The Effect of Implant-Induced Artifacts on Interpreting Adjacent Bone Structures on Cone-Beam Computed Tomography Scans.

INTRODUCTION: Cone-beam computed tomography (CBCT) imaging can be used to visualize anatomical structures before implant placement. The aim of this study is to evaluate the impact of implant artifacts on the accuracy of measuring periimplant bone dimensions. MATERIALS AND METHODS: Nineteen implants were placed into 9 fresh, frozen cadavers. A CBCT scan was taken, the implants were removed, and a second scan was taken. Implant dimensions and periimplant bone measurements were calculated. The mean differences were compared with paired t tests. Pearson's correlation coefficients were calculated for bone thickness measurements. DISCUSSION: No significant differences were found between the implant dimension or bone thickness measurements on each scan. Bone thickness at the implant platform and apex were significantly correlated (P < 0.001). CONCLUSION: The presence of dental implants did not impact the accuracy of cone-beam computed tomography (CBCT) measurements of bone thickness by metallic artifacts.

Evaluation of Single Tooth Loss to Maxillary Sinus and Surrounding Bone Anatomy With Cone-Beam Computed Tomography: A Multicenter Study.

BACKGROUND: Posterior maxillary tooth loss may complicate the implant treatment due to the alterations in alveolar anatomy and maxillary sinus pneumatization. This study aimed to comprehensively examine the anatomical structure of this region from cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: The posterior maxilla regions with single tooth loss were analyzed by dividing the variables into 3 subgroups from images of 597 patients chosen from 1160 CBCTs. Variables associated with sinus membrane (SM), sinus dimensions, ostium, septa, sinus neighborhood, alveolar bone height (ABH) and width (RW), posterior superior alveolar artery (PSAA), and adjacent roots were evaluated. RESULTS: The majority of the patients demonstrated 0 to 5 mm membrane thickness. Irregular SM thickening was lower for female patients. While females showed higher number of narrow sinus, males had higher RW than females. Sinus augmentation classification showed negative correlation with ABH, root-tip sinus floor and edentulous site classification. Posterior septa height was correlated with number of septa and ABH. PSAA diameter and location were also correlated between each other. CONCLUSION: The present results define formation of a sinus space with 11 mm coronal and 16 mm apical width after single tooth loss. A flat or semispherical thickening around 4 mm is usual in most cases with 51% possibility of anterior septum existence. A ridge anatomy, around 7.5 mm ABH and 7.2 to 9.3 RW from coronal to apical, complements this anatomy. Further studies are needed to clarify the reasons behind the SM and crestal anatomy variations between genders.

Accuracy of Cone Beam Computed Tomography Grayscale Density in Determining Bone Architecture in the Posterior Mandible: An In Vivo Study with Microcomputed Tomography Validation.

PURPOSE: The aim of this study was to analyze the reliability of cone beam computed tomography (CBCT) in assessing the grayscale density (GSD) of bone by comparing it with microcomputed tomography (µ-CT) data. MATERIALS AND METHODS: A total of 50 subjects with lost mandibular molars were included in the study. To assess the bone GSD, a previously fabricated template made of acrylic resin with a 2-mm-diameter metal rod was positioned, and CBCT was performed. The bone biopsies for µ-CT analysis were then obtained during implant surgery. The relationship between GSD assessed by CBCT and data from µ-CT analysis was studied using Spearman's rank correlation. RESULTS: A total of 38 biopsies were available for µ-CT analysis. Positive correlations were identified between GSD and bone volumetric fraction (BV/TV) (r = 0.835, P < .001), bone volume (BV) (r = 0.353, P = .030), trabecular spacing (Tb.Sp) (r = -0.535, P = .001), and mean total volume (TV) (r = 0.470, P = .003). There was a clear positive linear correlation between normal values of GSD (< 700) and BV (r = 0.545). CONCLUSION: This study demonstrated the correlation between GSD assessed by CBCT and bone density assessed by µ-CT in the posterior mandible. For areas of typical bone density, there seems to be a positive linear correlation between GSD assessed by CBCT and bone density assessed by µ-CT.

Influence of Posterior Mandibular Dimensions on Alveolar Bone Microarchitecture.

PURPOSE: The aim of this study was to investigate the influence of posterior mandibular dimensions (height and width at various levels) on alveolar bone microarchitecture using microcomputed tomography (micro-CT). MATERIALS AND METHODS: Partially edentulous subjects with one missing molar were included in the study. A bone core biopsy was performed at the site of planned implant surgery. For each patient, alveolar morphologic and architectural characteristics were analyzed using cone beam computed tomography (CBCT) and micro-CT imaging. Two parameters for height (apicocoronal residual height [RH] and residual ridge from inferior alveolar canal [RHN]) and three for buccolingual width (residual width at 5 mm [RW1], at 10 mm [RW2], and at 15 mm [RW3]) were determined using CBCT. Additionally, 10 parameters were obtained from micro-CT to determine microarchitecture. Pearson product-moment correlation coefficients were calculated to examine the correlation between the morphologic and microarchitectural variables. RESULTS: Significant positive correlations (P < .05) were found between RH and bone volumetric fraction (BV/TV) (rs = 0.34) and trabecular thickness (Tb.Th) (rs = 0.45). A significant negative correlation was found between RH and the bone-specific surface (BS/BV) (rs = -0.34). A strong significant negative correlation was found between trabecular spacing (Tb.Sp) and RW1 (rs = -0.42). None of the other variables reached statistical significance. CONCLUSION: Posterior mandibular dimensions may affect bony architectural characteristics.

