular teeth preparations as compared to maxillary teeth preparations. CONCLUSIONS: A high frequency of iatrogenic damage to the adjacent teeth had been found during crown and bridge work with the middle of the tooth as the most susceptible site. However, the majority of damages were of milder type including only abrasions.

An in vitro evaluation of nickel and chromium release from different commercially available stainless steel crowns.

AIM: The aim of the present study was to estimate nickel and chromium release from commercially available stainless steel crowns (SSCs) in artificial saliva. MATERIALS AND METHODS: Ten crowns from three manufacturers were immersed in 10 ml of artificial saliva and stored in separate tubes in an incubator at 37°C for 28 days. The crowns were removed from each tube on every 7th day, and placed in other tubes with fresh artificial saliva. Flame type atomic absorption spectrophotometer was used to check for the release of metal ions in the solution inside each tube at the end of 1, 7, 14, 21, and 28 days and the control samples. RESULTS AND STATISTICAL ANALYSIS: Two-way analysis of variance and pairwise comparison using Bonferroni test was used for statistical analysis. There was statistically verified difference in the release of nickel and chromium on different days in each of the group of SSCs tested. However, no significant difference was seen in the release of both metals among the groups. CONCLUSION: In all the SSCs tested, there was the release of nickel and chromium, but the total release of both the metals even at a period of 28 days was below the critical level to cause any toxic effects. Hence, the release of metal ions should not be an alarming concern for the use of any of the group of commercially available SSCs.

Association Between Early Implant Failure and Prosthodontic Characteristics.

PURPOSE: To identify associations between early implant failure and prosthodontic characteristics that could be used to guide subsequent continuous quality improvement efforts of patient care. MATERIALS AND METHODS: An implant-level analysis was performed in which data were abstracted from a prospective clinical database of all adult patients treated with implants and followed up from January 2000 through December 2014 at the Department of Dental Specialties at Mayo Clinic in Rochester, Minnesota. These data were used to determine time to implant failure. Associations between prosthodontic characteristics and early implant failure were evaluated with Cox proportional hazards regression models and summarized with hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Among 8762 implants in 2787 patients, 395 (4.5%) failed within the first year of placement at a mean (SD) of 127 (97) days (range, 2-364 days). Univariable analysis showed no associations between early implant failure and use of a cover screw, prosthesis, or definitive or provisional prosthesis at implant placement. Three of 25 single crowns failed, and use of a single crown was significantly associated with early implant failure (HR, 3.94; 95% CI, 1.08-14.35; P = 0.04). This study identified no significant associations between prosthodontic characteristics identified after implant placement and early implant failure. CONCLUSIONS: Use of a prosthesis at implant placement, use of a definitive or provisional prosthesis, and early mechanical complications were not associated with increased risk of early implant failure. Quality improvement efforts should focus on aspects of decision making that aim to decrease surgical complications.

A possible risk of CAD/CAM-produced composite resin premolar crowns on a removable partial denture abutment tooth: a 3-year retrospective cohort study.

PURPOSE: To evaluate the early performance of computer-aided design/computer-aided manufacturing (CAD/CAM)-produced composite resin crown (CAD/CAM composite crown) treatment on premolars, specifically, placement on a removable partial denture (RPD) abutment tooth, and the distalmost tooth in the dental arch, as possible clinical risk factors. METHODS: A retrospective cohort study (April 2014 to July 2017) was performed utilizing the clinical records of patients who received a premolar CAD/CAM composite crown treatment. The variables of time of treatment for (1) successful crowns (complication event-free) and (2) surviving crowns (clinically functional including re-luted) were estimated using Kaplan-Meier analysis. Survival distributions regarding "RPD abutment tooth" and "distalmost tooth" were analyzed with the log-rank test. Multilevel survival analyses were used to identify hazard ratios and associated risk factors. RESULTS: Five hundred and forty-seven crowns were evaluated (mean follow-up time 1.3±0.9years) in 327 patients. A total of 87 crowns had at least one complication, with loss of crown retention being the most common (70 crowns). Estimated success and survival rates at 3 years were 71.7% and 96.4%, respectively. The risk of complications was significantly higher for an RPD abutment tooth than for a non-RPD abutment tooth. There was no significant difference between the distalmost tooth and non-distalmost tooth in the dental arch. CONCLUSIONS: The demonstrated complication rate for CAD/CAM composite crowns placed on premolars was 15.9% over a period of up to 3 years. There was a substantial risk of complications with placement of such a crown on an RPD abutment tooth.

