A comparison of peripheral marginal bone loss at dental implants measured with conventional intraoral film and digitized radiographs

Accuracy of high-resolution ultrasound (US) for gingival soft tissue thickness mesurement in edentulous patients prior to implant placement

OBJECTIVES

To evaluate and compare the accuracy of high-resolution ultrasound (US) with two different cone beam CT (CBCT) units and clinical assessment for measuring gingival soft tissue thickness in edentulous patients prior to implant placement.

METHODS AND MATERIALS

The study consisted of 40 maxillary implant sites of 40 healthy patients (20 females, 20 males; mean age, 47.88 years). We prospectively evaluated labial/buccal gingival thickness in 40 implant regions (16 anterior and 24 posterior) by using limited field of view (FOV) CBCT images and US images in comparison to gold standard transgingival probing measurements. One-way analysis of variance (ANOVA) was used to compare mean measurements obtained from CBCT (Morita and Planmeca), US, and transgingival probing. Interclass correlation coefficient (ICC) estimates were calculated based on means with two-way mixed and absolute-agreement model. Bland Altman plot was used to describe agreement between clinical vs US and CBCT measurements by constructing limits of agreement. Statistical significance was set at p < 0.05.

RESULTS

There was no significant difference between methods used according to mean gingival thickness measurements obtained from the top (p = 0.519) and bottom (p = 0.346) of the alveolar process. US and CBCT measurements highly correlated with clinical measurements for both top and bottom alveolar process gingival thickness (p < 0.001). Distribution of differences between clinical measurements and both CBCT measurements showed statistically significant differences according to 0 (p < 0.05). Distribution of differences between clinical measurements and US measurements did not show statistically significant difference (p > 0.05).

CONCLUSION

High-resolution US provided accurate information for the measurement of gingival soft tissue thickness in edentulous patients prior to implant placement.

Efficacy of Periapical Radiography and Three Cone-Beam Computed Tomography Systems for Detection of Peri-Implant Dehiscence Defects: An in- Vitro Study

Background:

Early detection of peri-implant bone defects is highly important because these defects eventually lead to gingival recession, bone loss and implant failure.

Objective:

This study aimed to assess and compare the efficacy of periapical radiography and three CBCT systems for the detection of peri-implant dehiscence defects.

Material and Methods:

In this vitro study, 124 titanium implants were placed in bovine ribs. The bone pieces were then mounted in boxes in the form of mandible and red dental wax was used to simulate the soft tissue. Crestal bone defects with 2, 3, and 4 mm depth were created in the ribs using a round bur. Periapical and CBCT images were then obtained. Images were investigated by two oral and maxillofacial radiologists twice with a two-week interval. The results were analyzed using chi-square, Kappa coefficient, Cochrane’s Q and McNemar tests as well as the receiver operating characteristic (ROC) curve.

Results:

The two observers showed good agreement in detection of sound and defective samples on periapical radiographs and CBCT scans. The level of agreement was low in detection of two samples with 2 mm defects on CBCT scans taken with Planmeca and NewTom 3G systems at the time of second assessment. NewTom 3G had the highest sensitivity (68.9%, 74.2% and 86.3%, respectively) and specificity (100% for all three) compared to other systems for detection of 2, 3 and 4 mm crestal bone defects.

Conclusion:

The inter-observer agreement increased with increase in depth of defects. NewTom 3G had the highest accuracy for detection of crestal bone defects.

Etiology and Measurement of Peri-Implant Crestal Bone Loss (CBL)

The etiology of peri-implant crestal bone loss is today better understood and certain factors proposed in the past have turned out to not be of concern. Regardless, the incidence of crestal bone loss remains higher than necessary and this paper reviews current theory on the etiology with a special emphasis on traditional and innovative methods to assess the level of crestal bone around dental implants that will enable greater sensitivity and specificity and significantly reduce variability in bone loss measurement.

