Risk factors observed in 2-dimensional radiographs for permanent injury of the inferior alveolar nerve after removal of mandibular third molars: a case-control study.

OBJECTIVE: To assess whether differences exist in signs observed in 2D radiographs of mandibular third molars between a case group of patients with and a control group without permanent sensory disturbance of the inferior alveolar nerve (IAN) after removal. STUDY DESIGN: Three observers blinded to patient status assessed radiographs from the case group (n=162) and the control group (n=172). Two new signs, craniocaudal relation of the roots and the mandibular canal and position of the canal over the roots; and 4 "classic" signs, interruption of the white borders of the canal, darkening of the roots, narrowing of the canal lumen, and diversion of the canal over the roots were registered. Chi-square tests assessed differences in distribution of radiographic signs between the groups. Odds ratios expressed the association between radiographic signs and permanent sensory disturbance. Inter- and intraobserver reliability values were calculated. RESULTS: We found significantly more teeth with roots positioned inferiorly to the canal borders (P<0.001; OR 4.1-5.3) and with the canal superimposed over the upper or middle third of the roots (P<0.001; OR 2.6-3.9) in the case group than in the control group. Inter- and intraobserver reproducibility was excellent for roots inferior to the canal borders and fair to good for canal superimposition. CONCLUSIONS: Two radiographic signs are valid predictors of permanent sensory disturbance of the IAN in 2D radiographs.

Reliability of radiographic findings in large FOV CBCTs of mandibular third molars as basis for pre-operative patient information.

OBJECTIVE: The aim of this study was to assess the relation between radiographic findings in large field of view (FOV) cone beam computed tomography (CBCT) exams and clinical findings of mandibular third molars in relation to the pre-operative patient information. MATERIAL AND METHODS: Two hundred and nine mandibular third molars in 134 orthognathic patients examined with CBCT were removed. Three observers assessed tooth- and mandibular canal-related variables in CBCT images, and the findings were correlated to clinical findings during surgery for all observers: tooth angulation, number and morphology of roots and close relationship between the tooth and the mandibular canal. Moreover, positive (PPV) and negative (NPV) predictive values and positive (LR+) and negative (LR-) likelihood ratios were calculated for the canal-related variables. Inter- and intra-observer reproducibility was expressed as percentage accordance and kappa-statistics. RESULTS: Generally, there was high correlation between radiographic and clinical tooth-related variables. The opposite was true for the canal-related variables, since the PPV and LR + were low. The highest PPV and LR + were found when the mandibular canal was positioned between the roots of the third molar. CONCLUSIONS: Tooth-related findings in CBCT are reliable, whereas mandibular canal-related findings should not affect the information provided to the patient pre-operatively.

Magnetic Resonance Imaging for the Planning, Execution, and Follow-up of Implant-Based Oral Rehabilitation: Systematic Review.

PURPOSE: To undertake a systematic literature review of magnetic resonance imaging (MRI) employed in the three phases of implant-based oral rehabilitation: planning, execution, and follow-up. MATERIALS AND METHODS: MEDLINE (PubMed) and EMBASE bibliographic databases were searched up to January 2020 for studies assessing the use of MRI alone or in connection with CT and/or CBCT in the planning, execution, or follow-up of dental implant placement and/or bone grafting procedures in the maxilla or the mandible. Included studies were also assessed according to the diagnostic imaging efficacy scale presented by Fryback and Thornbury (F&T). RESULTS: The search strategy yielded 10 studies, which were included in the systematic review. Six studies focused on the implant planning phase, one on the immediate follow-up phase, and three on both planning and follow-up. No studies acquired signal from the bone. There was no consensus on the gold standard, MRI sequence, or field strength (T). One study reached F&T level 1, eight reached level 2, and one reached level 3. CONCLUSION: The possible transition from radiography to ionizing-radiation-free imaging through MRI is still a novelty in dentistry and has yet to establish itself as a viable imaging modality suitable for replacing CT and CBCT. More studies are needed on the accuracy of the diverse MRI possibilities when applied for implant planning, execution, and follow-up before this diagnostic method can be considered as a reality for the clinician.

