Radiographic evaluation of modern oral implants with emphasis on crestal bone level and relevance to peri-implant health

Convolutional neural network-based measurement of crown-implant ratio for implant-supported prostheses

STATEMENT OF PROBLEM

Research has revealed that the crown-implant ratio (CIR) is a critical variable influencing the long-term stability of implant-supported prostheses in the oral cavity. Nevertheless, inefficient manual measurement and varied measurement methods have caused significant inconvenience in both clinical and scientific work.

PURPOSE

This study aimed to develop an automated system for detecting the CIR of implant-supported prostheses from radiographs, with the objective of enhancing the efficiency of radiograph interpretation for dentists.

MATERIAL AND METHODS

The method for measuring the CIR of implant-supported prostheses was based on convolutional neural networks (CNNs) and was designed to recognize implant-supported prostheses and identify key points around it. The experiment used the You Only Look Once version 4 (Yolov4) to locate the implant-supported prosthesis using a rectangular frame. Subsequently, two CNNs were used to identify key points. The first CNN determined the general position of the feature points, while the second CNN finetuned the output of the first network to precisely locate the key points. The network underwent testing on a self-built dataset, and the anatomic CIR and clinical CIR were obtained simultaneously through the vertical distance method. Key point accuracy was validated through Normalized Error (NE) values, and a set of data was selected to compare machine and manual measurement results. For statistical analysis, the paired t test was applied (α=.05).

RESULTS

A dataset comprising 1106 images was constructed. The integration of multiple networks demonstrated satisfactory recognition of implant-supported prostheses and their surrounding key points. The average NE value for key points indicated a high level of accuracy. Statistical studies confirmed no significant difference in the crown-implant ratio between machine and manual measurement results (P>.05).

CONCLUSIONS

Machine learning proved effective in identifying implant-supported prostheses and detecting their crown-implant ratios. If applied as a clinical tool for analyzing radiographs, this research can assist dentists in efficiently and accurately obtaining crown-implant ratio results.

Influence of the Tube Angle on the Measurement Accuracy of Peri-Implant Bone Defects in Rectangular Intraoral X-ray Imaging

BACKGROUND

Intraoral radiography in the right-angle technique is the standard procedure to examine the peri-implant bone level in implant follow-up and implant-related studies. For the implementation of the right-angle or parallel technique, mostly ready-made image receptor holders are used. The aim of this experimental study is to analyze changes in the measurement of standardized peri-implant defects caused by a deviation in the position of the image receptor.

METHODS

Eleven Xive® implants (Dentsply Sirona, Bensheim, Germany) were placed in bovine bone, and peri-implant defects of varying depths were created. The preparations were fixed in a specially made test stand, and intraoral radiographs were taken using the right-angle technique with standard film holders at various horizontal and vertical projection angles. Defect measurement was carried out with the imaging software Sidexis 4 V 4.3 (Dentsply Sirona, Bensheim, Germany).

RESULTS

With increasing angular deviation, larger deviations between the measured and the real extent of the defect occurred. Vertical tilting caused significant distortion, while horizontal rotation showed less effect.

CONCLUSION

Intraoral radiography only provides a valid representation of the peri-implant bone level for follow-up or as a tool in implant-related studies if a reproducible projection direction is assured.

Knowledge and attitude of dental students regarding etiology, diagnosis, and treatment of peri-implantitis

OBJECTIVE

The objective of this study was to assess the level of knowledge and attitude of dental students about the etiology, diagnosis, and management of peri-implantitis.

METHODS

An online cross-sectional study that targeted senior undergraduate dental students at the College of Dentistry was conducted. A closed-ended survey consisting of 28 questions was designed. Three sections were created: 1) participants' characteristics; 2) Knowledge of peri-implantitis etiology, risk factors, diagnosis, and complications; 3) The use of antibiotics in peri-implantitis, diagnosis, and treatment methods. SPSS version 22 (IBM Corp.) was used for data analysis. Counts and percentages were calculated for correct answers in each section.

RESULTS

A total of 267 dental students responded to the questionnaire. The majority of the participants (81.6%) were knowledgeable about peri-implantitis being an inflammatory reaction, and a lesser percentage (77.9%) knew that bacterial plaque is an etiologic factor for peri-implant diseases. 82.0% of the participants identified smoking as a risk factor, followed by periodontitis (80.5%). Regarding implant complications, 57.3% of the participants considered implant mobility as a definitive indication for implant removal. More than half of the participants reported using crater-like bone defects surrounding implants to diagnose peri-implantitis. The most commonly used antibiotic was amoxicillin (34.1%), followed by amoxicillin combined with metronidazole (26.9%).

CONCLUSION

Most participants had a basic understanding of the etiology and risk factors of peri-implantitis. On the other hand, more courses addressing peri-implantitis diagnosis are needed.

Applying artificial intelligence to detect and analyse oral and maxillofacial bone loss-A scoping review

Radiographic evaluation of bone changes is one of the main tools in the diagnosis of many oral and maxillofacial diseases. However, this approach to assessment has limitations in accuracy, inconsistency and comparatively low diagnostic efficiency. Recently, artificial intelligence (AI)-based algorithms like deep learning networks have been introduced as a solution to overcome these challenges. Based on recent studies, AI can improve the detection accuracy of an expert clinician for periapical pathology, periodontal diseases and their prognostication, as well as peri-implant bone loss. Also, AI has been successfully used to detect and diagnose oral and maxillofacial lesions with a high predictive value. This study aims to review the current evidence on artificial intelligence applications in the detection and analysis of bone loss in the oral and maxillofacial regions.

Advancements in oral and maxillofacial surgery medical images segmentation techniques: An overview

OBJECTIVES

This article reviews recent advances in computer-aided segmentation methods for oral and maxillofacial surgery and describes the advantages and limitations of these methods. The objective is to provide an invaluable resource for precise therapy and surgical planning in oral and maxillofacial surgery. Study selection, data and sources: This review includes full-text articles and conference proceedings reporting the application of segmentation methods in the field of oral and maxillofacial surgery. The research focuses on three aspects: tooth detection segmentation, mandibular canal segmentation and alveolar bone segmentation. The most commonly used imaging technique is CBCT, followed by conventional CT and Orthopantomography. A systematic electronic database search was performed up to July 2023 (Medline via PubMed, IEEE Xplore, ArXiv, Google Scholar were searched).

RESULTS

These segmentation methods can be mainly divided into two categories: traditional image processing and machine learning (including deep learning). Performance testing on a dataset of images labeled by medical professionals shows that it performs similarly to dentists' annotations, confirming its effectiveness. However, no studies have evaluated its practical application value.

CONCLUSION

Segmentation methods (particularly deep learning methods) have demonstrated unprecedented performance, while inherent challenges remain, including the scarcity and inconsistency of datasets, visible artifacts in images, unbalanced data distribution, and the "black box" nature.

CLINICAL SIGNIFICANCE

Accurate image segmentation is critical for precise treatment and surgical planning in oral and maxillofacial surgery. This review aims to facilitate more accurate and effective surgical treatment planning among dental researchers.

