Computer planning and bone density evaluation of jaws reconstructed with bone grafts from living donors.

Bone augmentation to reconstruct atrophic jaws provides the base for sufficient functional and aesthetic implant-supported oral rehabilitation. Although autografts are the standard procedure for bone grafting, the use of homolog bone provides a reasonable alternative because it is safe, cheap, and available in adequate amount. Five patients were grafted with femur bone derived from living donors, and in 2 of them, 16 implants were inserted after 6 months. Pearson χ test was used to investigate the difference in bone density (BD) between native and grafted bone and between peri-implant and bone far from fixtures. The BD of the grafted bone is about double that of the native bone. Peri-implant BD is higher than BD far from fixtures, demonstrating that implant loading increase BD. Computed tomography is a valuable and accurate preoperative and follow-up method to obtain information about bone quality and quantity (ie, volume of available bone). Femur graft has a high density that improves under loading, thus suggesting that early implant loading should be performed whenever possible. However, a larger implant series and a longer observation period are mandatory to have a stronger support to these preliminary data.

Maxillary sinus augmentation using recombinant bone morphogenetic protein-2/acellular collagen sponge in combination with a mineralized bone replacement graft: a report of three cases.

The objective of the following case reports was to assess whether mineralized bone replacement grafts (eg, xenografts and allografts) could be added to recombinant human bone morphogenetic protein-2/acellular collagen sponge (rhBMP-2/ACS) in an effective manner that would: (1) reduce the graft shrinkage observed when using rhBMP-2/ACS alone, (2) reduce the volume and dose of rhBMP-2 required, and (3) preserve the osteoinductivity that rhBMP-2/ACS has shown when used alone. The primary outcome measures were histomorphometric analysis of vital bone production and analysis of serial computed tomographic scans to determine changes in bone graft density and stability. Over the 6-month course of this investigation, bone graft densities tended to increase (moreso with the xenograft than the allograft). The increased density in allograft cases was likely the result of both compression of the mineralized bone replacement graft and vital bone formation, seen histologically. Loss of volume was greater with the four-sponge dose than the two-sponge dose because of compression and resorption of the sponges. Vital bone formation in the allograft cases ranged from 36% to 53% but, because of the small sample size, it was not possible to determine any significant difference between the 5.6 mL (four-sponge) dose and the 2.8 mL (two-sponge) dose. Histology revealed robust new woven bone formation with only minimal traces of residual allograft, which appeared to have undergone accelerated remodeling or rhBMP-2-mediated resorption.

A Novel Approach to Bone Reconstruction: The Wafer Technique.

This study presents a novel technique based on guided bone regeneration and onlay grafts for three-dimensional bone augmentation. This two-stage technique uses an autogenous cortical bone plate and collagen membranes to form a barrier containing a mixture of deproteinized bovine bone matrix, autologous blood, and bone grafted from intraoral sites. Five patients were treated. At 6 months postsurgery, a mean increase in bone volume of 1,062 mm³ was shown. Mean maximum linear augmentation was 3.65 mm. Histologic analysis of the regenerated areas revealed the presence of compact newly formed bone with no sign of inflammation. A total of 13 implants were placed. The patients were satisfied, and complications were not observed.

Evaluation of a Novel Cone Beam Computed Tomography Scanner for Bone Density Examinations in Preoperative 3D Reconstructions and Correlation with Primary Implant Stability.

BACKGROUND: Bone density examination (BDE) using preoperative cone beam computed tomography (CBCT) might be used to predict primary implant stability in implant patients. PURPOSE: The aim of the study was to validate a novel CBCT scanner in vitro with regard to BDE in preoperative scans and to analyze the in vivo correlation of CBCT scan results with primary implant stability measurements. MATERIALS AND METHODS: A CBCT scanner was validated in vitro with regard to spatial uniformity and linearity of CT numbers (Hounsfield units, HU) by using a series of phantoms and plastic and hydroxyapatite specimens of various densities. Forty-nine patients (27 female and 22 male, mean age 55.6 ± 9.8) were scanned prior to and 1 to 6 months after the placement of 155 dental implants of different lengths and diameters. Mean and peak insertion torque (IT) in Ncm were registered during implant placement. Resonance frequency analysis (RFA) measurements in ISQ units were performed after placement. The second scan was used to export and superimpose the exact positions of bone and implants into the first scan. Virtual probes with the same length as the actual implant were automatically placed at the implant sites, and mean HU values were measured in a 1 mm-wide circular corridor from the tip of the threads and out. RESULTS: The in vitro validation showed high uniformity and linearity of CT numbers (HU). The clinical study showed significant correlations between bone density and ISQ, mean IT, and peak IT, respectively. CONCLUSIONS: The WhiteFox CBCT scanner measures bone density with high accuracy. There is a correlation between bone density and primary implant stability as assessed with IT and RFA measurements. The findings suggest that BDE may be used as an additional feature in treatment-planning software to estimate primary stability at predetermined implant sites.

