Bradley S. McAllister

Peri-implant mucositis and peri-implantitis: A current understanding of their diagnoses and clinical implications

Theuseofdental implantshas revolutionized the treatment of partially and fully edentulous patients today. Implants have becomea treatment approach formanaging a broad range of clinical dilemmas due to their high level of predictability and their ability to be used for a wide variety of treatment options. While in many cases dental implants have been reported to achieve long-term success, they are not immune fromcomplications associated with improper treatment planning, surgical and prosthetic execution, material failure, and maintenance. Included in the latter are the biologic complications of peri-implant mucositis and peri-implantitis, inflammatory conditions in the soft and hard tissues at dental implants. It is the purpose of this paper to review the current knowledge concerning peri-implant mucositis and peri-implantitis to aid clinicians in their diagnoses and prevention. It is recognized that new information will continue to emerge, and as such, this document represents a dynamic endeavor that will evolve and require further expansion and reevaluation.

Platelet-Derived Growth Factor Promotes Periodontal Regeneration in Localized Osseous Defects: 36-Month Extension Results From a Randomized, Controlled, Double-Masked Clinical Trial

BACKGROUND Recombinant human platelet-derived growth factor (rhPDGF) is safe and effective for the treatment of periodontal defects in short-term studies up to 6 months in duration. We now provide results from a 36-month extension study of a multicenter, randomized, controlled clinical trial evaluating the effect and long-term stability of PDGF-BB treatment in patients with localized severe periodontal osseous defects. METHODS A total of 135 participants were enrolled from six clinical centers for an extension trial. Eighty-three individuals completed the study at 36 months and were included in the analysis. The study investigated the local application of β-tricalcium phosphate scaffold matrix with or without two different dose levels of PDGF (0.3 or 1.0 mg/mL PDGF-BB) in patients possessing one localized periodontal osseous defect. Composite analysis for clinical and radiographic evidence of treatment success was defined as percentage of cases with clinical attachment level (CAL) ≥2.7 mm and linear bone growth (LBG) ≥1.1 mm. RESULTS The participants exceeding this composite outcome benchmark in the 0.3 mg/mL rhPDGF-BB group went from 62.2% at 12 months, 75.9% at 24 months, to 87.0% at 36 months compared with 39.5%, 48.3%, and 53.8%, respectively, in the scaffold control group at these same time points (P <0.05). Although there were no significant increases in CAL and LBG at 36 months among all groups, there were continued increases in CAL gain, LBG, and percentage bone fill over time, suggesting overall stability of the regenerative response. CONCLUSION PDGF-BB in a synthetic scaffold matrix promotes long-term stable clinical and radiographic improvements as measured by composite outcomes for CAL gain and LBG for patients possessing localized periodontal defects ( ClinicalTrials.gov no. CT01530126).

Histologic Evaluation of a Stem Cell–Based Sinus‐Augmentation Procedure

BACKGROUND Predictability has been demonstrated for the long-term success of dental implants placed simultaneously with or after a sinus-augmentation procedure. However, the time required to obtain optimal bone formation can be from 6 to 9 months or longer with grafting materials other than autogenous bone. For this reason, there is interest in a surgical technique that does not require the harvest of autogenous bone but still results in sufficient bone formation within a relatively short time frame. METHODS The purpose of this case series was to evaluate the bone formation following sinus-augmentation procedures using an allograft cellular bone matrix containing native mesenchymal stem cells. Biopsy and histologic evaluation were performed after approximately 4 months of healing. RESULTS Histomorphometric analysis revealed an average vital bone content of 33% (range, 22% to 40%) and an average residual graft content of 6% (range, 3% to 7%) for the five cases reported that had an average healing period of 4.1 months (range, 3 to 4.75 months). CONCLUSION The high percentage of vital bone content, after a relatively short healing phase, may encourage a more rapid initiation of implant placement or restoration when a cellular grafting approach is considered.