A Systematic Review and Meta-Analysis of the Clinical Outcomes for Adjunctive Physical, Chemical, and Biological Treatment of Dental Implants With Peri-Implantitis

The present systematic review evaluated the efficacy of adjunctive therapies in the treatment of peri-implantitis. Studies comparing the outcome of conventional surgical- or nonsurgical mechanical debridement with the addition of an adjunctive therapeutic modality were identified through an electronic and hand search of available literature. Following data extraction, meta-analyses were performed on the primary outcome measures. The effects of the adjunctive therapies on bleeding on probing (13 studies), probing pocket depth (9 studies), and radiographic bone level changes (7 studies) were analyzed to evaluate potential clinical benefit. Heterogeneity was expressed as the I2 index. Fixed and random effect models were demonstrated. The potential benefit of adjunctive therapies over control procedures was evaluated in 18 studies, representing a total of 773 implants. Quality assessment of the studies found only 3 studies to be at a low risk of bias. Meta-analysis among the different additional modalities revealed chemical therapy demonstrating significant effects in probing pocket depth reduction (0.58 mm; 0.44-0.72) and radiographic bone level gain (0.54 mm; 0.16-0.92). No significant improvements in bleeding on probing reduction were found using any adjunctive therapy. Available evidence on the benefits of adjunctive therapy to nonsurgical or surgical mechanical debridement in the treatment of peri-implantitis is limited by low numbers of standardized, controlled studies for individual therapies, heterogeneity between studies, and a variety of outcome measures. The lack of effect of any adjunctive therapy in reducing bleeding on probing questions the overall effectiveness over conventional treatment. The long-term clinical benefit potential of these therapies is not demonstrated.

Marginal Bone Level Evaluation of Fixed Partial Dental Prostheses Using Preformed Stock versus CAD/CAM Customized Abutments

Background: The maintenance of marginal bone levels around dental implants is an important criterion for evaluating the success of implants. Although computer-aided design/computer-aided manufacturing (CAD/CAM) customized abutments (CAs) provide more flexible solutions, compared with the original preformed stock abutments (PAs), there are dimensional tolerances and underlying drawbacks in the production of CAD/CAM CAs, which may change the tightness and seamless connection between fixtures and abutments set by the manufacturer and then affect the long-term stability of the abutments. This study aimed to examine the change in both mesial and distal bone levels using digital periapical radiographs to evaluate the difference between CAD/CAM CAs and original PAs.Material and methods: Radiographs were taken before delivery; after functional loading for 1 month; and after 3, 6, and 12 months; and the vertical marginal bone levels (vMBLs) of both the mesial and distal surrounding implant bones were measured. All data are presented as means ± standard errors and were analyzed using Student’s t-test. A p-value < 0.05 was judged to represent a significant difference. Results: A total of 57 implants in 50 patients were divided into 22 CAD/CAM CAs and 35 original stock abutments. The PAs appeared to have a more stable bone level. By contrast, the amount of bone level change in the CAs was higher than that in the PAs. The change in the vMBL of the CAs was significantly more than that of the PAs after functional loading for 1 month (p = 0.006), 3 months (p = 0.013), 6 months (p = 0.014), and 12 months (p = 0.002). In contrast, the distal marginal bone level was lower than the mesial marginal bone level in any period. Nevertheless, the bone levels of the CAs and PAs in any period were comparable with no significant difference. Conclusions: Significant differences were found between the mesial and distal bone levels in the PAs. The CAD/CAM CAs showed a significantly greater bone level change than the original stock abutments after functional loading.

Clinical and Radiographic Evaluation of a Novel Triangular Implant Neck Design: A Case Series

The objective of this study was to evaluate the clinical and radiographic behavior of a novel triangular neck implant configuration in partially edentulous patients. Sixteen patients with a mean age of 58.3 years, were rehabilitated with 25 implants inserted in the healed sites of the maxilla and mandible; implant diameter was Ø3.3 and 3.9 mm. Clinical and radiographic measurements were first performed at prosthesis delivery that served as baseline; they were further evaluated after a mean period of 15.6 months. The interproximal peri-implant bone levels were the primary outcome; the mesial and distal data were recorded and a mean value was calculated. Secondary outcomes included peri-implant probing depth (PPD) and bleeding on probing (BoP). The paired t-test was used to compare the radiographic and clinical outcomes between baseline and follow-up. The mean bone levels at the mesial and distal aspects at baseline were 0.45 (0.47) and 0.57 (0.69), respectively; at follow-up they were 0.59 (0.42) and 0.78 (0.59), respectively. The differences were not statistically significant. Similarly, no significant differences were found for the clinical parameters. Within the limitations of the present study, it could be concluded that this new triangular neck bone level implant macro-design was used successfully to treat partially edentulous patients. Larger controlled clinical studies are warranted to confirm the present radiographic and clinical findings.

Radiographic evaluation of a novel bone adhesive for maintenance of crestal bone around implants in canine oversized osteotomies

BACKGROUND

A novel bone adhesive (tetracalcium phosphate and O-phospho-L-serine) has been developed as an osteoconductive, biodegradable bone-adherent material. The purpose of this study was to evaluate the maintenance of crestal bone/material level by standardized radiographs.

METHODS

This was a randomized, controlled, three arm, prospective study. Twenty-six mixed breed hound dogs were included in this study. Three implants were placed on either side of the mandible with either bone adhesive (BA), bovine bone mineral (BBM), or no biomaterial (negative control [NC]). Standardized periapical radiographs were taken immediately after implant placement and at every month up to 1 year. The vertical distance between the implant platform to the first radiopaque material on both the mesial and distal surfaces were measured and crestal bone/material level changes were analyzed.

RESULTS

The crestal bone/material level adjacent to BA was stable and maintained throughout the study. There were statistically significant differences found between BA and NC in terms of maintenance of crestal bone levels at any given timepoint.

CONCLUSION

This study demonstrated that BA maintained crestal bone levels and had a similar ability to maintain that level over 1 year compared with BBM.

Early crestal bone loss around implants placed at previously failed sites compared with initially integrated implants: A retrospective cohort study

BACKGROUND

There is minimal information on early crestal bone loss (CBL) associated with implants placed at failed sites.

PURPOSE

This retrospective cohort study aimed to evaluate CBL of surviving and restored implants placed at previously failed sites (replaced implants [RIs]) compared to that of implants initially integrated and restored (pristine implants [PIs]), within the same subjects from implant placement to 17 months post-delivery of restoration.

METHODS

Subjects who had both PI(s) and RI(s) were recruited. The following data were retrieved: patient demographics, implant locations, types of implant failure, use of bone graft procedure(s), and intraoral radiographs at implant placement (T0), restoration delivery (T1), and the post-restoration follow-up (T2). A blinded evaluator measured crestal bone levels at T0, T1, and T2.

RESULTS

Forty-four implants (22 in the RI and 22 in the PI group) from the 22 subjects were reviewed. The 22 implants in the RI group were placed either at early failure (17) or late failure (5) sites. There was a 4.6 times higher likelihood of bone graft procedures performed in association with RIs compared to PIs when using a generalized linear mixed model. Differences in crestal bone levels were compared between the two groups at each time point. There were no significant differences in the mesial and mean crestal bone levels between the PI and RI groups. The RI group exhibited lower crestal bone levels on the distal side compared to the PI group at all time points. However, this difference was due to crestal bone level at T0 (p = 0.039) not due to implant replacement (p = 0.413) or bone graft procedure (p = 0.302) when using mixed regression modeling.

CONCLUSION

The effect of replacements of implants at failed sites on CBL was not significant. RIs, once integrated, exhibited the same pattern of CBL as pristine implants.

