Contemporary concepts on periodontal complications from prosthetic and restorative therapies.

The clinical outcome of every prosthetic and restorative procedure depends on the maintenance of a healthy periodontium. It is, therefore, important that the prosthodontist and restorative dentist cause no harm or permanent damage to the underlying hard and soft tissues when performing clinical procedures necessary to carry out the planned treatment. Several factors involved in these procedures have been described to have an impact on gingival health. For the present article, a selection of four of these factors are presented with the goal of evaluating the current trends and their influence on periodontal structures: (1) tooth preparation configuration and apical extension, (2) gingival tissue sulcular expansion/retraction, (3) prosthetic contours, and (4) prosthesis marginal adaptation and the consequences of excess cement remnants. Based on the available scientific evidence and clinical experience, recommendations for the practitioner are given.

Digital workflow in implant prosthodontics: The critical aspects for reliable accuracy.

INTRODUCTION: This paper is a comprehensive treaty about the variables that influence the transfer of the position of an implant to the laboratory when using a digital workflow. OBJECTIVE: The aim is to provide operators and manufacturers with a guide on how to improve certain aspects of the digital workflow specific to the fabrication of implant-supported restorations. OVERVIEW: It addresses intraoral scanning issues and CAD software issues. In the former, the variables that play a part in the quality of the scan file are investigated: the implant scan body, the IOS and the operator. For the latter, instead, the focus is on those aspects that still today may create inaccuracies in the workflow and in the final product being fabricated: the identification of the specific implant placed in the patient and the generation of a virtual model with the representation of that implant platform correctly positioned in the three dimensions of space. Suggestions and recommendations are given to improve the control on the quality of the digital workflow's output. CONCLUSION: In a digital workflow for the fabrication of an implant-supported restoration, the selection and use of the implant scan body, the use of an effective scan strategy and the appropriateness of the best fit function in the CAD software, that is, the procedure of superimposing the library of geometric shapes of the ISB linked to the implant with the shape acquired intraorally, are variables that can influence the positional precision of the FDP. CLINICAL SIGNIFICANCE: Fully understanding the importance of the information enclosed in the ISBs themselves can be crucial in the digital workflow. A proper ISB's selection, a correct scan of the ISB's shape and an accurate CAD superimposition of the ISB's library can lead the clinician to reduce the variables that affect the final result in daily practice.

Managing Patient Treatment Through Deming's PDCA Cycle: A Standardized Approach in Phases that Adds Value to Dental Care.

This essay is an expert opinion by 3 clinicians who feel the need for a clear phased approach capable of integrating all dental therapies for the care of patients suffering from multiple pathologies of the oral cavity. At the moment, the only guidelines available when treating interdisciplinary cases, i.e., patients with multiple overlapping pathologies (carious disease, periodontal disease, malocclusion, incongruous restorations, etc.), are those describing the proper sequence of periodontal therapy. The authors take inspiration from a method developed in the manufacturing world, the so called "lean management", and its tools to outline the sequence of therapy phases and the correct placement of the various activities within these phases. In the "lean healthcare', it is the patient at the center of the attention and it is him/her who 'pulls' the process with his/her health as the main value.

Working Models in the Digital Workflow: Are They Reliable?

PURPOSE: This position paper summarizes all relevant aspects of the use of working models derived from digital data in digital and hybrid workflows, aiming to (1) provide the reader with a comprehensive review of the types of models that currently can be produced from a digital file created by an intraoral scanner (IOS); (2) critically analyze issues that may undermine or compromise their reliability when requested for the fabrication of both tooth-borne and implant-supported fixed dental prostheses (FDPs); and (3) indicate the procedures to be implemented in order to overcome these issues and produce satisfactory restorations. MATERIALS AND METHODS: By way of a thorough literature review, the authors highlight the critical issues of milled and 3D-printed models, solid and alveolar, explaining the differences in terms of accuracy and reliability. RESULTS AND CONCLUSIONS: By describing the peculiarities of models with prepared natural teeth and those incorporating metal implant analogs, the clinical indications for their use are given while proposing the strategies that can be adopted to avoid errors during fabrication or to overcome inaccuracies.

Internal vs. external connections for abutments/reconstructions: a systematic review.

