Fixed, Fiber-Reinforced Resin Bridges on 5.0-mm Implants in Severely Atrophic Mandibles: Up to 5 Years' Follow-Up of a Prospective Cohort Study

Indirect restorative systems-A narrative review

OBJECTIVE

The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes.

OVERVIEW

Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth.

CONCLUSIONS

Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process.

CLINICAL SIGNIFICANCE

The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.

Polyetheretherketone CAD-CAM framework for all-on-4 mandibular full arch prosthesis: Three years' retrospective study of periimplant soft tissue changes and ridge base relationship

PURPOSE

This study was conducted to evaluate the clinical peri-implant soft tissue changes during first year after occlusal loading and the ridge base relation after three years for mandibular CAD-CAM manufactured screw-retained implant-supported hybrid prosthesis of polyetheretherketone (PEEK) framework utilized with All-on-Four treatment concept.

MATERIAL AND METHODS

Sixteen completely edentulous patients were rehabilitated by 4 implants following the All-On-Four protocol. After 3 months, the definitive prosthesis was constructed to be a screw retained CAD-CAM milled framework from the modified PEEK (BioHPP), bonded to polymethylmethacrylate (PMMA) teeth and a pink shaded indirect light-polymerized nanofilled composite resin imitating the soft tissues. Peri-implant soft tissue changes regarding plaque, bleeding, gingival scores, and probing depth were evaluated at prosthesis insertion (T0), six months (T1) and 12 months (T2) after insertion. Also, monitoring of the ridge base relation was performed using cone beam computed tomography after one year (T0), two years (T1), and three years (T2) after mandibular fixed detachable All-on-Four framework insertion. Using Shapiro Wilk tests using SPSS^® software version 22 (SPSS Inc.), all clinical data were non- parametric while the ridge base relation data was parametric.

RESULTS

There were statistically significant differences regarding plaque, gingival, and bleeding scores for all implants with advancement of time. However, there was a statistically insignificant difference regarding probing depth in the posterior implants (p = .581). Regarding ridge base relation, there was a significant difference between observation times only in the anterior ridge area in between the two anterior implants (p = .011).

CONCLUSION

Within limitations of the study, the full arch PEEK framework of fixed-detachable, hybrid prosthesis used with All-on-Four concept for rehabilitation of mandibular edentulous arches is an acceptable treatment approach. Based on the stable ridge base relation posteriorly found in this study, less stress is distributed to the underlining bone due to the shock absorbing ability of PEEK. Special considerations for frequent soft tissue follow up and regular maintenance of oral hygiene measures are recommended. This article is protected by copyright. All rights reserved.

New generation CAD-CAM materials for implant-supported definitive frameworks fabricated by using subtractive technologies

Innovations in digital manufacturing enabled the fabrication of implant-supported fixed dental prostheses (ISFDPs) in a wide variety of recently introduced materials. Computer-aided design and computer-aided manufacturing (CAD-CAM) milling allows the fabrication of ISFDPs with high accuracy by reducing the fabrication steps of large-span frameworks. The longevity of ISFDPs depends on the overall mechanical properties of the framework material including its fit, and the physical properties of the veneering material and its bond with the framework. This comprehensive review summarizes the recent information on millable CAD-CAM framework materials such as pre-sintered soft alloys, fiber-reinforced composite resins, PEEK, and PEKK in high-performance polymer family, and 4Y-TZP. Even though promising results have been obtained with the use of new generation millable CAD-CAM materials for ISFDPs, clinical studies are lacking and future research should focus on the overall performance of these millable materials in both static and dynamic conditions.

Severely Atrophic Mandibles Restored With Fiber-Reinforced Composite Prostheses Supported by 5.0-mm Ultra-Short Implants Present High Survival Rates Up To Eight Years

PURPOSE

Encouraging results have been reported for ultrashort single implants; however, long-term investigations are warranted for full-arch reconstructions. This study evaluated marginal bone loss, implant, and reconstruction survival of fiber-reinforced composite full-arch prostheses supported by 4 ultrashort implants.

METHODS

Patients with severely atrophic mandibles (Cawood and Howell class V and class VI) were included in this cohort study. Study predictors included time (initial and last follow-up) and vertical (epicrestally or subcrestally) and horizontal implant position (medial or lateral). Outcome variables included bone level changes over time, implant/prosthesis survival. Peri-implant bone level was measured on panoramic radiographs. Descriptive statistics, Kaplan-Meier, mixed model analysis of variance, and univariate and multivariate Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used for data analyses.

RESULTS

Eighteen patients (mean 61.22 years old), with 72 implants placed in atrophic mandibles with an average follow-up of 55.4 months (CI, ±4.6/ SD, ±10.6 months) were analyzed. The implant survival rate was 97.2% as 2 implants were not loaded due to non-osseointegration and sensorial disturbances. Average marginal bone level at baseline (1.93 mm) and at the time of last recall (1.91 mm) was not significantly different. While implants placed subcrestally showed no significant difference between baseline (1.91 mm) and last follow up bone level (2.12 mm), implants placed epicrestally demonstrated a significant reduction on their bone level over time (initial: 1.97 mm/ final:1.33 mm). Systemic disorders were a risk factor for implant survival and bone loss. Prostheses cumulative survival rate was 100% (mean observation period of 55 months). The estimated survival rate after the 96-month follow-up was 75% (1 framework fracture after 84 months).

CONCLUSION

Fixed fiber-reinforced composite full-arch prostheses retained by 4 ultrashort implants showed a stable bone level and high implant/prostheses survival rates up to 8 years.