Prevalence and severity of image-stitching artifacts in charge-coupled device-based cephalograms of orthodontic patients.

OBJECTIVES: The aim of this study was to assess the prevalence and severity of image-stitching artifacts in charge-coupled device (CCD)-based cephalograms and their relationship to patient age. STUDY DESIGN: Cephalograms from 200 patients, acquired by using 2 Promax 2-D units (100 images using Dimax-3 [D-3] and 100 using Dimax-4 [D-4] sensors) were examined. Three observers assessed the presence and severity of image-stitching artifacts for stitching line visibility in 3 categories (none or almost invisible, thin, and thin with vertical stripes or thick) and misalignment between the anatomic structure display in 4 categories (none, <1 mm, 1-3 mm, and >3 mm). Severe artifacts were defined as a stitching line that was thin with vertical stripes or thick, and misalignment ≥1 mm. Patients were grouped by age: ≤13, 14-20, and >20 years old. Observer agreement was assessed by using Kappa statistics. Artifact prevalence and severity were calculated for both sensor types. The effect of age on the presence of severe artifacts was assessed. RESULTS: Stitching lines were observed in 86.7% of D-3 images and 3.3% of D-4 images. Young age had a significant effect on the presence of severe artifacts in D-3 images. CONCLUSIONS: Sensor type and patient age have substantial effects on the prevalence and severity of image-stitching artifacts in CCD-based cephalograms.

Cone beam CT and treatment decision of mandibular third molars: removal vs. coronectomy-a 3-year audit.

OBJECTIVES: To assess: (1) the workflow in the treatment decision process of mandibular third molars based on a panoramic image and CBCT and (2) the impact of radiographic markers in CBCT on the decision to perform coronectomy. METHODS: 1437 teeth in 917 patients (mean age 27.8 years, range 18-72) underwent clinical and panoramic examination. If there was an indication for removal of the tooth, and signs of a close relation to the inferior alveolar nerve were present in the panoramic image, a CBCT was performed. Treatment decision based on panoramic image and CBCT was calculated. Statistical analyses were performed to assess whether signs in CBCT had an impact on the treatment decision "coronectomy". Moreover, the actually operated teeth and post-operative sensory disturbances were assessed and discussed in relation to the radiographic method. RESULTS: Based on the panoramic image, in 462 cases it was decided not to treat, 553 were scheduled for surgery, and 422 referred for a CBCT examination. "No bony separation between the tooth and mandibular canal" seen in CBCT was the main factor influencing the decision to perform a coronectomy (odds ratio = 56.8, p < 0.001). 840 mandibular third molars had undergone surgical intervention, 152 had a coronectomy and 688 were fully removed. Six patients perceived a sensory disturbance of the inferior alveolar nerve: one permanent and five temporary. CONCLUSION: 29% of the examined cases were referred for a CBCT and of these, the majority were scheduled for coronectomy based on the sign "no bony separation between the tooth and mandibular canal" seen in CBCT.

Marginal bone loss and resorption of second molars related to maxillary third molars in panoramic images compared with CBCT.

OBJECTIVES: Compare findings among observers in panoramic images (PAN) and cone beam CT (CBCT); and assess findings in PAN as indicators for marginal bone loss and resorption observed in CBCT. METHODS: 120 impacted maxillary third molars with PAN and CBCT were included. Four observers assessed morphological features: (1) tooth angulation; (2) number of roots; (3) bony impaction (yes/no) and pathology; (4) marginal bone level at the second molar (normal/>3 mm = bone loss); (5) resorption in the second molar (no/superficial/< half way through the dentin/≥ half way through the dentin/involving the pulp); (6) size of follicular space (normal/> 4 mm(cyst)). Percentage accordance and κ statistics described observer variation in PAN and CBCT. Logistic regression analyses tested findings in PAN as indicators for marginal bone loss or resorption observed in CBCT. RESULTS: κ values were fair and interobserver accordance was marginally higher in CBCT than PAN. Agreement between PAN and CBCT was 81-88% for marginal bone loss and 68-81% for resorption. Severe resorption was more often observed in CBCT. Mesio-angulated third molars and marginal bone loss interpreted in PAN significantly indicated marginal bone loss observed in CBCT (odds ration 17-34; p < 0.012; 8.8-52.8; p < 0.02). In contrast, findings in PAN were not significant indicators for resorption observed in CBCT (p > 0.05). CONCLUSION: In general, there was a fair agreement for marginal bone loss between PAN and CBCT, and PAN could significantly predict bone loss observed in CBCT. However, presence of resorption observed in CBCT could not be determined from PAN, and more severe resorption was observed in CBCT. CBCT is indicated if resorption in the second molar needs to be assessed.