Fence technique for localized three-dimensional bone augmentation: a technical description and case reports.

This study presents a novel bone reconstructive technique based on guided bone regeneration for localized three-dimensional hard tissue augmentation. This two-stage technique utilized a titanium osteosynthesis plate and a collagen membrane to form a physical barrier resembling a fence that contains bone graft biomaterial composed of a combination of deproteinized bovine bone matrix and autologous bone grafted from intraoral sites. Six patients were treated. At 6 months postsurgery, an increase in bone volume of 953 mm³ was shown. Mean maximum linear augmentation in the vertical direction was 6.75 mm. Histologic analysis of the regenerated area revealed the presence of compact newly formed bone with no sign of inflammation. A total of 13 implants were placed. Peri-implant marginal bone level was 0.94 mm at implant placement and 1.30 mm after 6 months. The patients were satisfied with the procedure and no complications were observed.

Quantitative comparison of cone beam computed tomography and microradiography in the evaluation of bone density after maxillary sinus augmentation: a preliminary study.

PURPOSE: Cone beam computed tomography (CBCT) and microradiographic analyses were comparatively performed in maxillary sinus augmentation to preliminarily verify the diagnostic potential of CBCT on the evaluation of bone regeneration. MATERIALS AND METHODS: A two-stage protocol was conducted in 19 consenting patients, all having the crestal bone ≤2 mm, in private dental office. Mineralized human bone allograft particles were used to augment sinus using lateral window approach. A succession of CBCT scans of the maxilla was taken before surgery, after sinus augmentation, and immediately after implant insertion. Using virtual probes, CBCT data were processed by medical imaging software and expressed as gray level (GL). A bone core biopsy was taken at implant placement, 6 months after surgery. Microradiography of transverse sections, taken 6, 8, and 10 mm from the crestal surface, of methacrylate-embedded biopsies was performed to analyze and to evaluate the mineralized material amount (MM%). RESULTS: A total of 21 sinus augmentations were performed. CBCT (mean GL: 646-693) data were not statistically different when comparing 6-, 8-, and 10-mm sites to after grafting/implant-insertion values. Furthermore, microradiographic (mean MM%: 45.3-48.3) data were not statistically different comparing 6-, 8-, and 10-mm sites, due to variation of values among patients. A GL and MM% parallelism was identified considering each patient, instead. A significant correlation (p < .001) between GL and MM% was found after both Wilcoxon test for paired data and simple linear regression analysis. CONCLUSIONS: The preliminary result clearly demonstrated the predictability of the CBCT analysis. Due to the limited sample and great variations of the MM% recorded in patients, further clinical and morphometric studies are needed to fulfill diagnostic expectations.

Implant-buccal plate distance as diagnostic parameter: a prospective cohort study on implant placement in fresh extraction sockets.

BACKGROUND: The aim of this study is to investigate contour changes around immediate implants in fresh extraction sockets when different grafting procedures are performed, based on the distance between the external implant collar and the bony surface on the buccal plate (I-BP). A secondary aim is to assess the esthetic outcome via the implant esthetic score (IAS). METHODS: This prospective cohort study was performed in three centers. Suitable patients to undergo implant placement in fresh extraction sockets were selected. Periodontal biotype, horizontal and vertical peri-implant bone defects, and dehiscences were assessed. Depending on I-BP, two types of grafting procedures were performed. In group A (I-BP <4 mm), only the peri-implant gap was grafted during the surgical phase (internal grafting [IG]), whereas group B (I-BP ≥ 4 mm) received both internal and external grafting (IEG). Master casts of the sites, made before implant placement and after 1 year of loading, were optically scanned. A computerized analysis of the contour changes at the involved sites was performed by superimposing the scanned models. RESULTS: A total of 20 patients (eight males and 12 females) were recruited, and 20 non-submerged implants were placed in fresh extraction sockets. No implant failed during the observation period. The mean follow-up was 25 months (range: 12 to 37 months). After 1 year of loading, group A showed a slight decrease in mean buccal volume, whereas group B had an increase in volume (P = 0.02). IAS was higher for group B than group A. CONCLUSIONS: When implants are placed immediately after tooth extraction, I-BP may represent a useful diagnostic parameter in choosing the most appropriate grafting procedure (IG versus IEG). In clinical cases in which the distance between implant surface and the buccal plate is <4 mm, the combination of internal and external grafting (IEG) is recommended to maintain the volume and the contour of the ridge and achieve a successful esthetic outcome.