Management and prevention of soft tissue complications in implant dentistry

The management and prevention of soft tissue complications is of key importance in modern implant dentistry and influences biologic and esthetic outcomes. The assessment of the soft tissue conditions from a quantitative and qualitative perspective should, therefore, be part of the overall treatment plan. Such an assessment dictates a potential indication as well as an ideal time point for additional soft tissue management. A proper risk assessment and management of the soft tissues at the planned implant site are of key importance prior to any implant‐related surgery. Cases with peri‐implant soft tissue complications generally involve: (a) a lack of attached and keratinized mucosa; (b) insufficient volume; (c) development of mucosal dehiscences; or (d) a combination of (a), (b), and (c). In case of soft tissue deficiencies, these should be addressed as early as possible to increase the predictability of the surgical interventions. This article reviews the main causes for peri‐implant soft tissue complications and presents different therapeutic options for the management of various clinical scenarios.

Do postoperative antibiotics influence one-year peri-implant crestal bone remodelling and morbidity? A double-blinded randomized clinical trial

Objectives

The primary objective of this study was to assess whether giving postoperative antibiotics to healthy patients after straightforward platform‐switched implant placement would influence peri‐implant crestal bone levels and postoperative morbidity after 1 year.

Methods

Thirty‐eight healthy individuals were recruited in this pilot, randomized, double‐blinded, placebo‐controlled clinical trial. The intervention group (n = 18) received two grams of amoxicillin one hour before implant placement followed by a 7 days postoperative regimen (500 mg tid). The control group (n = 20) took the same preoperative dose of amoxicillin and an identical placebo postoperatively. Mesial and distal peri‐implant crestal bone levels were measured at baseline, four months and one year later with standardized periapical radiographs. Postoperative pain severity was assessed through self‐administered questionnaires for 7 days. Surgery‐associated morbidities were evaluated after one, three, 16 weeks and 1 year. Descriptive and bivariate analyses were used.

Results

Thirty‐seven participants completed the trial. At the one‐year follow‐up, the mean combined peri‐implant crestal bone changes for the intervention (n = 18) and control (n = 19) groups were ‐ 0.44 ± 0.41 mm and ‐ 0.27 ± 0.56 mm, respectively. The difference between the groups (intervention–control) for mean combined crestal bone level changes was not statistically significant. There were no significant differences in surgery‐associated morbidities between the intervention and control groups. The one‐year implant survival rate was 100% in both groups.

Conclusions

Study results suggest that a routine postoperative antibiotic regimen for healthy patients undergoing straightforward platform‐switched implant placement might not be necessary to prevent postoperative peri‐implant bone loss and complications.

Measuring peri-implant bone lesions using low-dose cone-beam computed tomography

PURPOSE

High-definition cone-beam computed tomography (HD-CBCT) offers superior image quality at the cost of higher radiation dose compared to low-dose CBCT (LD-CBCT). The aim of this study was to investigate whether peri-implant bone lesions can be accurately quantified using LD-CBCT, even when including the influence of surrounding tissues.

METHODS

Twelve titanium implants restored with all-ceramic crowns were placed in bovine bone, and peri-implant lesions were prepared. Radiographic imaging was performed using IR (intraoral radiography), HD-CBCT and LD-CBCT. To simulate the in-vivo situation, the samples were placed inside a dry human mandible, and a second LD-CBCT imaging was performed (LD-CBCT*). The datasets were presented to four observers in random order. Maximum lesion depth and width were measured in a standardized mesiodistal slice in IR, HD-CBCT, LD-CBCT, and LD-CBCT*. Mean lesion depth and width measurements for each sample in HD-CBCT served as reference.

RESULTS

Interrater agreement was slight for depth and excellent for width in HD-CBCT and both LD modes. For all observers, measurement deviations from HD-CBCT were below 0.3 mm in the LD protocols (LD-CBCT depth: 0.22 ± 0.17 mm, width: 0.22 ± 0.13 mm; LD-CBCT* depth: 0.24 ± 0.23 mm, width: 0.25 ± 0.21 mm) and at 0.4 mm in IR.

CONCLUSIONS

Absolute differences between LD-CBCT and HD-CBCT are small, although surrounding tissues decrease LD-CBCT image quality. Within the limitations of an in-vitro trial, LD-CBCT may become an adequate imaging modality for monitoring peri-implant lesions at a substantially decreased radiation dose.

Early peri-implant bone loss as a predictor for peri-implantitis: A 10-year prospective cohort study

PURPOSE

To evaluate the effect of early bone loss (EBL), on long-term bone stability and future peri-implantitis development.

MATERIALS AND METHODS

Patients referred for implant placement between 2005 and 2009 were consecutively treated and followed for 10 years. After 10 years, patients were invited for a scientific diagnostic visit to evaluate implant survival and bone loss. Bone level changes were compared with baseline. Non-parametric testing was performed in cross-tabs (Pearson Chi-square and Fishers's exact test). Kaplan-Meier-estimated survival curves were plotted for different thresholds for EBL at different timepoints. Generalized linear mixed models with binomial distribution and logit link for peri-implantitis were fitted. An adjusted logistic mixed model was made to evaluate peri-implantitis, in relation with smoking status, history of periodontitis, and EBL > 0.5 mm.

RESULTS

Four hundred and seven patients (mean age of 64.86 years [range 28-92, SD 10.11]), with 1482 implants, responded to the 10-year recall invitation. After an average follow-up time of 10.66 years (range 10-14, SD 0.87), implant survival was 94.74%. Mean crestal bone loss after 10 years was 0.81 mm (SD 1.58, range 0.00-17.00). One hundred and seventy five implants in 76 patients had peri-implantitis (11.8% on implant level, 18.7% on patient level). EBL of 0.5, 1, and 2 mm were significant predictors for peri-implantitis and implant loss after 10 years. Implants with EBL ≥0.5 mm during the first year of function showed a 5.43 times higher odds for future peri-implantitis development. Probability in developing peri-implantitis was 52.06% when smoking, Periodontal history and EBL of >0.5 mm was combined.

CONCLUSION

The present study suggests that EBL is a predictor for long-term peri-implant pathology, with a significant higher risk for peri-implantitis when early bone loss exceeds the thresholds of 0.5 and 1 mm, especially when additional risk factors such as smoking or susceptibility for periodontal disease prior to implant treatment are present. Clinical trial registration number B670201524796.

Management of extensive peri-implant defects with titanium meshes

PURPOSE

Peri-implantitis is a biofilm-induced pathological condition, and different approaches have been proposed to manage this condition. This study introduces a surgical technique in accordance with the concept of guided bone regeneration for implants with extensive peri-implant defects.

METHODS

This pilot study was conducted on 7 patients with 11 implants (4 females and 3 males; 32 to 61 years). In this technique, we used a titanium mesh, a combination of autogenous bone, allogenic graft material, and acellular dermal matrix to reconstruct the peri-implant defects. All implants were placed submerged, and the second-stage surgery was conducted after 8 months. Soft tissue augmentation and vestibuloplasty were performed in the second-stage surgery, if required.

RESULTS

The mean function time of implants was 60.5 ± 29.4 months. The mean baseline probing pocket depth was 5.7 ± 1.4 mm, and soft tissue recession was observed at two sites (18%). The mean recession and keratinized tissue width (KTW) values were 0.4 ± 0.8 mm and 3 ± 1.6 mm, respectively. The mean marginal bone loss and bone gain were 4.4 ± 1.2 mm and 2.9 ± 0.9 mm, respectively, which showed a significant improvement.

CONCLUSION

Our preliminary evaluations showed favorable results in terms of radiographic defect fill and soft tissue condition. It appears that this technique may lead to promising outcomes in cautiously selected patients seeking to retain their failing implants. However, long-term results following functional loading are required before recommending this technique for daily practice.

Interproximal open contacts between implant restorations and adjacent natural teeth as a risk-indicator for peri-implant disease-A cross-sectional study

OBJECTIVES

The primary aim of this study was to investigate the relationship between interproximal open contacts and peri-implant disease. The secondary aim was to assess patient-reported outcome measures in relation to contact status.