Changes in alveolar bone density around immediate functionally and nonfunctionally loaded implants

STATEMENT OF PROBLEM

Few studies compare the radiographic changes in bone density associated with immediate implant loading protocols.

PURPOSE

The purpose of this longitudinal study was to quantitatively assess radiographic changes in alveolar bone density around immediate functionally and nonfunctionally loaded implants.

MATERIAL AND METHODS

A prospective longitudinal study was conducted in which 20 participants with partially edentulous mandibles received implants that were immediately loaded either functionally (IFL) or nonfunctionally (INFL). Standardized intraoral periapical radiographs were made at baseline, 3, and 6 months. These were digitized and analyzed using the histogram tool of the GNU Image Modulation Program for changes in alveolar bone density at crestal and lateral apical levels around the implant.

RESULTS

An increase in the mean lateral apical pixel grayscale values of 4.68 ±0.80 at 3 months and 4.15 ±0.29 at 6 months was observed with IFL, while INFL demonstrated an increase of 5.66 ±0.53 at 3 months and 6.07 ±0.59 at 6 months. A decrease in the mean crestal pixel grayscale values of -24.40 ±7.41 with IFL and -16.86 ±5.14 with INFL was found from baseline to 3 months.

CONCLUSIONS

On the basis of this longitudinal study, it was concluded that immediate loading stimulated alveolar bone formation at 6 months after implant placement. The immediate functional loading of implants resulted in a significantly greater degree of bone demineralization at the alveolar crest from implant placement up to 3 months compared with immediate nonfunctional loading.

Accuracy of CBCT images in the assessment of buccal marginal alveolar peri-implant defects: effect of field of view

OBJECTIVES

To investigate the reliability and accuracy of cone beam CT (CBCT) images obtained at different fields of view in detecting and quantifying simulated buccal marginal alveolar peri-implant defects.

METHODS

Simulated buccal defects were prepared in 69 implants inserted into cadaver mandibles. CBCT images at three different fields of view were acquired: 40 × 40, 60 × 60 and 100 × 100 mm. The presence or absence of defects was assessed on three sets of images using a five-point scale by three observers. Observers also measured the depth, width and volume of defects on CBCT images, which were compared with physical measurements. The kappa value was calculated to assess intra- and interobserver agreement. Six-way repeated analysis of variance was used to evaluate treatment effects on the diagnosis. Pairwise comparisons of median true-positive and true-negative rates were calculated by the χ² test. Pearson's correlation coefficient was used to determine the relationship between measurements. Significance level was set as p < 0.05.

RESULTS

All observers had excellent intra-observer agreement. Defect status (p < 0.001) and defect size (p < 0.001) factors were statistically significant. Pairwise interactions were found between defect status and defect size (p = 0.001). No differences between median true-positive or true-negative values were found between CBCT field of views (p > 0.05). Significant correlations were found between physical and CBCT measurements (p < 0.001).

CONCLUSIONS

All CBCT images performed similarly for the detection of simulated buccal marginal alveolar peri-implant defects. Depth, width and volume measurements of the defects from various CBCT images correlated highly with physical measurements.

Immediate placement and loading of maxillary single-tooth implants: a 3-year prospective study of marginal bone level

AIM

The purpose of this study was to evaluate marginal bone level around single-tooth implants placed in anterior maxilla and immediately restored.

MATERIALS AND METHODS

Twenty implants were placed in 20 patients (8 men and 12 women) that were selected for this study. Following atraumatic non-surgical extraction of tooth, all patients immediately received implants and the definitive prefabricated abutment was placed. Implant position was transferred to the scanning unit of the CAD/CAM system using prefabricated surgical guide. Temporary crowns were immediately fabricated and cemented. Eight weeks later final crowns were luted. Outcome assessment as implant survival and level of marginal bone radiographic evaluations were performed at 8 weeks, 1 and 3 years time period after loading.