Emerging Regenerative Approaches for Periodontal Reconstruction: A Consensus Report From the AAP Regeneration Workshop

BACKGROUND Historically, periodontal regeneration has focused predominantly on bone substitutes and/or barrier membrane application to provide for defect fill and/or selected cell repopulation of the lesion. More recently, a number of technologies have evolved that can be viewed as emerging therapeutic approaches for periodontal regeneration, and these technologies were considered in the review paper and by the consensus group. The goal of this consensus report on emerging regenerative approaches for periodontal hard and soft tissue reconstruction was to develop a consensus document based on the accompanying review paper and on additional materials submitted before and at the consensus group session. METHODS The review paper was sent to all the consensus group participants in advance of the consensus conference. In addition and also before the conference, individual consensus group members submitted additional material for consideration by the group. At the conference, each consensus group participant introduced themselves and provided disclosure of any potential conflicts of interest. The review paper was briefly presented by two of the authors and discussed by the consensus group. A discussion of each of the following topics then occurred based on the content of the review: a general summary of the topic, implications for patient-reported outcomes, and suggested research priorities for the future. As each topic was discussed based on the review article, supplemental information was then added that the consensus group agreed on. Last, an updated reference list was created. RESULTS The application of protein and peptide therapy, cell-based therapy, genetic therapy, application of scaffolds, bone anabolics, and lasers were found to be emerging technologies for periodontal regeneration. Other approaches included the following: 1) therapies directed at the resolution of inflammation; 2) therapies that took into account the influence of the microbiome; 3) therapies involving the local regulation of phosphate and pyrophosphate metabolism; and 4) approaches directed at harnessing current therapies used for other purposes. The results indicate that, with most emerging technologies, the specific mechanisms of action are not well understood nor are the specific target cells identified. Patient-related outcomes were typically not addressed in the literature. Numerous recommendations can be made for future research priorities for both basic science and clinical application of emerging therapies. The need to emphasize the importance of regeneration of a functional periodontal organ system was noted. The predictability and efficacy of outcomes, as well as safety concerns and the cost-to-benefit ratio were also identified as key factors for emerging technologies. CONCLUSIONS A number of technologies appear viable as emerging regenerative approaches for periodontal hard and soft tissue regeneration and are expanding the potential of reconstructing the entire periodontal organ system. The cost-to-benefit ratio and safety issues are important considerations for any new emerging therapies. Clinical Recommendation: At this time, there is insufficient evidence on emerging periodontal regenerative technologies to warrant definitive clinical recommendations.

American Academy of Periodontology Best Evidence Consensus Statement on Selected Oral Applications for Cone-Beam Computed Tomography

BACKGROUND The American Academy of Periodontology (AAP) recently embarked on a Best Evidence Consensus (BEC) model of scientific inquiry to address questions of clinical importance in periodontology for which there is insufficient evidence to arrive at a definitive conclusion. This review addresses oral indications for use of cone-beam computed tomography (CBCT). METHODS To develop the BEC, the AAP convened a panel of experts with knowledge of CBCT and substantial experience in applying CBCT to a broad range of clinical scenarios that involve critical structures in the oral cavity. The panel examined a clinical scenario or treatment decision that would likely benefit from additional evidence and interpretation of evidence, performed a systematic review on the individual, debated the merits of published data and experiential information, developed a consensus report, and provided a clinical bottom line based on the best evidence available. RESULTS This BEC addressed the potential value and limitations of CBCT relative to specific applications in the management of patients requiring or being considered for the following clinical therapies: 1) placement of dental implants; 2) interdisciplinary dentofacial therapy involving orthodontic tooth movement in the management of malocclusion with associated risk on the supporting periodontal tissues (namely, dentoalveolar bone); and 3) management of periodontitis. CONCLUSION For each specific question addressed, there is a critical mass of evidence, but insufficient evidence to support broad conclusions or definitive clinical practice guidelines.

Evaluation of a variable-thread tapered implant in extraction sites with immediate temporization: a 3-year multicenter clinical study.