MATERIALS AND METHODS

A cross-sectional study was performed on 61 patients with 142 implants adjacent to at least one natural tooth. Patients underwent a clinical examination to assess contact status and width, plaque index (PI), gingival index (GI), periodontal probing depths (PPD), and bleeding on probing (BoP). Radiographic marginal bone level was measured in vertical bitewings taken within one year. A diagnosis was given to each implant. Last, subjects completed a brief questionnaire. Rao-scott chi-squared tests and generalized estimating equations (GEE) models were used to compare outcomes between groups.

RESULTS

Seventy-seven (54.2%) implants were found to have ≥1 interproximal open contact. Sixty-five (45.8%) implants had closed contacts only. Implants with interproximal open contacts were significantly associated with peri-implant mucositis and peri-implantitis (p = .003) and increased prevalence of peri-implant disease (adjusted PR = 1.57; 95% CI: 1.09-2.27, p = .015). Open contact status was also associated with higher PPD (p = .045), PI scores (p = .036), and GI scores (p = .021). Open contact prevalence was 75.4% on the patient-level and 54.2% on the implant-level, involving the mesial surface of the implant restorations 68.5% of the time (p < .001).

CONCLUSION

Interproximal open contacts between implant restorations and adjacent natural teeth are a risk indicator for peri-implant disease. Adequate contact between implant restorations and natural teeth may contribute to the health of peri-implant tissues.

Peri-Implant Bone Loss Measurement Using a Region-Based Convolutional Neural Network on Dental Periapical Radiographs

Determining the peri-implant marginal bone level on radiographs is challenging because the boundaries of the bones around implants are often unclear or the heights of the buccal and lingual bone levels are different. Therefore, a deep convolutional neural network (CNN) was evaluated for detecting the marginal bone level, top, and apex of implants on dental periapical radiographs. An automated assistant system was proposed for calculating the bone loss percentage and classifying the bone resorption severity. A modified region-based CNN (R-CNN) was trained using transfer learning based on Microsoft Common Objects in Context dataset. Overall, 708 periapical radiographic images were divided into training (n = 508), validation (n = 100), and test (n = 100) datasets. The training dataset was randomly enriched by data augmentation. For evaluation, average precision, average recall, and mean object keypoint similarity (OKS) were calculated, and the mean OKS values of the model and a dental clinician were compared. Using detected keypoints, radiographic bone loss was measured and classified. No statistically significant difference was found between the modified R-CNN model and dental clinician for detecting landmarks around dental implants. The modified R-CNN model can be utilized to measure the radiographic peri-implant bone loss ratio to assess the severity of peri-implantitis.

Diagnostic accuracy of CBCT versus intraoral imaging for assessment of peri-implant bone defects

Background

Early detection of marginal bone loss is vital for treatment planning and prognosis of teeth and implant. This study was conducted to assess diagnostic accuracy of CBCT compared to intra-oral (IO) radiography for detection, classification, and measurement of peri-implant bone defects in an animal model.

Methods

Fifty-four mandible blocks with implants were harvested from nine male health adult beagle dogs with acquisition of IO, CBCT and micro-CT images from all samples. Peri-implant bone defects from 16 samples were diagnosed using micro-CT and classified into 3 defect categories: dehiscence (n = 5), infrabony defect (n = 3) and crater-like defect (n = 8). Following training and calibration of the observers, they asked to detect location (mesial, distal, buccal, lingual) and shape of the defect (dehiscence, horizontal defect, vertical defect, carter-like defect) utilizing both IO and CBCT images. Both observers assessed defect depth and width on IO, CBCT and micro-CT images at each side of peri-implant bone defect via CT-analyzer software. Data were analyzed using SPSS software and a p value of < 0.05 was considered as statistically significant.

Results

Overall, there was a high diagnostic accuracy for detection of bone defects with CBCT images (sensitivity: 100%/100%), while IO images showed a reduction in accuracy (sensitivity: 69%/63%). Similarly, diagnostic accuracy for defect classification was significantly higher for CBCT, whereas IO images were unable to correctly identify vestibular dehiscence, with incorrect assessment of half of the infrabony defects. For accuracy of measuring defect depth and width, a higher correlation was observed between CBCT and gold standard micro-CT (r = 0.91, 95% CI 0.86–0.94), whereas a lower correlation was seen for IO images (r = 0.82, 95% CI 0.67–0.91).

Conclusions

The diagnostic accuracy and reliability of CBCT was found to be superior to IO imaging for the detection, classification, and measurement of peri-implant bone defects. The application of CBCT adds substantial information related to the peri-implant bone defect diagnosis and decision-making which cannot be achieved with conventional IO imaging.

Evaluation of Alveolar Bone Quality: Correlation Between Histomorphometric Analysis and Lekholm and Zarb Classification

OBJECTIVES

This study evaluated the bone quality of the maxilla and mandible by using the classification proposed by Lekholm and Zarb (L & Z) and histomorphometry.

METHODS

Sixty edentulous areas were evaluated. The classification by L & Z was obtained through the evaluation of periapical and panoramic radiographs associated with the surgeon's tactile perception during milling and implant installation. Before implant installation, bone biopsies of standardized sizes were performed for histological evaluation.

RESULTS

Type III bone quality was more frequent in the posterior (73.33%) and anterior (73.33%) maxilla, whereas type II bone quality was more frequent in the posterior (53.33%) and anterior (60.00%) mandible. Through histometry, statistical difference was observed for the amount of bone tissue of the posterior region of the maxilla in relation to the anterior and posterior regions of the mandible (P ≤ 0.043). However, there was no difference in osteocyte counts between alveolar regions (P = 0.2946). In the female gender, the age showed a low positive correlation with the L & Z classification (rho = 0.398; P = 0.006) and in the male gender, a moderate negative correlation was observed (rho = -0.650, P = 0.016).

CONCLUSIONS

Both methods detected differences in the bone quality of the alveolar regions of the maxilla/mandible and that the classification by L & Z is a reliable method, since it was consistent with histomorphometry, considered the "gold standard" method for the evaluation of bone quality and greater bone density was observed in older men.

Early Loading of Mandibular Molar Single Implants: 1 Year Results of a Randomized Controlled Clinical Trial

The purpose of this study was to compare the implant survival, peri-implant marginal bone level, and peri-implant soft tissue of three different types of implants. This was performed with an early loading protocol, using a complete digital workflow, for one year of follow-up. Twenty-four patients with a single missing tooth in the mandibular posterior region were randomly assigned to the control group (SLActive Bone level implant; Institut Straumann AG, Basel, Switzerland), experiment group 1 (CMI IS-III Active implant; Neobiotech Co., Seoul, Korea), and experiment group 2 (CMI IS-III HActive implant; Neobiotech Co., Seoul, Korea). For each patient, a single implant was installed using the surgical template, and all prostheses were fabricated using a computer-aided design/computer-aided manufacturing system on a 3-dimensional model. A provisional prosthesis was implanted at 4 weeks, and a definitive monolithic zirconia prosthesis was substituted 12 weeks following the implant placement. The implant stability quotient (ISQ) and peri-implant soft tissue parameters were measured, and periapical radiographs were taken at 1, 3, 4, 8, 12, 24, 36, and 48 weeks after implant placements. Seven implants in the control group, nine implants in the experiment 1 group, and eight implants in the experiment 2 group were analyzed. There were no significant differences among the three groups in terms of insertion torque, ISQ values between surgery and 8 weeks of follow-up, marginal bone loss at 48 weeks of follow-up, and peri-implant soft tissue parameters (P > 0.05). Statistically significant differences in ISQ values were observed between the control and experiment 1 groups, and the control and experiment 2 groups at the 12 to 48 weeks' follow-ups. Within the limits of this prospective study, an early loading protocol can be applied as a predictable treatment modality in posterior mandibular single missing restorations, achieving proper primary stability.