Accuracy of detecting and measuring buccal bone thickness adjacent to titanium dental implants-a cone beam computed tomography in vitro study.

OBJECTIVES: The aim of this study was to assess the accuracy of detecting and measuring buccal bone thickness (BBT) adjacent to titanium implants in cone beam computed tomography (CBCT) images. STUDY DESIGN: Titanium implants (1, 2, or 3), abutments, and metal-ceramic crowns were inserted into 40 bone blocks with various BBTs. CBCT images were acquired in various settings: Voxel sizes (0.2 and 0.13 mm) and reconstruction section thicknesses (2.0 and 5.0 mm) were assessed by 3 examiners. True BBT was measured in digital photographs of the bone blocks. Buccal bone detection was evaluated by sensitivity and specificity. BBT was evaluated by 1-way analysis of variance (ANOVA) between the true and the CBCT measurements and by calculating the difference between the true measurement and the CBCT measurement (Di-BBT). RESULTS: Detection of buccal bone exhibited high sensitivity (0.86-1) and low specificity (0.14-1). More implants in the field of view, large voxel size, and thick image reconstruction sections had a negative impact on buccal bone detection. ANOVA showed statistically significantly larger BBT for the CBCT measurements in all settings (1.07-1.21 mm) compared with the true measurements (0.85 mm). Di-BBT was mostly within 0.5 mm. CONCLUSIONS: BBT adjacent to titanium implants is overestimated when evaluated on CBCT cross-sectional images.

Marginal bone level in two Danish cross-sectional population samples in 1997-1998 and 2007-2008.

OBJECTIVE: The aim of this study was to compare the marginal bone level of two randomly selected population samples from 1997/1998 and 2007/2008, with special emphasis on the role of smoking habits and gender. MATERIALS AND METHODS: Two cross-sectional randomly selected population samples [1997/1998 (N = 616) and 2007/2008 (N = 396)] were analysed with respect to the marginal bone level. The marginal bone level was measured in full-mouth intraoral radiographs. Information on smoking was gathered using questionnaires. Multiple regression analysis was used in order to adjust for correlating factors (gender, age, smoking habits and number of teeth). RESULTS: After adjusting for confounding factors, the population sample from 2007/2008 had on average a slightly, but statistically significantly, more reduced average marginal bone level (0.15 mm) than the population sample from 1997/1998. Men had more reduced marginal bone level than women (0.12 mm). Smokers in both population samples had more reduced marginal bone level than non-smokers (0.39 mm and 0.12 mm for 1997/1998; 0.65 mm and 0.16 mm for 2007/2008). CONCLUSIONS: In these populations, sampled 10 years apart, the 2007/2008 population sample had a slightly more reduced marginal bone level than the 1997/1998 population sample. Men had more reduced marginal bone level than women, and smoking is considered a major risk factor for a reduced marginal bone level.

Use of cone beam computed tomography to assess significant imaging findings related to mandibular third molar impaction.