Sinus lift tissue engineering using autologous pulp micro-grafts: A case report of bone density evaluation.

BACKGROUND: Although autografts are the standard procedure for bone grafting, the use of bone regeneration by means of dental pulp stem cell is an alternative that opens a new era in this field. Rigenera Protocol is a new technique able to provide the surgeon autologous pulp micro-grafts. MATERIALS AND METHODS: At the Department of Oral Surgery, Don Orione Hospital, Bergamo, Italy, one patient underwent sinus lift elevation with pulp stem micro-grafts gentle poured onto collagen sponge. A CT scan control was performed after 4 months and DICOM data were processed with medical imaging software which gives the possibility to use a virtual probe to extract the bone density. Pearson's Chi-square test was used to investigate difference in bone density (BD) between native and newly formed bone. RESULTS: BD in newly formed bone is about the double of native bone. CONCLUSION: This report demonstrated that micro-grafts derived from dental pulp poured onto collagen sponge are a useful method for bone regeneration in atrophic maxilla.

Fence technique: guided bone regeneration for extensive three-dimensional augmentation.

This report describes a novel bone reconstructive technique based on guided bone regeneration for extensive three-dimensional hard tissue augmentation. This two-stage technique utilizes bioresorbable osteosynthesis plates, pins, and collagen membranes that form a physical barrier resembling a fence, which contains the bone graft biomaterials composed of a combination of deproteinized bovine bone matrix and autologous bone grafted from intraoral sites. This technique can result in significant bone regeneration with minimal patient discomfort. Four case reports are presented. Histologic analysis of specimens shows the presence of mature bone. This procedure yields favorable results for bone formation, implant placement, and patient satisfaction.

Short communication: use of a diagnostic software to predict bone density and implant stability in preoperative CTs.

BACKGROUND: Computerized tomographs (CTs) are commonly used for presurgical planning of dental implant placement. It is possible that implant stability can be predicted based on quantitative measurements of bone density at planned implants sites with the use of diagnostic software. PURPOSE: The aim was to evaluate if there is a correlation between bone density measurements in specific implant positions in preoperative CTs and insertion torque (IT) and implant stability measurements when placing the implants. MATERIALS AND METHODS: The study comprised of four patients in whom presurgical CTs had been used to plan implant treatment. A total of 26 implants (Neoss, Harrogate, UK) were placed in the totally edentulous maxilla (n=3) or mandible (n=1). IT was measured during implant insertion and the torque/time curves examined for mean IT (newton-centimeters) over the total curve. The stability of implants was measured with resonance frequency analysis. The positions of the implants were extracted from a postoperative CT to the preoperative one. Bone density was measured with a dedicated software (3Diagnosys™ 3.0, 3Diemme, Cantù, Italy) in virtual hollow probes, indicating the bone volume within 1mm from each implant surface. The Spearman Rank correlation test was used to find possible correlations. RESULTS: Statistically significant correlations were found between mean bone density, mean IT, and implant stability measurements. CONCLUSIONS: This pilot study showed a correlation between bone density, as measured in Hounsfield units in preoperative CTs, and IT and implant stability measurements at the surgical placement of the implants. The findings support the idea that integration of bone density measurements in implant probes in preoperative CTs using treatment-planning software may be a useful feature to predict implant stability and to avoid failures.

Reliability of voxel gray values in cone beam computed tomography for preoperative implant planning assessment.

PURPOSE: To assess the reliability of cone beam computed tomography (CBCT) voxel gray value measurements using Hounsfield units (HU) derived from multislice computed tomography (MSCT) as a clinical reference (gold standard). MATERIALS AND METHODS: Ten partially edentulous human mandibular cadavers were scanned by two types of computed tomography (CT) modalities: multislice CT and cone beam CT. On MSCT scans, eight regions of interest (ROI) designating the site for preoperative implant placement were selected in each mandible. The datasets from both CT systems were matched using a three-dimensional (3D) registration algorithm. The mean voxel gray values of the region around the implant sites were compared between MSCT and CBCT. RESULTS: Significant differences between the mean gray values obtained by CBCT and HU by MSCT were found. In all the selected ROIs, CBCT showed higher mean values than MSCT. A strong correlation (R=0.968) between mean voxel gray values of CBCT and mean HU of MSCT was determined. CONCLUSIONS: Voxel gray values from CBCT deviate from actual HU units. However, a strong linear correlation exists, which may permit deriving actual HU units from CBCT using linear regression models.