Radiographic bone level around particular laser-treated dental implants: 1 to 6 years multicenter retrospective study

Purpose

The aim of the present retrospective study was to evaluate clinical and radiological outcomes, in terms of implant survival rate, marginal bone loss, and peri-implantitis incidence, of a titanium implants with an innovative laser-treated surface.

Materials and methods

A total of 502 dental implants were inserted in four dental practices (Udine, Arezzo, Frascati, Roma) between 2008 and 2013. All inserted implants had laser-modified surface characterized by a series of 20-μm-diameter holes (7–10 μm deep) every 10 μm (Synthegra®, Geass srl, Italy). The minimum follow-up period was set at 1 year after the final restoration. Radiographs were taken after implant insertion (T0), at time of loading (T1), and during the follow-up period (last recall, T2). Marginal bone loss and peri-implant disease incidence were recorded.

Results

A total of 502 implants with a maximum follow-up period of 6 years were monitored. The mean differential between T0 and T2 was 0.05 ± 1.08 mm at the mesial aspect and 0.08 ± 1.11 mm at the distal with a mean follow-up period of 35.76 ± 18.05 months. After being in function for 1 to 6 years, implants reported varying behavior: 8.8% of sites did not show any radiographic changes and 38.5% of sites showed bone resorption. The bone appeared to have been growing coronally in 50.7% of the sites measured.

Conclusion

Implants showed a maintenance of marginal bone levels over time, and in many cases, it seems that laser-modified implant surface could promote a bone growth. The low peri-implant disease incidence recorded could be attributed to the laser titanium surface features that seem to prevent bacterial colonization. Future randomized and controlled studies are needed to confirm the results of the present multi-centrical retrospective analysis.

Radiographic Evaluation in the Diagnosis of Alveolar Bone Quality in Implant Rehabilitation

This study evaluated the optical bone density of the maxilla and mandible and correlate with the classification of bone quality of the Lekholm and Zarb (L & Z). Sixty edentulous areas were evaluated. Panoramic and periapical radiographs were performed with an aluminum scale to evaluate the optical bone density. L & Z classification was also applied. By using periapical radiographs, a statistically significant difference was observed in the optical bone density of the posterior maxilla (2.38 ± 1.06) and the posterior mandible (3.84 ± 0.68), when compared to the other regions (P ≤ 0.015). However, with panoramic radiographs, no differences were observed in the optical bone density (P = 0.6322). A negative correlation was observed between the L & Z classification and the optical bone density obtained by the periapical radiographs (rho = -0.463; P < 0.001), that is, the worse the bone quality, the lower the bone density. However, there was no significant correlation with the bone density obtained by panoramic radiographs (rho = -0.009; P = 0.948). As for gender, a correlation between aging and the presence of medullary bone was observed in females, assessed by the L & Z classification (rho = 0.398; P = 0.006). However, there was a correlation between aging and a denser and less medullary presence in males, both assessed by the L & Z classification (rho = -650; P = 0.016), as well as the optical density assessed by periapical (rho = 0.621; P = 0.023) and panoramic (rho = 0.588; P = 0.035) radiographs. These results suggest that gender and age interfere with the bone quality and periapical radiographs are an acceptable method for evaluating bone density. However, a panoramic radiograph was not found to be a reliable method.

Attitude in Radiographic Post-Operative Assessment of Dental Implants among Italian Dentists: A Cross-Sectional Survey

There is a lack of evidence in the attitude and prescribing practice of implantologists in dental implant post-operative assessment; therefore, the aims of this cross-sectional study were to investigate these habits and the knowledge about radiographic aspect of retrograde peri-implantitis (RPI) among Italian implantologists. A questionnaire was sent via email to dentists randomly selected from the register of implantology and oral surgery societies. It included three questions: the preferred X-ray after implant placement, the timing of post-operative assessment and the knowledge of the RPI radiographic representation. A final sample of 434 implantologists was included in the study. The majority of them (84.3%) perform a periapical X-ray as control radiograph and picked the correct radiographic representation of RPI (74.3%), without statistically significant differences (p > 0.05) for sex, age, years of working practice and number of implants placed per year. Just 47.7% of dentists perform a control radiograph at prostheses delivery, to establish a proper baseline. A statistically significant difference (p < 0.05) was detectable only for the number of implants placed per year, with dentists placing > 80 implants selecting the correct choice. To the best of authors’ knowledge, this is the first study to report data on attitude of implantologists in radiographic imaging after implant placement.

[Accuracy of paralleling technique in measuring the depth of approximal infrabony pocket]

OBJECTIVE

To assess the accuracy of paralleling technique in measuring the depth of approximal infrabony pocket after periodontal flap surgery by comparing the measured and actual depths.

METHODS

The study population included 26 patients with infrabony defects who had undergone periodontal flap surgery, bone graft surgery, and guided tissue regene-ration. The measured and actual depths of approximal infrabony pocket after periodontal flap surgery were compared. The 26 infrabony defects were categorized into the following groups according to tooth position: anterior teeth, premolar, and molar groups, and according to type of infrabony pocket: one-walled, two-walled, and three-walled infrabony pocket groups. Paired t-test was used to detect the difference between the two values.

RESULTS

Depth measurements of the approximal infrabony pocket depth of the anterior teeth and premolar were not significantly different (P>0.05), whereas those of the molar group were significantly different (P<0.05). In addition, depth measurements in one-walled and two-walled infrabony pocket groups showed no significant differences (P>0.05), whereas those in the three-walled infrabony pocket group were significantly different (P<0.05).

CONCLUSIONS

Paral-leling technique can accurately measure the depth of approximal infrabony pockets of anterior teeth and premolar teeth that are one- or two-walled. However, this method cannot accurately measure the approximal infrabony pockets of molar teeth and three-walled infrabony pockets as indicated by significant differences in their depth measurements.

Cholinergic signalling mechanisms and early implant healing phases in healthy versus generalized aggressive periodontitis patients: A prospective, case-control study

AIMS

Periodontal diseases negatively affect implant osseointegration. Perturbations in non-neuronal cholinergic signalling mechanisms are associated with periodontitis; however, their role in generalized aggressive periodontitis (GAgP) is unknown. The aim of this prospective case-control study was to determine the relationship between non-neuronal cholinergic signalling mechanisms, secreted Ly-6/uPAR-related protein-1 (SLURP-1), interleukin-17 (IL-17) family cytokines and healing of dental implants in health and GAgP.

MATERIAL AND METHODS

Thirteen GAgP patients and seven periodontally healthy individuals (PH) were recruited. Peri-implant crevicular fluid (PICF) was obtained at baseline and 1 month post-placement. Acetylcholine (ACh) levels and cholinesterase activity were determined biochemically. SLURP-1, IL-17A and IL-17E levels were determined by ELISA. Marginal bone loss (MBL) at 1 and 6 months post-placement was determined radiographically.

RESULTS

The concentration of ACh, cholinesterase activity and IL-17A levels was elevated in PICF of patients with GAgP compared to PH individuals at baseline and 1 month post-placement. The concentration of ACh and cholinesterase activity levels in PICF correlated with levels of IL-17A and MBL around implants 1 month post-placement in patients with GAgP.