OBJECTIVE: The aim of the study was to identify risk factors for pathoses related to mandibular third molars observed in cone beam computed tomography. STUDY DESIGN: Cone beam computed tomography volumes of 410 mandibular third molars were assessed by 3 observers, according to the angulation and position of the third molar in relation to the second molar. In addition, pathoses (marginal bone loss, resorption of the second molar, increased follicular space and lingual bone perforation) were assessed. Logistic regression analyses were used to test whether the angulation and position of the third molar were risk factors for pathoses. RESULTS: On average, 41% of second molars had resorption; mesioangulated (odds ratio [OR] 11-107; P < .001) and horizontally positioned (OR 13-120; P < .001) third molars located cervically at the second molar (OR 2-3; P < .027) significantly increased the risk. On average, 49% of second molars had marginal bone loss; mesioangulated (OR 16-85; P < .001) and horizontally positioned (OR 61-573; P < .001) third molars increased the risk. For the third molar, an increased follicular space was seen in 25% of cases; distal (OR 5-9; P < .001) and vertical positions (OR 5; P < .002) increased the risk. Lingual bone perforation was not related to a specific angulation. CONCLUSIONS: Specific angulations of the mandibular third molar are risk factors for marginal bone loss and resorption of the second molar.

Diagnostic validity of periapical radiography and CBCT for assessing periapical lesions that persist after endodontic surgery.

OBJECTIVES: Traditionally, healing after surgical endodontic retreatment (SER); i.e. apicectomy with or without a retrograde filling, is assessed in periapical radiographs (PR). Recently, the use of cone beam CT (CBCT) has increased within endodontics. Generally, CBCT detects more periapical lesions than PR, but basic research on the true nature of these lesions is missing. The objective was to assess the diagnostic validity of PR and CBCT for determining inflammation in SER cases that were re-operated (SER-R) due to unsuccessful healing, using histology of the periapical lesion as reference for inflammation. METHODS: Records from 149 patients, receiving SER 2004-10, were screened. In total 108 patients (119 teeth) were recalled for clinical follow-up examination, PR and CBCT, of which 74 patients (83 teeth) participated. Three observers assessed PR and CBCT as "successful healing" or "unsuccessful healing" using Rud and Molven's criteria. SER-R was offered to all non-healed teeth with expected favourable prognosis for subsequent functional retention. During SER-R, biopsy was performed and histopathology verified whether or not inflammation was present. RESULTS: All re-operated cases were assessed non-healed in CBCT while 11 of these were assessed successfully healed in PR. Nineteen biopsies were examined. Histopathologic diagnosis revealed 42% (teeth = 8) without periapical inflammation, 16% (teeth = 3) with mild inflammation and 42% (teeth = 8) with moderate to intense inflammation. A correct diagnosis was obtained in 58% with CBCT (true positives) and 63% with PR (true positives+true negatives). CONCLUSIONS: Of the re-operated teeth, 42% had no periapical inflammatory lesion, and hence no benefit from SER-R. Not all lesions observed in CBCT represented periapical inflammatory lesions.

Accuracy of video observation and a three-dimensional head tracking system for detecting and quantifying robot-simulated head movements in cone beam computed tomography.

OBJECTIVES: To assess the accuracy of detecting robot-simulated head movements using video observation (VO) and 3-dimensional head tracking (HT) in a cone beam computed tomography examination setup. STUDY DESIGN: A mannequin head was mounted on a robot that was programmed to simulate patient head movements. Six types of movement (tremor, nodding, lateral rotation, lifting, swallowing, and anteroposterior translation), 3 distances (0.25, 1, and 5 mm), and 2 speeds (1 and 5 mm/s) were tested in triplicate (108 examinations). An additional 18 videos and HT of no-motion served as controls for a total of 126 examinations. Three blinded observers viewed video recordings of the examinations, scoring whether the head moved and the movement type. HT provided quantitative measures of movement distance. Accuracy, sensitivity, and specificity for movement detection by VO and HT were calculated, related to true type, distance, and speed of movement. Differences between the true and the measured movement distances were assessed for HT. RESULTS: VO movement detection presented accuracy of 0.86, sensitivity of 0.85, and specificity of 0.94. Anteroposterior translation (33.3%) and 0.25 mm movements (41.7%) were often not detected by VO. HT correctly detected all cases (accuracy = 1). HT presented small differences between the true and the measured movement distances (average 20-54 µm). CONCLUSIONS: VO missed 41.7% of the 0.25 mm movements. HT correctly detected all movements and quantified movements with an average error <55 µm.