A potential application of materials based on a polymer and CAD/CAM composite resins in prosthetic dentistry

PURPOSE

A bioactive high performance polymer (BioHPP) and computer-aided design/computer-aided manufacturing (CAD/CAM) composite resin materials are a relatively new class of dental biomaterials, that are biocompatible and have good aesthetic features. In this review paper, we will summarize literature and publication data on the characteristics of the mentioned materials, as well as their potential application in the dental prosthetics.

STUDY SELECTION

Available studies and literature reviews from PubMed, SCIndex, Scopus and Google Scholar corresponding to polyetheretherketone (PEEK), high-performance polymers, reinforced composite materials, composite materials, resins, glass-fiber reinforced materials, CAD/CAM materials, dental implants, removable and fixed dental were reviewed.

RESULTS

To avoid many disadvantages of metals and their alloys in dental practice, such as inadequate color, high density, thermal conductivity and possible allergic reactions, materials based on polymers (such as BioHPP), and CAD/CAM composite resins are being developed. These materials have significantly better aesthetics and physical-mechanical properties. They are biocompatible materials that are lightweight, resistant, durable, exhibit high bending and compression resistance.

CONCLUSIONS

The use of CAD/CAM composite resin materials and BioHPP in dentistry has begun recently, so the data about their potential clinical use are limited. Most of their features have been demonstrated through laboratory testing, while clinical studies are relatively scarce, so the need for further clinical trials is emphasized.

Contemplations and Ruminations of Methodological Error

PURPOSE

Journal articles in our field of oral and maxillofacial surgery are rife with case studies, cohort reviews, meta-analysis, basic science studies, surgical techniques, and anatomic studies. The data found in these studies often rely on multiple measurements by which the authors draw their conclusions. Accurate measurements play a critical role in the design of the study, which in turn affects the conclusion that the author is attempting to convey. Investigators must determine and develop the processes to determine the methodological errors associated with each project to help with determining the accuracy of these measurements. The aim of this study is to highlight some of the methodological errors contained in the material and methods in oral and maxillofacial surgery studies over the calendar years of 2018 and 2019 and how best to evaluate them.

MATERIALS AND METHODS

The inclusion criteria involved articles that used measurements where discrepancies could exist such as clinical measurements, histological measurements, and radiological measurements. The number of specimens or subjects measured in each study was tabulated.

RESULTS

Over the 2-year period considered, 744 articles were published, and 116 (15.6%) of them met the inclusion criteria. Of these articles, 37 (32%) reported a methodological error, while 79 (68%) did not. In addition, 31 (84%) of the articles with a methodological error were radiographic, while only 6 (16%) were not radiographic. Among the studies that reported methodological error, there were approximately 7 different types used with no rationale given for the choice.

CONCLUSIONS

We believe that it is important to ensure sound methods and materials, including a stated methodological error. An attempt at standardization will help to serve to enhance and strengthen the different research studies seen in our field.

Static and Fatigue Loading of Veneered Implant-Supported Fixed Dental Prostheses

PURPOSE

This study aimed to compare the load to failure and the probability of survival of porcelain fused to zirconia (PFZ) three-unit, implant-supported, fixed dental prostheses (FDPs) to those of indirect composites veneered to either zirconia (CVZ) or milled fiber-reinforced composite (FRC) frameworks under static and fatigue loading.

MATERIALS AND METHODS

One-hundred and twenty posterior three-unit FDP (second premolar pontic) frameworks were fabricated via milling from a single Standard Tessellation Language (STL) file. The FDPs were divided into three groups. Each group (n = 40) was subjected to static (n = 20) and fatigue (n = 20) loading tests, as follows: (1) PFZ: zirconia framework layered with porcelain veneer; (2) CVZ: zirconia framework veneered with indirect composite resin; and (3) FRC: FRC framework veneered with indirect composite resin. After porcelain veneering onto sintered zirconia frameworks, or resin composite veneering onto zirconia or FRC frameworks, FDPs were cemented on their abutments using self-adhesive resin cement. After thermal cycling, half of the FDPs were subjected to an accelerated fatigue test. The other half of the FDPs were subjected to single load-to-failure (SLF) testing at a crosshead speed (1 mm/min). Lifetime analysis was conducted to determine the probability of survival, and fractographic analysis was performed.

RESULTS

Significant differences were observed among the studied groups for SLF with the highest characteristic strength values observed for PFZ (2154 N), followed by 1905.47 N for CVZ and 1679.56 N for FRC. The probability of survival for 100,000 cycles at 500 N was the highest for FRC (98%) and CVZ (100%) and was significantly lower for PFZ (88%). Different fracture patterns were observed in the fractography.

CONCLUSIONS

In fatigue testing, which simulates masticatory function better than static tests, a higher probability of survival was observed for FRC and CVZ than for PFZ. Framework fractures were not observed only for the FRC group, indicating that chairside repair with the addition of indirect composite could be performed for continued function.

The incisal foramen as a means of insertion for one of three ultra-short implants to support a prosthesis for a severely atrophic maxilla - A short-term report

As a continuation of our prospective cohort study for a total of 18 patients with 72 implants in severely atrophic maxillae corresponding to Cawood and Howell class V and VI (1988) [1] with four 4.0 × 5.0 mm ultrashort locking taper implants Ewers et al., 2018 [2], we now present a prospective cohort study with a total of 9 patients. The special feature of this newly modified study is the reduction of the number of implants to only three 4.0 × 5.0 mm or 4.5 × 6.0 mm or 5.0 × 6.0 mm calcium phosphate-coated Bicon Integra CP implants. Reducing the number of implants is possible by inserting the middle implant into the incisal foramen and the nasopalatine canal. All patients were restored with metal-free prostheses made of a glass fiber-reinforced hybrid resin material. Neither were any implants lost during the observation period, nor did any patient experience any sensory alteration due to the placement of an implant into the nasopalatine canal. Three implants were sufficient in all patients to stabilize their 12-unit prosthesis.