OBJECTIVES: The objectives of the review were (1) to evaluate the accuracy of implant-level impressions in cases with internal and external connection abutments/reconstructions, and (2) to evaluate the incidence of technical complications of internal and external connection metal- or zirconia-based abutments and single-implant reconstructions. MATERIALS AND METHODS: A MEDLINE electronic search was conducted to identify English language publications in dental journals related to each of the two topics by inserting the appropriate keywords. These electronic searches were complemented by a hand search of the January 2009 to January 2012 issues of the following journals: Clinical Oral Implants Research, The Journal of Prosthetic Dentistry, The International Journal of Prosthodontics, The International Journal of Periodontics and Restorative Dentistry, The International Journal of Oral Maxillofacial Implants, Clinical Implant Dentistry and Related Research. RESULTS: Seven in vitro studies were included in the review to evaluate the accuracy of implant-level accuracy. No clinical study was found. There was no study that directly compared the influence of internal and external implant connections for abutments/reconstructions on the accuracy of implant-level impressions. All in vitro studies reported separately on the two connection designs and they did not use same protocol and, therefore, the data could not be compared. Fourteen clinical studies on metal-based abutments/reconstructions and five clinical studies on zirconia-based abutments/reconstructions satisfied the inclusion criteria and, therefore, were included in the review to evaluate the incidence of technical complications. The most frequent mechanical complication found in both implant connection design when employing metal abutments/reconstructions was screw loosening. CONCLUSIONS: Implant-level impression accuracy may be influenced by a number of variables (implant connection type, connection design, disparallelism between multiple implants, impression material and technique employed). Implant divergence appears to affect negatively impression accuracy when using internal connection implants. Based on the sparse literature evaluating the incidence of technical complications of metal or zirconia abutments/reconstructions, it was concluded that: The incidence of fracture of metal-based and zirconia-based abutments and that of abutment screws does not seem to be influenced by the type of connection. Loosening of abutment screws was the most frequently occurring technical complication. The type of connection seems to have an influence on the incidence of the screw loosening: more loose screws were reported for externally connected implant systems for both types of materials. However, proper preload may decrease the incidence of such a complication.

A simplified method to develop an interdisciplinary treatment plan: an esthetically and functionally driven approach in three steps.

Many clinicians are unsure of how to develop a comprehensive plan of treatment for patients who present with multiple problems and pathologies. In order to efficiently plan appropriate treatment for such complex patient cases, the clinician needs to either have or develop the necessary knowledge of evidence-based information on the predictability of available clinical procedures. The clinician also needs to understand the correct sequence in which such treatment is applied, and perfect the skills required for carrying out that treatment. Since most clinicians have not acquired all the knowledge and skills necessary for this task, an interdisciplinary approach to treatment is typically required. This article provides a practical step-by-step approach to planning comprehensive interdisciplinary treatment focused primarily on the teeth as they relate to each other and to the structures that surround them. The approach is based on the answers to six questions that are grouped into three steps: 1) evaluation of the teeth relative to the face and lips; 2) assessment of anterior tooth dimensions; and 3) analysis of the anteroposterior and maxillomandibular relationships. The information obtained must then be related to the patient's skeletal framework, periodontal status, caries susceptibility, and biomechanical risk assessment in order to formulate a clear and complete plan of treatment.

Clinical Considerations on Strategies That Avoid Multiple Connections and Disconnections of Implant Abutments.

Typically, healing or temporary abutments are connected and disconnected several times between implant placement and definitive restoration delivery, and soft tissue disruption occurs each time the abutment is disconnected and reconnected. This histologic event is supposed to cause bone resorption around the implant after second-stage surgery. To minimize this clinical scenario, immediately placing and never removing a definitive abutment the day of implant insertion (one-stage protocol) or at second-stage surgery in cases of submerged implants (two-stage protocol) was suggested. This paper details the prosthetic protocol and presents strategies and rationales for placing a definitive abutment the day of implant insertion or at second-stage surgery with cement- and screw-retained restorations. This protocol seems to be an efficient strategy to preserve peri-implant hard and soft tissues. However, positive outcomes in peri-implant bone and soft level changes should be viewed with caution, as their clinical significance is still uncertain.