The impact of smoking on marginal bone loss in a 10-year prospective longitudinal study.

OBJECTIVES: The aim of this epidemiologic study was to determine the impact of smoking on marginal bone loss in a subsample derived from an original randomly selected adult sample, after adjusting for oral and general factors. METHODS: The number of participants at baseline in this 10-year longitudinal study was 616 (mean age: 42 years, range 21-63 years). The participants underwent a full-mouth radiographic survey. After recall in 2003, 473 (77%) of the participants accepted and completed an identical survey. In 2008, the survey was repeated, and 301 (48.9%) individuals were included in this study. The marginal bone level of each tooth was measured in mm. Age, gender, smoking habits, number of teeth, apical periodontitis, crowns and initial marginal bone level were also recorded for each individual. Only individuals who did not report a change in smoking habits during the 10-year period were included in the study. Multiple regression analyses were used to evaluate crude and adjusted associations between smoking and marginal bone loss. RESULTS: At the first, radiographic survey smokers had a statistically significantly more reduced marginal bone level (in average 0.9 mm) than nonsmokers. After 10 years, a progression of a mean marginal bone loss of > 2 mm was statistically significantly more common in smokers than in nonsmokers (7.1% and 0%, respectively). Furthermore, a marginal bone loss of 1-2 mm was observed in 29% of the smokers and 19% of the nonsmokers, and ≤ 1 mm marginal bone loss was found in 69% of smokers and 81% of nonsmokers. Even after adjusting for initial marginal bone level, gender, age, and also presence of apical periodontitis and crowns, the difference in progression of marginal bone loss was still statistically higher in smokers (on average 0.36 mm). CONCLUSIONS: The smokers started out with a more reduced marginal bone level than nonsmokers. However, even after adjusting for the initial marginal bone level, the progression of marginal bone loss in smokers was more pronounced than in nonsmokers. This shows that smoking is a factor with significant impact on the marginal bone level and can be assumed to be a true risk factor for marginal bone loss.

Factors affecting the possibility to detect buccal bone condition around dental implants using cone beam computed tomography.

OBJECTIVES: To evaluate factors with impact on the conspicuity (possibility to detect) of the buccal bone condition around dental implants in cone beam computed tomography (CBCT) imaging. MATERIAL AND METHODS: Titanium (Ti) or zirconia (Zr) implants and abutments were inserted into 40 bone blocks in a way to obtain variable buccal bone thicknesses. Three combinations regarding the implant-abutment metal (TiTi, TiZr, or ZrZr) and the number of implants (one, two, or three) were assessed. Two CBCT units (Scanora 3D - Sc and Cranex 3D - Cr) and two voxel resolutions (0.2 and 0.13 mm) were used. Reconstructed sagittal images (2.0 and 5.0 mm thickness) were evaluated by three examiners, using a dichotomous scale when assessing the condition of the buccal bone around the implants. A multivariate logistic regression was performed using examiners' detection of the buccal bone condition as the dependent variable. Odds ratio (OR) were calculated separately for each CBCT unit. RESULTS: Implant-abutment combination (ZrZr) (OR Sc = 19.18, OR Cr = 11.89) and number of implants (3) (OR Sc = 12.10, OR Cr = 4.25) had major impact on buccal bone conspicuity. The thinner the buccal bone, the higher the risk that the condition of the buccal bone could not be detected. The use of lower resolution protocols increased the risk that buccal bone was not properly detected (OR Sc = 1.46, OR Cr = 2.00). For both CBCT units, increasing the image reconstruction thickness increased the conspicuity of buccal bone (OR Sc = 0.33, OR Cr = 0.31). CONCLUSIONS: Buccal bone conspicuity was impaired by a number of factors, the implant-abutment material being the most relevant. Acquisition and reconstruction factors had minor impact on the detection of the buccal bone condition.