BACKGROUND The purpose of this clinical study is to evaluate the radiographic bone remodeling, survival rate, and soft tissue health surrounding a variable-thread tapered implant immediately placed in extraction sites. METHODS Sixty implants were placed in 55 patients at six centers according to a predetermined protocol. All implants were placed in extraction sockets and were subjected to immediate temporization and function. Definitive prostheses (58 single crowns and one two-unit fixed bridge) were placed within the first year. Clinical and radiographic examinations were performed at implant placement and after 3, 6, 12, 24, and 36 months. Measurements of implant stability, papilla index, plaque, peri-implant mucosa, and marginal bone levels were recorded at each visit. RESULTS Thirty-five implants were evaluated at both implant insertion and 3-year follow-up. Bone levels were observed at 6 months after surgery and yearly intervals thereafter and remained stable throughout the study. There was a slight decrease in mean bone level from -0.68 mm at implant insertion to -0.93 mm at the 6-month recall and then an increase of bone to -0.53 mm from the reference point at the 2-year follow-up (an average increase of 0.15 mm from implant insertion). Bone levels remained steady between the 2-year recall and the 3-year recall. Papilla scores increased significantly (P <0.001; Wilcoxon signed-rank test) from insertion to the 3-year follow-up, with most of the increase occurring during the first year. Patient assessments of function, esthetics, feel of implant, speech, and self-esteem also showed significant improvement over the course of the study. CONCLUSIONS The results, over 36 months, indicate that the variable-thread tapered implant can be used safely and effectively under demanding conditions as an immediate postextraction tooth replacement. Bone remodeling remained stable with a slight increase, and patients expressed high levels of satisfaction with the restorative results over the course of the study.

Signal Transduction Mechanisms in Mesenchymal Cells

Mesenchymal cells are continually stimulated by a wide spectrum of biological mediators. These mediators bind to receptors on the cell surface and initiate a cascade of signaling events. The initial signal transduction pathways known to be stimulated in mesenchymal cells included phospholipase C, phospholipase D, phospholipase A2, adenylate cyclase, receptor tyrosine kinases, and receptor serine/threonine kinases. These pathways are reviewed and specific applications for therapeutic intervention in wound healing and regenerative therapy in the periodontium are discussed.

Commentary: Cone-Beam Computed Tomography: An Essential Technology for Management of Complex Periodontal and Implant Cases

T he advent of cone-beam computed tomography (CBCT) has become one of themost useful advances in periodontology. CBCT has the potential to streamline clinical workflow; enhance the periodontist’s skills in diagnosis and complex treatment planning; hone surgical anatomic expertise; and improve outcomes in specific implant and periodontal cases. Periodontists are, and should continue to be, the leaders in applications of emerging technologies like CBCT, which enjoy widespread use but lack sufficient research that provides traditional evidence-based guidance to the clinician. The American Academy of Periodontology (AAP) recognizes the importance of continued development in these new fields as well as the need for clinical direction in the absence of definitive data. Consequently, the AAP used a model of scientific inquiry called ‘‘best evidence consensus’’ (BEC), which is grounded by best available current published evidence, with consensus expert opinion to guide reasonable additional uses in selected clinical scenarios. Two BEC meetings were conducted in 2017—one on CBCT and another on lasers. For each BEC topic, specific clinically relevant questions were developed, systematic reviews were written, and a panel of experts was convened to review findings and provide expert opinion to guide clinicians on ‘‘best practice’’ use of these evolving technologies. This issue of the Journal of Periodontology contains proceedings of the BEC on CBCT. Research on the use of CBCT continues to be published; however, the significant growth rate of this technology over the past 15 years is likely an indication that it may be critical to our practices. To maintain a leadership role in the application of CBCT technology, periodontists must remain abreast of continued research regarding its clinical benefits and limitations. The decision to integrate CBCT into practice is not to be taken lightly. Understanding what it can accomplish and its limitations is critical. Implementation can be costly in terms of the equipment purchase and the required time investment for clinician and staff to become properly trained, not only in the nuances of the machines, but also in critical decision making as to when taking a CBCT is appropriate. The BEC papers on CBCT technology in this issue are excellent references for new clinicians considering a CBCT unit and for seasoned clinicians evaluating how their current protocols align with the currently accepted state of the art. While implant reconstruction represents its most common use, CBCT has become an important tool in the armamentarium of many specialists. Our continued team approach to comprehensive patient treatment with general dentists, oral and maxillofacial radiologists, and other specialists will allow us to increase our knowledge of clinical indications for CBCT. The AAP Best Evidence Consensus papers1-4 reviewed the current and diverse ways CBCT applies to patient care, and experts provided their opinions on the following specific clinical questions regarding CBCT use: Question 1. Should CBCT imaging replace twodimensional (2D) radiographic analysis of regional anatomy in the surgical management of patients requiring dental implants? To address this question, three major areas were identified and reviewed. Indications included CBCT use for: 1) diagnosis and treatment outcome assessment; 2) implant treatment planning; and 3) anatomic characterization. There is considerable literature that supports CBCT use in all three areas. The clinical bottom line determined by the expert panel was that CBCT has diverse applications for dental implant therapy and should be used as an adjunct to 2D radiology when the specific benefits to the patient