The Influence of Implant Neck Features and Abutment Diameter on Hard and Soft Tissues Around Single Implants Placed in Healed Ridges: Clinical Criteria for Selection.

The clinician's selection of an implant system is influenced by many variables. Ideally, the decision should be based on scientific evidence, but often these decisions are based on economic considerations or influenced by the experience of a trusted peer. The purpose of this paper is to describe the influence of implant neck features (shape and surface) and abutment connection (diameter that matches or is smaller than the implant's platform) on hard and soft tissues around single-tooth implants placed into healed ridges with adequate hard and soft tissue thickness. In an effort to reduce the number of variables, only two-piece implants fully placed at bone level or beneath were taken into consideration. The goal is to provide additional guidance for clinicians on the decision-making and implant-selection processes.

Internal- vs External-Connection Single Implants: A Retrospective Study in an Italian Population Treated by Certified Prosthodontists.

PURPOSE: The design of an implant connection that allows prosthetic suprastructures to be attached to implants has long been debated in the dental literature. The goal of this retrospective study was to evaluate the 5-year clinical results for a large number of single implants restored by certified prosthodontists in an attempt to establish whether different clinical outcomes could be detected for external- or internal-connection implants. MATERIALS AND METHODS: All single implants with internal or external connections inserted in 27 private dental practices from January 1, 2003 to December 31, 2007 were evaluated. An initial statistical analysis was performed to describe the sample population at baseline and then to compare the two types of implant-abutment connection configurations and their clinical outcomes. All data were statistically analyzed with STATA12 (StataCorp). RESULTS: Twenty-eight of the 85 active members of the Italian Academy of Prosthetic Dentistry (AIOP) participated in this study. The sample included 1,159 patients and 2,010 implants. Of the implants, 75 were dropped because there was no information about follow-up. Of the remaining implants, 1,431 (74.0%) were followed for at least 5 years, and 332 implants (17.2%) were followed for more than 8 years. Nearly 99% (98.9%) of the implants survived. The difference between the survival frequencies of the two types of implant-abutment connection configurations was not significant for each negative event (log-rank test, P > .05). There was no difference between the two types of implants regarding restoration fracture, implant screw loosening, and peri-implant disease. CONCLUSION: Within the limitations of this study, it can be suggested that there is no difference in clinical outcomes of single restorations joined to internal- or external-connection implants.

Influence of the 3-D bone-to-implant relationship on esthetics.

There are biologic limits of the soft tissue dimension around implants; therefore, the limiting factor for the esthetic result of implant therapy is the bone level at the implant site. Clinicians must focus on the 3-D bone-to-implant relationship to establish the basis for an ideal and harmonic soft tissue situation that is stable over a long period. In some situations, missing bone is a limiting factor for esthetics; in others, it is possible to regenerate new bone around implants. As a certain amount of bone resorption occurs around implants as soon as the implant is in contact with the oral environment, the distance between an implant and adjacent tooth, as well as the distance between two implants, is as important as the bone volume on the buccal side of the implant head and in the papillary area, especially for the long-term result. This article discusses the 3-D bone-to-implant relationship and its influence on soft tissue esthetics around implants.

Eleven-Year Retrospective Survival Study of 275 Veneered Lithium Disilicate Single Crowns.

The aim of the present clinical retrospective study was to evaluate the long-term survival and clinical performance of veneered lithium disilicate single restorations in anterior and posterior areas after up to 11 years. Following a rigid protocol, 275 lithium disilicate single crowns (35 IPS Empress II and 240 e.max Press) were cemented over 11 years, in 106 patients, using an adhesive technique; of these 106 were anterior (38.5%) and 169 posterior (61.5%) teeth. Teeth receiving endodontic therapy and composite reconstruction (50%) and teeth with preexisting metalceramic crowns, called prosthetic retreatments (PR; 65%), were included as well. Of the 106 patients enrolled in the study, 25 (23.5%) were diagnosed with bruxism habits, and 7 of these patients (6.6% of all patients) received full-mouth single lithium disilicate restorations (FMR). The exclusion criteria for this retrospective clinical study were: monolithic lithium disilicate crowns, teeth with cast post and cores, implant-supported all-ceramic crowns, active periodontitis, and/or poor oral hygiene. Clinical reevaluation was performed by the clinicians who prepared and luted them during maintenance appointments between January 2012 and October 2013. Number of restoration failures and characteristics of failures were recorded. Marginal adaptation and marginal discoloration were evaluated based on the Cvar-Ryge criteria. The overall cumulative survival rate was 98.2%. The failures recorded were the result of either mechanical failure or debonding. Five crowns failed mechanically-three because of chipping and two because of core fracture-and were replaced. None of the failed crowns was associated with the bruxers with FMR. A total of 15 crowns debonded (5.5% of all crowns); however, 11 belonged to the same patient who had endodontically treated and reconstructed abutments. In this retrospective clinical evaluation of up to 132 months, veneered lithium disilicate single crowns had a low failure rate.