Patient movement and motion artefacts in cone beam computed tomography of the dentomaxillofacial region: a systematic literature review.

OBJECTIVES: To undertake a systematic review on the current knowledge regarding patient movement detection and patient motion artefacts related to cone beam computed tomography (CBCT) imaging of the dentomaxillofacial region. METHODS: The MEDLINE (PubMed) bibliographic database was searched for a period up to June 2015 for studies evaluating patient movement and/or motion artefacts in CBCT. The search strategy was restricted to English language publications using the following combined terms: (movement OR motion) AND (CBCT OR cone beam CT). RESULTS: The search strategy yielded eight publications, which qualitatively or quantitatively evaluated patient movement and/or patient motion artefacts in CBCT. CONCLUSIONS: The literature suggests that patient movement usually presents itself in CBCT images as stripe-like and ring-like patterns, double bone contours, and overall lack of sharpness. Studies monitoring patients during CBCT examination reported a prevalence of movement in approximately 20% of the cases, and studies based on image artefact recognition to define patient movement reported prevalence as high as 41.5%. There seems to be a consensus on the fact that young patients (children and adolescents) often move during the examination.

Periapical Bone Healing after Apicectomy with and without Retrograde Root Filling with Mineral Trioxide Aggregate: A 6-year Follow-up of a Randomized Controlled Trial.

INTRODUCTION: In cases of post-treatment periapical disease, retreatment may be necessary. To choose the most appropriate retreatment method, knowledge of the long-term prognosis is important. Surgical endodontic retreatment (SER) is a relevant treatment method. This study assessed changes in outcome from 1 to 6 years after surgery. METHODS: SER was performed on teeth randomly allocated to have a MTA root-end filling (MTA group) or smoothing of the orthograde gutta-percha filling after apicectomy (GP group). Patients participating in the 1-year follow-up were reinvited for a 6-year clinical and radiographic examination. Three observers assessed treatment outcome both clinically and radiographically from the 1-year and 6-year follow-up examination. RESULTS: At the 6-year follow-up, 39 of 52 teeth were available and examined (75% participation rate). In the MTA group, 16 of 19 teeth (86%) and in the GP group 11 of 20 teeth (55%) were assessed as successful (P = .04). In the MTA group and the GP group, 80% and 90%, respectively, of teeth assessed as successful at the 1-year follow-up remained successful. All unsuccessful teeth in the MTA group (3 teeth) were lost because of vertical root fracture. CONCLUSIONS: The proportion of healed cases was larger in the MTA group than in the GP group at both the 1-year and 6-year follow-up. Findings indicate that a 1-year follow-up may not be sufficient in assessing the long-term outcome of surgical endodontic retreatment. With a longer follow-up, other factors not directly related to the endodontic treatment may be relevant for a successful outcome. This needs further investigation in larger patient samples.

Diagnostic accuracy of cone beam computed tomography sections with various thicknesses for detecting misfit between the tooth and restoration in metal-restored teeth.

OBJECTIVE: To evaluate the diagnostic accuracy of cone beam computed tomography (CBCT) sections with various reconstruction thicknesses for detecting misfit between tooth and restoration in metal-restored teeth. STUDY DESIGN: Eighty teeth (perfect fit, 40 of these used with 0.2 mm gap, and 40 with 0.4 mm gap), were imaged with large FOV i-CAT. Images were reconstructed in five thicknesses: 0.2 (voxel size), 1, 2, 5, and 10 mm. Four examiners assessed the presence of gaps using a 5-point scale. Area under the receiver operating characteristics curve (aucROC) for misfit detection was calculated for each variable. A multivariate logistic regression was performed by using misfit detection accuracy as the dependent variable. RESULTS: The score "cannot decide" decreased when the reconstruction thickness was increased. Mean aucROC ranged between 0.60 and 0.72. Logistic regression showed that the presence of a gap and reconstruction thickness had an impact on diagnostic accuracy. CONCLUSIONS: Diagnostic accuracy of CBCT sections was low for detecting misfit in metal-restored teeth.