CONCLUSIONS

Non-neuronal cholinergic mechanisms may play a role in the aetiopathogenesis of GAgP and may directly or indirectly, through modulation of IL-17A, influence early implant osseointegration and potential long-term implant survival.

The Effect of Tapered Abutments on Marginal Bone Level: A Retrospective Cohort Study

Background: Early peri-implant bone loss has been associated to long-term implant-prosthetic failure. Different technical, surgical, and prosthetic techniques have been introduced to enhance the clinical outcome of dental implants in terms of crestal bone preservation. The aim of the present cohort study was to observe the mean marginal bone level around two-part implants with gingivally tapered abutments one year after loading. Methods: Mean marginal bone levels and change were computed following radiological calibration and linear measurement on standardized radiographs. Results: Twenty patients who met the inclusion criterion of having at least one implant with the tapered prosthetic connection were included in the study. The cumulative implant success rate was 100%, the average bone loss was −0.18 ± 0.72 mm, with the final bone level sitting above the implant platform most of the time (+1.16 ± 0.91 mm). Conclusion: The results of this cohort study suggested that implants with tapered abutments perform successfully one year after loading and that they are associated with excellent marginal bone preservation, thus suggesting that implant-connection macro-geometry might have a crucial role in dictating peri-implant bone levels.

Randomized controlled clinical trial on calcium phosphate coated and conventional SLA surface implants: 1-year study on survival rate and marginal bone level

BACKGROUND

Calcium phosphate (CaP)-coated surface showed enhanced contact osteogenesis around dental implant and finally accelerate osseointegration in early healing phase.

PURPOSE

The aim of this randomized controlled trial was to compare the peri-implant marginal bone level around uncoated and CaP-coated sandblasted, large-grit, acid-etched (SLA) surface implants during the first year after placement.

MATERIALS AND METHODS

This study was performed upon 34 patients with randomized and double-blinded design. Clinical and radiographic examinations were performed immediately after implant placement, at re-entry after 3 months, and after 12 months to evaluate the initial stability and change in the marginal bone level. The distance from the implant shoulder to the top of the bone-to-implant contact was defined as the marginal bone level, and its alteration was measured at 1 year after implant installation.

RESULTS

None of the implants failed, and most of them showed a marginal bone loss of less than 1 mm. Small changes in the bone level were noted at all sites in the control and test groups, and there were no clinically significant differences in the changes in the marginal bone.

CONCLUSION

Both CaP-coated and uncoated SLA surface implants showed comparably successful marginal bone stability without any complications during the first year after placement.

Metal Nanoparticles Released from Dental Implant Surfaces: Potential Contribution to Chronic Inflammation and Peri-Implant Bone Loss

Peri-implantitis is an inflammatory disease affecting tissues surrounding dental implants. Although it represents a common complication of dental implant treatments, the underlying mechanisms have not yet been fully described. The aim of this study is to identify the role of titanium nanoparticles released form the implants on the chronic inflammation and bone lysis in the surrounding tissue. We analyzed the in vitro effect of titanium (Ti) particle exposure on mesenchymal stem cells (MSCs) and fibroblasts (FU), evaluating cell proliferation by MTT test and the generation of reactive oxygen species (ROS). Subsequently, in vivo analysis of peri-implant Ti particle distribution, histological, and molecular analyses were performed. Ti particles led to a time-dependent decrease in cell viability and increase in ROS production in both MSCs and FU. Tissue analyses revealed presence of oxidative stress, high extracellular and intracellular Ti levels and imbalanced bone turnover. High expression of ZFP467 and the presence of adipose-like tissue suggested dysregulation of the MSC population; alterations in vessel morphology were identified. The results suggest that Ti particles may induce the production of high ROS levels, recruiting abnormal quantity of neutrophils able to produce high level of metalloproteinase. This induces the degradation of collagen fibers. These events may influence MSC commitment, with an imbalance of bone regeneration.

Prevalence of Peri-Implantitis in Implants with Turned and Rough Surfaces: a Systematic Review

Objectives

Moderately-rough implant surface may improve implant therapy in terms of bone integration, but the increased surface roughness might affect the initiation and development of peri-implantitis. The aim of the present review was to compare the prevalence of peri-implantitis in implants with rough and turned (machined) implant surfaces.

Material and Methods

An electronic literature search was conducted of the MEDLINE and EMBASE databases for articles published between 1 January 1990 and 1 March 2018. Clinical human studies in the English language that had reported on prevalence of peri-implantitis in tuned and rough surface implants were searched. The initial search resulted in 690 articles.

Results

Eight articles with 2992 implants were included in the systematic review. The incidence of peri-implantitis for two implant surfaces varied between studies. A meta-analysis was not feasible due to the heterogeneity among studies. Implant with rough surfaces were more favourable for plaque accumulation during short-term follow-up. On a long-term, turned implants surfaces were associated with more plaque and higher peri-implant bone loss. Peri-implant clinical parameters and survival rate for two implant surfaces was similar.

Conclusions

Within the limitations of the present study, rough implant surface does not seem to increase the incidence of peri-implantitis in comparison to turned implants surface.

How do peri-implant biologic parameters correspond with implant survival and peri-implantitis? A critical review

Objectives

The aim of this critical review was to evaluate whether commonly used biologic diagnostic parameters correspond to implant survival and peri‐implantitis prevalence.

Materials and methods

Publications from 2011 to 2017 were selected by an electronic search using the Pubmed database of the US National Library of Medicine. Prospective and retrospective studies with a mean follow‐up time of at least 5 years and reporting prevalence of peri‐implantitis as well as mean bone loss and standard deviation were selected. The correlation between reported prevalence of peri‐implantitis and reported implant survival, mean follow‐up time, mean bone loss, mean probing depth, and mean bleeding on probing was calculated. Mean bone loss and standard deviation were used for estimation of proportion of implants with bone loss exceeding 1, 2, and 3 mm.

Results

Full‐text analysis was performed for 255 papers from 4,173 available ones, and 41 met all the inclusion criteria. The overall mean weighted survival rate was 96.9% (89.9%–100%) and the reported prevalence of peri‐implantitis ranged between 0% and 39.7%, based on 15 different case definitions. The overall weighted bone loss was 1.1 mm based on 8,182 implants and an average mean loading time ranging from 5 to 20 years. No correlation was found between mean bone loss and the reported prevalence of peri‐implantitis. The estimated prevalence of implants with bone loss above 2 mm was 23%. The overall weighted mean probing depth was 3.3 mm, and mean weighted bleeding was 52.2%. Only a weak correlation was found between survival and function time (r = −0.49). There was no relation between the probing depth or bleeding and the mean bone loss, mean follow‐up time, and reported prevalence of peri‐implantitis.

Conclusion

Biologic parameters mean probing depth and mean bleeding on probing do not correlate with mean bone loss and this irrespective of follow‐up. Case definition for peri‐implantitis varied significantly between studies indicating that an unambiguous definition based on a specified threshold for bone loss is not agreed upon in the literature.

Retrospective cohort study of 4,591 dental implants: Analysis of risk indicators for bone loss and prevalence of peri-implant mucositis and peri-implantitis

Background

Due to the risk of peri‐implantitis, following dental implant placement, this study aimed to evaluate risk indicators associated with marginal bone loss from a retrospective open cohort study of 4,591 dental implants, placed in private practice, with 5‐ to 10‐year follow‐up. Furthermore, the prevalence of mucositis and peri‐implantitis among the study cohort was evaluated, comparing strict versus relaxed criteria for bleeding on probing.