Efficacy of two site-development procedures for implants in the maxillary esthetic region: a systematic review.

PURPOSE: The purpose of this systematic review was to identify studies in which either orthodontic extrusion or bone grafting was used prior to single implant placement in the maxillary esthetic zone and to compare the biologic, functional, and esthetic outcomes of these two approaches. MATERIALS AND METHODS: An electronic MEDLINE search was conducted by three independent reviewers to identify English-language articles, published in dental journals between January 1992 and August 2013, reporting on single-implant site development accomplished by orthodontic forced eruption of nonrestorable teeth or by bone grafting procedures. The search terms were categorized into four groups comprising a PICO (problem, intervention, comparison, outcome) question. Supplementary manual searches of published full-text articles and related reviews were also performed. RESULTS: The initial database search produced 301 relevant titles. After careful examination and discussion, 32 studies were selected for inclusion. No study directly comparing the two implant site-development methods was identified. The observation periods of the available studies were either short or not stated. CONCLUSION: There is a substantial lack of evidence to determine which method for implant site development is better. Definitive conclusions cannot be drawn, since no clinical trials have directly compared these two methods. All included studies reported separately on the two implant site-development methods and used different protocols. According to the literature reviewed, it seems that both methods of implant site development are effective and neither method is superior. Multicenter studies and randomized clinical trials should be performed to evaluate the efficacy of these two methods.

A new classification system for all-ceramic and ceramic-like restorative materials.

Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

Clinical considerations and rationale for the use of simplified instrumentation in occlusal rehabilitation. Part 1: Mounting of the models on the articulator.

The development of an occlusal scheme with an appropriate number and location of occlusal contacts is of the utmost importance for the long-term success of any prosthetic rehabilitation. This, however, can be a time-consuming procedure. To avoid undue mistakes, a high degree of competence must be demonstrated by both the clinician and the technician. Especially when performing extensive rehabilitations, many operators believe that to have optimum control of the occlusal variables, it is necessary to employ rather sophisticated instruments and complicated procedures. This article presents a rationale for an approach that uses a simplified but sound instrumentation in the clinical and laboratory steps necessary to produce a successful prosthesis. In part 1, the registration of the spatial position of a patient's maxillary and mandibular arches is described.

Clinical considerations and rationale for the use of simplified instrumentation in occlusal rehabilitation. Part 2: setting of the articulator and occlusal optimization.

In fabricating a prosthetic rehabilitation, whether it consists of just a single crown or a complete-mouth reconstruction, one of the main aims of the clinician is to simplify the procedures and reduce the time necessary to integrate it into the mouth of the patient This article completes the description of the rationale behind the selection of semiadjustable articulators and of a way to transfer to the laboratory technician valuable information that, in the case of extensive rehabilitations, will make occlusal optimization more error free.

Aesthetic functional area protection concept for prevention of ceramic chipping with zirconia frameworks.

Chipping of the ceramic veneer is reported as a frequent occurrence when using zirconia-based fixed dental prostheses (FDPs). One possible cause of this complication is the inadequate support of the veneering ceramic by the zirconia substructure. In this article, early clinical observations from patients treated with 96 zirconia-based ceramic single- and multiple-unit FDPs on natural teeth and implants are presented. The FDPs were fabricated according to the aesthetic functional area protection concept of framework design for the prevention of ceramic chipping.