Factors affecting patient movement and re-exposure in cone beam computed tomography examination.

OBJECTIVE: To assess operator-, examination-, and patient-related factors, affecting patient movement and re-exposure in cone beam computed tomography (CBCT) examination. STUDY DESIGN: The sample consisted of 248 CBCT examinations in 190 patients video-recorded during examination. Three observers scored the videos; the patient moved or did not move. Operator-, examination-, and patient-related factors were evaluated separately (chi-square test) and by multivariate regression analyses (patient movement and re-exposure as separate outcomes). RESULTS: The prevalence of movement was 21%. Cotton roll stabilizing patient's jaws, CBCT unit touching patient's hair, and patient's age 15 years or greater were related to movement. Age 15 years or greater had a significant impact on movement (P < .001; odds ratio [OR] 11.0). There were 16 re-exposures (6.4%). Age 15 years or greater, presence of a cotton roll, and field of view (FOV) were related to re-exposure. Use of a large FOV had significant impact on re-exposure (P = .04; OR 5.8). CONCLUSIONS: Operator-, examination-, and patient-related factors may affect patient movement and re-exposure in CBCT examination.

Fate of the buccal bone at implants placed early, delayed, or late after tooth extraction analyzed by cone beam CT: 10-year results from a randomized, controlled, clinical study.

AIM: To present 10-year cone beam CT (CBCT) data on the fate of buccal bone at single-tooth implants placed early, delayed, or late after tooth extraction. MATERIAL AND METHODS: Sixty-three of 72 patients, originally randomly allocated to three equal-size groups, received a single-tooth implant on average 10 days (Ea; N = 22), 3 months (De; N = 22), or 1.5 years (La; N = 19) after tooth extraction. Healing abutments were mounted after a 3-month period of submerged healing and metalceramic crowns were cemented after one additional month. At the second stage surgery, presence of buccal bone defects (dehiscences or intrabony) and their dimensions were registered. CBCT scans recorded with a Scanora(®) 3D unit and standardized periapical (PA) radiographs of the implants were obtained at the 10-year control. Interproximal bone levels (i.e., the distance from the implant platform to the first bone-to-implant contact; BIC) measured in CBCT image sections and PA were compared, and the buccal bone level was determined in the CBCT images. RESULTS: Two Ea and one De implants failed to osseointegrate. Forty-nine patients attended the 10-year control and due to poor quality of 5 CBCT scans, useful CBCT images were available from 44 patients (Ea:12, De:17, La:15). No significant differences between CBCT and PA images in measurements of the interproximal bone levels were observed. Ten years after implant placement, BIC at the buccal aspect was located on average 2 mm apically to the implant platform (2.39 ± 1.06 mm [median = 2.36] for Ea, 2.22 ± 0.99 mm [median = 2.16] for De, and 1.85 ± 0.65 mm [median = 1.95] for La implants) with no significant difference among the groups (P = 0.20). Mean buccal bone level (bBL) for implants with an intrabony or a dehiscence defect at second stage surgery was 2.51 ± 1.12 mm [median = 2.70] and 2.84 ± 0.70 mm [median = 2.79], respectively, while 1.78 ± 0.74 mm [median = 1.93] for the implants with no defect. The difference in bBL between the implants without a defect and those with a dehiscence was significant at 10 years (P = 0.0005). CONCLUSION: Time of placement of single-tooth implants after tooth extraction did not significantly influence the peri-implant buccal bone level, while presence of a buccal bone dehiscence at second stage surgery resulted in significantly more apically located BIC buccally at 10 years.

Remodeling of cortical and corticocancellous fresh-frozen allogeneic block bone grafts--a radiographic and histomorphometric comparison to autologous bone grafts.