Methods

Periapical radiographs were used to evaluate changes in crestal bone level. Peri‐implant soft tissue was evaluated using an ordinal mucosal index in comparison with the conventional binary threshold for bleeding (i.e., present or not). Periodontal probing depth was not evaluated. Linear mixed models were used to evaluate bone level over time, and other risk indicators, at the patient and implant level.

Results

Risk indicators found to have a significant impact on bone level included: autoimmune disease, heavy smoking, bisphosphonate therapy, implant location, diameter and design, and the presence of a bone defect at site of implantation. The prevalence of mucositis at the implant level was 38.6% versus 14.2% at 6 to 7 years, when using strict versus relaxed criteria, respectively. The prevalence of peri‐implantitis after 6 to 7 years was 4.7% and 3.6% when using strict versus relaxed criteria, respectively.

Conclusions

The results of this study identify several risk factors associated with bone loss. Furthermore, the prevalence of mucositis and peri‐implantitis was shown to be lower at both the implant and the patient when using strict versus relaxed criteria based on the assessment of oral health surrounding dental implants.

[Criteria for success in dental implants]

With the comprehensive application and development of implant dentistry in recent years, multi-institutional data have supported a large number of clinical research findings. A consensus was gradually reached on the evaluation of the state and effect of implants and types of indicators that were selected after restoration. This study aims to examine the frequently used criteria to define treatment success in implant dentistry.

Marginal bone loss around cement and screw-retained fixed implant prosthesis

Background

Implant-supported fixed restorations are considered as the standard treatment for replacement of missing teeth. These can be either screw or cement retained. The success or failure of implant restorations depend upon amount of marginal bone loss (MBL). The present study is to determine the MBL around cement and screw-retained implant prosthesis and to determine various predictors of the MBL.

Material and Methods

A retrospective charts review was conducted at the dental clinics, Aga Khan University Hospital, Karachi from February 2017 to June 2017 in which 104 implants restorations were assessed using periapical radiographs. MBL was calculated at baseline and at 12 months and the difference was recorded on a proforma. SPSS version 21.0 was used for statistical analysis. Descriptive statistics was computed. Generalized estimation equation analysis (GEE) was applied to determine the predictors of MBL. Level of significance was kept at ≤ 0.05.

Results

There were 104 implant restorations belonging to 41 patients. Screw retained prosthesis showed significantly greater MBL than cement retained prosthesis (p-value =0 .018) (irrespective of crowns or fixed partial dentures). Other factors that turned out to be significant predictors of MBL were male gender (p-value= <0.01), age >65 yrs. (p-value=0.028) and sites where bone grafting was performed (p-value=0.003).

Conclusions

Male patients of age >65 yrs. with sites needing bone grafts who were provided with screw retained prosthesis (irrespective of crown or fixed partial dentures) had significantly greater marginal bone loss around implants. Key words:Dental implants, dental prosthesis, implant supported dental prosthesis, alveolar bone loss.

Retrospective radiographic observational study of 1692 Straumann tissue-level dental implants over 10 years. II. Marginal bone stability

BACKGROUND

Despite accumulating evidence for the longitudinal stability of the marginal bone level around an implant, there is limited evidence of predisposing risk factors for marginal bone loss based on some implants in a relatively large patient population.

PURPOSE

The aim of this study was to retrospectively determine the marginal bone loss around Straumann tissue-level dental implants during follow-up periods among which the maximum lasts up to 10 years, as well as the predisposing risk factors for peri-implant marginal bone loss.

MATERIALS AND METHODS

This study analyzed 1692 Straumann tissue-level dental implants in 881 patients, and relevant data were collected. The peri-implant marginal bone level was measured on periodic radiographs, and the changes in bone level were analyzed cumulatively from surgery until up to 10 years later. The log-rank test was used to select candidate critical risk factors for marginal bone loss, and multivariate analysis using Cox regression with the shared frailty model was performed.

RESULTS

The overall peri-implant bone loss was 0.07 ± 0.21mm, 0.09 ± 0.26mm, 0.14 ± 0.41mm, and 0.17 ± 0.45mm at 3, 5, 7, and 9 years, respectively. Only 14 implants showed pathologic marginal bone loss exceeding 2mm during the follow-up period. While 2 implants were removed with continuous progressive marginal bone loss, 5 of the 14 implants showed early bone loss exceeding 1mm within the first year but then subsequently tended to show a stable marginal bone level. In the other seven implants, bone loss started after the first year and progressed continuously. Multivariate analysis revealed that diameter of the implant affected the peri-implant marginal bone loss.

CONCLUSIONS

Straumann tissue-level dental implants showed only slight peri-implant marginal bone loss, with a very low incidence of pathologic marginal bone loss exceeding 2mm.

Association of Smoking Habits and Height of Residual Bone on Implant Survival and Success Rate in Lateral Sinus Lift: A Retrospective Study

The primary aim was to evaluate the association of patient-related factors, biomaterials, and implant characteristics on complications' rate of sinus graft surgery and on implant survival rate in grafted sinus. Secondary aims were to measure bone remodeling around implants and patient satisfaction. A retrospective cohort study was designed. Patients who had computerized tomography (CT) before sinus surgery (T0), orthopantomography after implant surgery (T1) and at follow-up (T2), were included. Specific forms were used to collect clinical data. Radiographic measures were: height of residual bone before sinus surgery measured on CT (T0) and apical and marginal bone levels around implants measured on orthopantomography at T1 and T2. Forty-three lateral sinus lifts were performed. Three grafts failed before implant insertion. Out of 83 implants inserted in 29 patients, a total of 19 failed. Mean follow-up (T2) was 6 ± 1.8 years [4; 11.2 years]. The multilevel models analysis showed no association between complications rate and patient-related factors, biomaterials, and implant characteristics. Smoking (odds ratio [OR]: 8.3; 95% CI 1.46-48.05, P = .0173) and height of residual bone (OR: 0.32 for each mm; 95% CI 0.15-0.68, P = .0034) were associated with implant failure. Bone remodeling between T1 and T2 was -0.8 ± 0.2 mm for apical bone and -0.6 ± 0.3 mm for marginal bone. General therapy satisfaction measured in a visual analogue scale was 8.4 ±1.4. In conclusion, lower height of residual bone before sinus surgery and smoking habits had a negative prognostic effect on survival rate of dental implants placed in grafted sinuses.

Are intraoral radiographs reliable in determining peri-implant marginal bone level changes? The correlation between open surgical measurements and peri-apical radiographs

This study was performed to evaluate the reliability of peri-apical radiographs in determining peri-implant marginal bone level changes. The STROBE guidelines were followed. Marginal bone levels were measured at the time of implant insertion using a straight periodontal probe and using peri-apical radiographs. These intraoperative and radiographic measurements were repeated at the time of second surgery. All radiographs were analysed by two examiners blinded to the intraoperative measurements. To standardize the radiographic images, the long-cone parallel technique and a film-holding system were used. Intra-observer agreement and inter-observer variability were assessed using the intra-class correlation coefficient (ICC). Descriptive statistics, the t-test, and the Pearson correlation coefficient were also used. A total of 268 implants were inserted in 142 patients. Inter-observer agreement was 0.950; intra-observer variability was 0.980 and 0.973. The mean difference between the radiographic and intraoperative measurements was 0.50±1.55mm (range 0-8mm); the difference was statistically significant (P=0.000). A significant linear correlation was found between the marginal bone level changes evaluated intraoperatively and radiographically (P<0.005). Radiographic analysis significantly overestimated the level of peri-implant marginal bone compared to intraoperative measurements, but peri-apical radiographs are reliable in determining the bone level changes at different follow-ups.