RESULTS

All implants placed osseointegrated successfully after 3 years of functional loading. The mean marginal bone loss was 0.16 mm (SD, 0.167 mm), 0.275 mm (SD, 0.171 mm) and 0.265 mm (SD, 0.171 mm) at 8 weeks, 1 and 3 years time period respectively. Four out of the 20 implants showed no bone loss.

CONCLUSION

Immediate loading technique using the final abutment directly eliminated the need for a second stage surgery and prevented interruption of soft and hard tissue at implant neck, which resulted in better soft tissue response and reduced marginal bone loss. Clinical significance: Immediately loaded implants, in fresh extraction sockets by insertion of a provisional restoration on the titanium abutment without any later manipulation, helped to protect the initially forming blood clot and presented a template for soft tissue contouring that resulted in significant reduction of marginal bone resorption and maintenance of soft tissue architecture.

Assessment of buccal marginal alveolar peri-implant and periodontal defects using a cone beam CT system with and without the application of metal artefact reduction mode

OBJECTIVES

To investigate the accuracy of cone beam CT (CBCT) images obtained with and without artefact reduction (AR) in detecting simulated buccal peri-implant and buccal periodontal defects.

METHODS

42 implants inserted into edentulous mandibles, and 38 teeth present in dry mandibles were used. Simulated buccal peri-implant defects (n = 22) and buccal periodontal defects (n = 22) were prepared. 20 implants and 18 teeth without simulated defects were the control group. Images of the mandibles were obtained using a Planmeca ProMax(®) 3D Max CBCT unit (Planmeca Oy, Helsinki, Finland). Image reconstructions were prepared without and with low, medium and high AR modes. Images were viewed randomly by six observers twice for the presence of defects. Kappa coefficient was calculated. F2_LD_F1 design for non-parametric analysis of longitudinal data was used. Area under curves (AUCs) were calculated for each observer. Significance level was taken as α = 0.05.

RESULTS

Intraobserver kappa ranged from 0.140 to 0.792 for peri-implant and from 0.189 to 1.0 for periodontal defects. All factors were statistically significant (p < 0.001), except for image mode and implant brand. Pairwise interactions were found between periodontal defects and peri-implant defects (p < 0.001), observers (p < 0.001), observer and image mode (p < 0.001), defect model and observer (p < 0.001) and defect model, image mode and observer (p = 0.04). AUC values ranged from 0.39 to 0.52 for peri-implant and from 0.45 to 0.71 for periodontal defects. Higher AUC values were found for periodontal defects than for peri-implant defects.

CONCLUSIONS

Buccal peri-implant defects were more difficult to detect than buccal periodontal defects. No difference was found among CBCT images obtained with and without AR modes.

A method for segmentation of dental implants and crestal bone

PURPOSE

Medical imaging and in particular digital radiographic images offer a great deal of information to dentists in the clinical diagnosis and treatment processes on a daily basis. This paper presents a new method aimed to produce an accurate segmentation of dental implants and the crestal bone line in radiographic images. With this, it is possible computing several measures to biomechanical and clinical evaluation of dental implants positioning and evolution.

METHODS

The proposed segmentation method includes two major steps: (1) the preprocessing that combine denoising filters, morphological operations and histogram threshold techniques and (2) the final segmentation involving made-to-measure adjusted and trained active shape models for detecting the precise location of the intended structures.

RESULTS

Resulting measurements were compared to manual measurements made by experts on representative radiographs from patients. The calculated intraclass correlation coefficient was 0.75 and showed good reliability of the method, and the Bland-Altman analysis showed 95% of the values within the limits of agreement. The mean of the differences between the manual and method-driven measurements was 0.049 mm ([Formula: see text]) 95% CI, inferior to the established limit (0.15mm).

CONCLUSIONS

It was demonstrated that the method achieved a precise segmentation of the intended structures. The validation process on standardized periapical radiographs showed good agreement between the manual measurements and the ones produced by the new method. Future work will be focused on making the method more robust to densitometry changes and to validate the method on non-standardized radiographs.