A systematic review of the influence of the implant-abutment connection on the clinical outcomes of ceramic and metal implant abutments supporting fixed implant reconstructions.

OBJECTIVES: The objective of this systematic review was to assess the influence of implant-abutment connection and abutment material on the outcome of implant-supported single crowns (SCs) and fixed dental prostheses (FDPs). METHODS: An electronic Medline search complemented by manual searching was conducted to identify randomized controlled clinical trials, prospective and retrospective studies with a mean follow-up time of at least 3 years. Patients had to have been examined clinically at the follow-up visit. Failure and complication rates were analyzed using robust Poisson regression, and comparisons were made with multivariable Poisson regression models. RESULTS: The search provided 1511 titles and 177 abstracts. Full-text analysis was performed for 147 articles resulting in 60 studies meeting the inclusion criteria. Meta-analysis of these studies indicated an estimated 5-year survival rate of 97.6% for SCs and 97.0% for FDPs supported by implants with internal implant-abutment connection and 95.7% for SCs and 95.8% for FDPs supported by implants with external connection. The 5-year abutment failure rate ranged from 0.7% to 2.8% for different connections with no differences between the types of connections. The total number of complications was similar between the two connections, yet, at external connections, abutment or occlusal screw loosening was more predominant. Ceramic abutments, both internally and externally connected, demonstrated a significantly higher incidence of abutment fractures compared with metal abutments. CONCLUSION: For implant-supported SCs, both metal and ceramic abutments with internal and external connections exhibited high survival rates. Moreover, implant-supported FDPs with metal abutments with internal and external connections for also showed high survival rates.

The clinical performance of all-ceramic implant-supported single crowns: A systematic review and meta-analysis.

OBJECTIVE: This review aimed at evaluating the survival and technical complication rates of all-ceramic implant-supported single crowns (SC). MATERIAL AND METHODS: Three electronic databases were searched for clinical studies conducted at ≥ 15 patients examining implant-supported all-ceramic SCs over ≥ 12 months. Survival rates of implants and restorations plus technical complication rates of SCs were calculated and tested for statistical correlation with confounding variables. Statistical analysis was performed using a negative binomial distribution model to calculate 5- and 10-year survival and complication estimates. RESULTS: Forty-one included studies reported on implant-supported SCs made of veneered and monolithic high-strength oxide ceramics, monolithic, and veneered glass-based ceramics and of a monolithic resin-nano-ceramic (RNC). Survival estimates for SCs of 93% (95% CI: 86.6%-96.4%) after 5 years and 94.4% (95% CI: 91.1%-96.5%) after 10 years were calculated, corresponding values for implant survival were 95.3% (95% CI: 90.6%-97.7%) and 96.2% (95% CI: 95.1%-97.1%). Technical complication rates after 5/10 years were as follows: chipping 9.0% (95% CI: 5.4%-14.8%)/2.7% (95% CI: 2.1%-3.5%), framework fractures 1.9% (95% CI: 0.7%-4.9%)/1.2% (95% CI: 1%-1.5%), screw loosening 3.6% (95% CI: 1.6%-8.4%)/5.2% (95% CI: 3.6%-7.5%), and decementations with 1.1% (95% CI: 0.4%-2.8%) after 5 years. Some confounding variables influenced the above-mentioned estimates significantly. CONCLUSIONS: All-ceramic implant-supported SCs showed-with the exception of a RNC material-high survival rates. However, failures and technical complications occurred which have to be considered when informing patients on the treatment with implant-supported all-ceramic SCs.

Biomechanical aspects: Summary and consensus statements of group 4. The 5th EAO Consensus Conference 2018.