Flap Designs for Flap Advancement During Implant Therapy: A Systematic Review.

PURPOSE: Guided bone regeneration (GBR) procedures allow ridge augmentation before or at time of implant placement. GBR outcomes rely on primary passive tension-free wound closure, which may be achieved by a variety of flap designs and surgical procedures. A comprehensive literature review of flap design and management is provided, including material types, incision design, reflection, releasing, and suturing techniques. MATERIALS AND METHODS: Two reviewers completed a literature search using the PubMed database and a manual search of relevant journals. Relevant articles from January 1990 to September 2015 published in the English language were considered. RESULTS: A variety of flap designs aim to achieve primary passive closure during GBR were introduced. To facilitate case selection and treatment planning, flap designs have been categorized based on their ability to achieve minor (<3 mm), moderate (3-6 mm), and major (≥7 mm) degrees of flap advancement. CONCLUSIONS: Techniques such as vertical releasing incisions, periosteal releasing incisions, and split-thickness flaps may be used alone or combined to achieve passivity during GBR. GBR complications may be prevented by imaging and preoperative planning and careful surgical technique especially flap advancement.

The Role of Occlusion in Implant Therapy: A Comprehensive Updated Review.

PURPOSE: Occlusal overload may cause implant biomechanical failures, marginal bone loss, or even complete loss of osseointegration. Thus, it is important for clinicians to understand the role of occlusion in implant long-term stability. This systematic review updates the understanding of occlusion on dental implants, the impact on the surrounding peri-implant tissues, and the effects of occlusal overload on implants. Additionally, recommendations of occlusal scheme for implant prostheses and designs were formulated. MATERIALS AND METHODS: Two reviewers completed a literature search using the PubMed database and a manual search of relevant journals. Relevant articles from January 1950 to September 20, 2015 published in the English language were considered. RESULTS: Recommendations for implant occlusion are lacking in the literature. Despite this, implant occlusion should be carefully addressed. CONCLUSION: Recommendations for occlusal schemes for single implants or fixed partial denture supported by implants include a mutually protected occlusion with anterior guidance and evenly distributed contacts with wide freedom in centric relation. Suggestions to reduce occlusal overload include reducing cantilevers, increasing the number of implants, increasing contact points, monitoring for parafunctional habits, narrowing the occlusal table, decreasing cuspal inclines, and using progressive loading in patients with poor bone quality. Protecting the implant and surrounding peri-implant bone requires an understanding of how occlusion plays a role in influencing long-term implant stability.

Dental Students' Perceived Value of Peer-Mentoring Clinical Leadership Experiences.

This pilot study compared second- and fourth-year dental students' perceived values of newly implemented clinical leadership experiences (CLEs) at one U.S. dental school during the 2012-13 academic year. In the CLEs, fourth-year (D4) students mentored second-year (D2) dental students during faculty-supervised patient treatment. The two cohorts' perceived value of the experiences was measured with questionnaires consisting of five-point Likert scale questions and open text responses. Out of a total of 114 D2 and 109 D4 students, 46 D2 students and 35 D4 students participated (response rates of 40.4% and 32.1%, respectively). While responses from both cohorts showed they highly valued the CLEs, the D2s perceived greater value: 4.07 (0.53) v. 3.51 (0.95), p<0.003. Both cohorts reported feeling that D4s were prepared to mentor D2s, that the CLEs had educational benefits, and that the CLEs increased their comfort with peer communication. Theme analysis of open text questions revealed that the respondents perceived the D4s were more accessible than faculty and provided guidance and individual attention; the CLEs increased student comfort; the CLEs reinforced D4 skills, knowledge, and confidence; and the CLEs provided management, leadership, and collaborative work experience. Theme analysis also highlighted student concerns about a lack of program structure. Overall, the majority of both groups valued CLEs in their dental education. Particular advantages they perceived were increased comfort, guidance, and attention. Further program development should address student concerns. These results suggest that similar programs should be considered and/or expanded in other dental schools' curricula.

Systemic Chemotherapeutic Agents as Adjunctive Periodontal Therapy: A Narrative Review and Suggested Clinical Recommendations.

Periodontitis is an inflammatory condition of the periodontium that leads to destruction of the supporting structures of the tooth, including loss of attachment and alveolar bone. A clinician's first line of treatment for periodontitis is traditionally mechanical periodontal therapy, including oral hygiene instructions together with scaling and root planing. How- ever, it has been shown that mechanical therapy may not always be effective in halting disease. Adjunctive chemotherapeutics, such as systemic antibiotics or host-modulating agents, may improve the treatment outcome of periodontitis. Using relevant terms such as "adjunctive antibiotics" and "systemic chemotherapeutics" in a manual search of the PubMed database, the authors have prepared a narrative review of the chemotherapeutics currently used in the field. Results of the search and review show that adjunctive antibiotics may be useful in cases of aggressive periodontitis, refractory periodontitis, and in some patients who are immunocompromised, such as heavy smokers or poorly controlled diabetics. Host-modulating agents are generally recommended only as the last resort and are limited to the use of submicrobial dose doxycycline. Microbial testing may be indicated, particularly in aggressive periodontitis cases or refractory cases. Using these results, a decision tree is provided for clinicians to determine when adjunctive chemotherapeutics may be indicated.