OBJECTIVES: To compare cortical (AL-C) and corticocancellous (AL-CC) fresh-frozen block bone allografts to cortical block bone autografts (AT) used for lateral ridge augmentation in terms of radiographic dimensional maintenance and histomorphometrical graft remodeling. MATERIALS AND METHODS: Twenty-four patients, requiring ridge augmentation in the anterior maxilla prior to implant placement, were treated with AT, AL-C or AL-CC bone blocks (eight patients per graft type). Patients were examined with CBCT prior to, 14 days, and 6-8 months after grafting. Amount of augmentation and dimensional block graft maintenance over time was evaluated by comparing planimetric measurements of the alveolar ridge made on CBCT sections of the augmentation area. During implant installation surgery, 6-8 months after grafting, cylindrical biopsies were harvested perpendicularly to the lateral aspect of the augmented alveolar ridge. The relative volumes of vital and necrotic bone and soft tissues were histomorphometrically estimated. Comparisons among groups and observation times were performed using Friedman test followed by Dunn's post-hoc test. RESULTS: Radiographic evaluation showed that the three types of grafts resulted in a significant increase in alveolar ridge width, with no significant differences among the groups in terms of ridge dimensions at the various observation times. However, significant graft resorption (P = 0.03) was observed in the AL-CC group over time (-8.3 ± 7.1%) compared with the AT and AL-C groups, where a slight increase was observed, on average (1.5 ± 20.6% and 1.3 ± 14.9%, respectively). Histomorphometrical analysis showed that larger amounts of vital bone were found in the biopsies from the AT augmented sites (25.1 ± 11.2%) compared with AL-CC and AL-C augmented sites (9.3 ± 3.8% and 3.9 ± 4.6%, respectively; P ≤ 0.01). AL-CC and AT biopsies had the smallest amount of necrotic bone (38.2 ± 12.1% and 56.7 ± 26.0, respectively) compared with AL-C (83.7 ± 10.8%, P < 0.01) biopsies. AL-CC biopsies showed the largest amount of soft tissues (52.5 ± 11.7%) compared with those from AT (18.1 ± 17.1%, P = 0.03) and AL-C (12.3 ± 8.5%, P < 0.01) sites. CONCLUSIONS: AL block bone graft architecture influences significantly its dimensional incorporation and remodeling. Compared with AT bone graft, a small portion of the AL block consists of vital bone 6-8 months after grafting. Cortical AL blocks seem to show the least amounts of vital bone, while corticocancellous AL blocks seem to undergo more resorption over time.

Early, delayed, or late single implant placement: 10-year results from a randomized controlled clinical trial.

AIM: The aim of this study was to present the 10-year clinical and radiographic data from a RCT on single-tooth implants placed early, delayed, or late after tooth extraction. MATERIALS AND METHODS: Sixty-three patients were randomly allocated to three groups and received an implant on average 10 days (Ea), 3 months (De), or 17 months (La) after tooth extraction. Second-stage surgery was performed after 3 months of submerged healing; metal-ceramic crowns were cemented after one additional month. Standardized periapical radiographs were taken 1 week after implant placement (TP), 1 week (TC) and 1-1.5 year (T1) after crown delivery, and 10 years after implant placement (T10). Pocket depth (PD) and bleeding on probing were registered during controls (TC - T10). RESULTS: Two Ea and one De implants failed to osseointegrate. Seven patients (4 Ea, 1 De, and 2 La) were not available at T10 . No significant differences were found among groups regarding implant survival or radiographic peri-implant marginal bone levels (Ea: 1.15 ± 0.77; De: 1.53 ± 1.06; La: 1.42 ± 1.07) at T10 . Similarly, no differences were observed among groups in the number of implants with PD ≥ 5 mm (Ea: 29%; De: 35%; La: 44%) or the average depth of the sites with PD ≥ 5 mm (Ea: 5.4 ± 0.7; De: 6.1 ± 1.4; La: 5.4 ± 0.5) at T10 . Peri-implant mucositis was found in 70% of the cases; peri-implantitis was diagnosed only in two implants (1 De, 1 La) corresponding to 4.3%. CONCLUSION: Single-tooth implants placed early or delayed after tooth extraction show high survival rates and limited peri-implant marginal bone resorption or biological complications, similar to what is observed with implants placed according to the conventional (late) protocol.