OBJECTIVES: The aim of the present publication was to report on the EAO Workshop group-4 discussions and consensus statements on the five reviews previously prepared. These reviews provided the scientific evidence on the effect of crown-to-implant ratio, on reconstructions with cantilevers in fully and partially edentulous patients, on biological and technical complications of tilted in comparison with straight implants, and on the effects of osseointegrated implants functioning in a residual dentition. MATERIAL AND METHODS: The group discussed, evaluated, corrected where deemed appropriate, and made recommendations to the authors regarding the following five reviews submitted: (a) Is there an effect of crown-to-implant ratio on implant treatment outcomes?; (b) Implant-supported cantilevered fixed dental rehabilitations in fully edentulous patients; (c) and in partially edentulous patients; (d) Biological and technical complications of tilted implants in comparison with straight implants supporting fixed dental prostheses; (e) What are the adverse effects of osseointegrated implants functioning among natural teeth of a residual dentition? Based on the five manuscripts and the discussion among the group as well as the plenum members, the major findings were summarized, consensus statements were formulated, clinical recommendations were proposed, and areas of future research were identified. RESULTS: Crown-to-implant ratios ranging from 0.9 to 2.2 did not influence the occurrence of biological or technical complications also in single-tooth restorations. Reconstructions with cantilevers for the rehabilitation of fully and partially edentulous jaws showed high implant and reconstruction survival rates. In contrast, the rate of complications-in particular associated with veneering material-was high during the observation period of 5-10 years. The data reported were primarily derived from studies with high risk of bias. The data for single-implant reconstructions were small. There was no evidence that distally tilted implants were associated with higher failure rates and increased amounts of marginal bone loss. The data supporting these findings, however, were at high risk of bias and frequently incompletely reported. Frequent positional changes occurred between the natural teeth and the implant-supported restorations. These changes were more pronounced in younger individuals, and even though they were reduced with age, they still occurred in adult patients. Even though these changes were frequent, potential implications for the patient are unclear. CONCLUSIONS: The use of single-tooth restorations with crown-to-implant ratio in between 0.9 and 2.2 may be considered a viable treatment option. Multiunit reconstructions with cantilevers are a viable treatment option in fully and partially edentulous patients. Clinicians and patients should be aware, however, that complications are frequent and primarily related to resin material used for veneering. There is some evidence that tilting an implant does affect stability of the implant and the surrounding bone. Treatment options to tilted implants should carefully be considered, as the effect on soft tissues and on prosthesis behavior is poorly reported for tilted implants. Positional changes in the dentition in relation to implant-supported restorations occur frequently. The patient should be informed about the possible need for a treatment related to these changes in the long term.

Is there an effect of crown-to-implant ratio on implant treatment outcomes? A systematic review.

OBJECTIVES: High crown-to-implant ratios may lead to complications due to unfavorable occlusal forces, including nonaxial forces, on the bone surrounding the neck of the implant and within the connection of the crown and implant itself. The aim of this study was to perform a systematic review on the influence of crown-to-implant ratio of single-tooth, nonsplinted, implants on biological and technical complications. MATERIALS AND METHODS: MEDLINE (1950-January 2018), EMBASE (1966-January 2018), and Cochrane Central Register of Controlled Trials database (1800-January 2018) were searched to identify eligible studies. Inclusion criteria were as follows: crown-to-implant ratio of single-tooth, nonsplinted, implant-supported restorations in the posterior maxilla or mandible and follow-up of at least 1 year. Main outcome measures were as follows: implant survival rate, marginal bone level changes, biological complications, and technical complications. Two reviewers independently assessed the articles. A meta-analysis was carried out for implant survival rate and peri-implant bone changes. RESULTS: Of 154 primarily selected articles, eight studies fulfilled the inclusion criteria. Study groups presented a mean crown-to-implant ratio varying from 0.86 (with 10-mm implants) to 2.14 (with 6-mm implants). The meta-analysis showed an implant survival of more than 99% per year and mean peri-implant bone changes of <0.1 mm per year. Limited biological and technical complications were reported. CONCLUSION: Data reviewed in the current manuscript on crown-to-implant ratio, ranging from 0.86 to 2.14, of single-tooth, nonsplinted, implants did not demonstrate a high occurrence of biological or technical complications.