Ten-year follow-up of dental implants used for immediate loading in the edentulous mandible: A prospective clinical study

PURPOSE

The purpose of this study is to evaluate the 10-year outcome of 25 patients with immediate loading in the edentulous mandible.

MATERIAL AND METHODS

Twenty-five patients were consecutively treated with 5 immediately loaded fluoride-modified implants in the edentulous mandible. Implant survival and bone loss were evaluated by an external researcher comparing digital periapical radiographs taken during recall visits with baseline (at implant insertion). Statistical descriptive analysis and nonparametric tests were performed using SPSS v23, multilevel analysis was performed by means of R version 3.1.0. to identify risk factors for bone loss.

RESULTS

Twenty-one patients (8 males, 13 females, mean age 68.4, range 49-84) responded to the 10-year recall invitation. No implants were lost during follow-up, resulting in a 100% survival rate. After 10 years, bleeding on probing and plaque were present at 49.5% and 67.6% of the sites, respectively. The mean pocket probing depth was 3.77 mm (SD 0.73, range 3.0-6.83). Bone loss on implant level after 3, 12, 24, and 120 months was 0.16 mm (SD 0.33, range 0-1.75), 0.14 mm (SD 0.24, range 0-1.05), 0.17 mm (SD 0.27, range 0-1.5), and 0.49 mm (SD 1.08, range 0-7.8). Five implants were identified with or at risk for progressive bone loss. Forty-seven percent of the implants did not show any bone loss after 10 years in function and 87% lost less than 1 mm. Multilevel statistical analysis identified 2-year bone loss as a predictor for bone loss after 10 years of function.

CONCLUSION

Immediate loading of 5 fluoride-modified dental implants with a fixed prosthetic rehabilitation is a predictable and reliable treatment in the edentulous mandible, based on a 100% implant survival and limited peri-implant bone loss. Implants used for immediate loading in the edentulous mandible who are showing early bone loss may be at higher risk to develop peri-implantitis.

Diagnostic performance of cone beam computed tomography in assessing peri-implant bone loss: A systematic review

OBJECTIVES

To evaluate the diagnostic performance of cone beam computed tomography (CBCT) in the assessment of peri-implant bone loss and analyze its influencing factors.

MATERIALS AND METHODS

Clinical and preclinical studies reporting diagnostic outcomes of CBCT imaging of peri-implant bone loss compared to direct reference measurements were sought by searching five electronic databases, PubMed, MEDLINE, EMBASE, Web of Science, and CINAHL Plus, and OpenGrey. QUADAS-2 criteria were adapted for quality analysis of the included studies. A qualitative synthesis was performed. Two meta-analysis models (random-effects and mixed-effects) summarized the area under receiver operating characteristic (AUC) curve observations reported in the selected studies. The mixed-effects meta-analysis model evaluated three possible influencing factors, "defect type," "defect size," and "study effect."

RESULTS

The initial search yielded 3,716 titles, from which 18 studies (13 in vitro and 5 animal) were included. Diagnostic accuracy of CBCT was fair to excellent in detecting in vitro circumferential-intrabony and fenestration defects, but moderate to low for peri-implant dehiscences, and tended to be higher for larger defect sizes. Both, over- and underestimation of linear measurements were reported for the animal models. The meta-analyses included 37 AUC observations from eight studies. The random-effects model showed significant heterogeneity. The mixed-effects model exhibited also significant but lower heterogeneity, and "defect type" and "study effect" significantly influenced the variability of AUC observations.

CONCLUSION

In vitro, CBCT performs well in detecting peri-implant circumferential-intrabony or fenestration defects but less in depicting dehiscences. Influencing factors due to other site-related and technical parameters on the diagnostic outcome need to be addressed further in the future studies.

Quantitative measurement of peri-implant bone defects using optical coherence tomography

Purpose

The purpose of this study was to visualize and identify peri-implant bone defects in optical coherence tomography (OCT) images and to obtain quantitative measurements of the defect depth.

Methods

Dehiscence defects were intentionally formed in porcine mandibles and implants were simultaneously placed without flap elevation. Only the threads of the fixture could be seen at the bone defect site in the OCT images, so the depth of the peri-implant bone defect could be measured through the length of the visible threads. To analyze the reliability of the OCT measurements, the flaps were elevated and the depth of the dehiscence defects was measured with a digital caliper.

Results

The average defect depth measured by a digital caliper was 4.88±1.28 mm, and the corresponding OCT measurement was 5.11±1.33 mm. Very thin bone areas that were sufficiently transparent in the coronal portion were penetrated by the optical beam in OCT imaging and regarded as bone loss. The intraclass correlation coefficient between the 2 methods was high, with a 95% confidence interval (CI) close to 1. In the Bland-Altman analysis, most measured values were within the threshold of the 95% CI, suggesting close agreement of the OCT measurements with the caliper measurements.

Conclusions

OCT images can be used to visualize the peri-implant bone level and to identify bone defects. The potential of quantitative non-invasive measurements of the amount of bone loss was also confirmed.

Initial and long-term crestal bone responses to modern dental implants

Successful osseointegration is the result of a controlled foreign body reaction to dental implants. Osseointegrated implants have demonstrated excellent long-term survivability, although they may be subject to limited marginal bone loss. Marginal bone loss during the first few years after implant placement seldom represents disease, but is instead the result of an adaptive bone response to surgical trauma and implant loading. It is not uncommon for implants with early marginal bone loss to enter a long-lasting state of bone stability. Extensive bone resorption after the first year is generally due to an exacerbation of adverse body reactions caused by non-optimal implant components, adverse surgery or prosthodontics and/or compromised patient factors. Disease in the form of peri-implantitis is a late complication that affects some implants with suppuration and rapid loss of crestal bone, and is probably caused by bacterial pathogens and immunological reactions. Unfortunately, the literature is not consistent with respect to the type or magnitude of clinical implant problems, including how they are defined and diagnosed. If the peri-implantitis diagnosis is confined to cases with infection, suppuration and significant bone loss, the frequency of the disease is relatively low, which is in sharp contrast to the frequencies reported with unrealistic definitions of peri-implantitis. We suggest that when modern implants are placed by properly trained individuals, only 1-2% of implants show true peri-implantitis during follow-up periods of 10 years or more. Peri-implantitis must be separated from the initial and self-limiting marginal bone loss.

Parameters Associated with Marginal Bone Loss around Implant after Prosthetic Loading

This study evaluated retrospectively the association among occlusal, periodontal and implant-prosthetic parameters and marginal bone loss (MBL) around implants and survival rate at 5.7 ±3.2 years of follow-up after prosthetic loading. Eighty-two patients received 164 external hexagon implants. After the standard healing period (3 to 6 months), the implants were restored with single-tooth or up to three splinted crowns. All patients were followed according to a strict maintenance program with regular recalls and clinically evaluated by a calibrated examiner. The MBL measurements taken from standardized radiographs made at permanent crown placement (baseline) and after the last evaluation were calculated considering occlusal, periodontal and implant-prosthetic parameters. Veneer fractures and abutment loosening were not considered failure. Two implants failed during the follow-up period, resulting in a survival rate of 98.8%. Cox regression analyses showed MBL associated with non-working side contacts (p=0.047), inadequate anterior guidance (p=0.001), lateral group guidance involving teeth and implants (p=0.015), periimplant plaque index (p=0.035), prosthetic design (p=0.030) and retention (p=0.006). Inadequate occlusal pattern guide, presence of visible plaque, and cemented and splinted implant-supported restoration were associated with greater MBL around the implant.