Accuracy and Reproducibility of Radiographic Images for Assessing Crestal Bone Height of Implants Using the Precision Implant X-ray Locator (PIXRL) Device

PURPOSE Assessment of crestal bone levels around implants is essential to monitor success and health. This is best accomplished with intraoral radiographs exposed at 90 degrees to the long axis of the implant, but this can be challenging to achieve clinically. Radiographic paralleling devices produce orthogonal radiographs but traditionally have required access to the implant body for each exposure. This study was conducted to determine if use of the Precision Implant X-ray Locator (PIXRL), a radiographic paralleling device that indexes the implant at the time of surgical placement, can produce orthogonal radiographs of dental implants more accurately than traditional radiologic techniques for assessing crestal bone levels. MATERIALS AND METHODS Three dental implants were inserted in dry human skulls in supracrestal positions to simulate crestal bone loss (maxillary right first premolar [site 14], maxillary right central incisor [site 11], and mandibular left second premolar [site 35]). The implants were masked with a soft tissue moulage and restored with provisional restorations. Four dental assistants exposed six radiographs using their usual and customary technique and six using the PIXRL device for each implant. A single examiner measured crestal bone levels on the radiographs relative to the implant platform shoulder on the mesial and distal of each implant. Recorded measurements were compared to the known values. Statistical analysis was completed using a generalized linear regression model to analyze the differences, and post-hoc comparisons with pairwise adjustment were applied. RESULTS The images produced using the PIXRL device were more accurate overall compared to traditional techniques and were also more consistent. The greater degree of accuracy was statistically significant for all sites with the exception of the mesial measurements of the implant at site 11. CONCLUSION This study demonstrates that the use of the PIXRL device can assist clinicians in obtaining more accurate orthogonal radiographs for assessing crestal bone height and would be a useful tool for researchers utilizing radiographic imaging of implants as a longitudinal measure of implant success and stability.

Implant Site Development Using Ti-Mesh and Cellular Allograft in the Esthetic Zone for Restorative-Driven Implant Placement: A Case Report.

This article presents a case report of implant site development in a healthy, nonsmoking 62-year-old man using titanium mesh (Ti-mesh) in conjunction with human cellular allograft for ridge augmentation of a type 4 alveolar ridge defect. The patient presented initially with a severely periodontally abscessed maxillary right central incisor probing to the apex. The tooth was extracted, and after 8 weeks a bone reconstructive procedure was completed using a well-stabilized Ti-mesh and cellular allograft that was covered with a quickly resorbing collagen matrix. After 7 months of undisturbed healing, cone beam computed tomographic evaluation demonstrated a horizontal bone increase of 7 mm and a vertical bone increase of 2.3 mm. This case report demonstrates the benefits of predictable regenerative space maintenance using Ti-mesh in conjunction with a cellular allograft to allow for prosthetically driven implant placement in the esthetic zone.