Computer-Aided Design Evaluation of Harvestable Mandibular Bone Volume: A Clinical and Tomographic Human Study

Autologous bone harvested during implant bed preparation: A randomized clinical trial comparing high-speed drilling with irrigation versus low-speed drilling without irrigation

OBJECTIVE

To compare collected bone weight and the frequency of autologous bone harvesting from the flutes of surgical drills used for implant bed preparation using two different drilling techniques. A comparative evaluation of radiographic bone density and bone quality was also made.

MATERIALS AND METHODS

A randomized clinical trial was made of 66 dental implants in patients with a single posterior edentulous site. The compared drilling techniques were high-speed drilling with irrigation (control group) and low-speed drilling without irrigation (test group). The bone collected in both groups was dried and weighed with a precise electronic balance. The frequency of harvesting was calculated. The median radiographic bone density of each implant site was measured using cone-beam computed tomography (CBCT) pixel values. Patient sex, age, implant position and dimensions, as well as the last drill diameter were analyzed as independent variables. The level of significance was 5%.

RESULTS

The harvesting of bone chips from drill flutes proved possible in 51.5% of the procedures in the control group and in 100% in the test group (p < 0.001). There were also statistically significant differences in bone weight between the control group (6.7 ± 10.6 mg) and the test group (41.9 ± 30.3 mg) (p < 0.001). The CBCT pixel values were directly correlated with the collected bone weight in both groups. The median radiographic bone density, arch and last drill diameter were significantly associated with harvesting bone frequency and collected bone weight (p < 0.05).

CONCLUSIONS

Our findings suggest that the frequency and weight of autologous bone harvested from drills are greater with low-speed drilling without irrigation than with high-speed drilling with irrigation. Radiographic bone density, arch and last drill diameter also significantly influenced the harvesting outcomes.

Three-dimensional radiographic assessment of the mandibular retromolar donor site in different vertical facial growth types

PURPOSE

To assess volumetrically, the impact of vertical facial growth types (VGFT) on the retromolar area as a bone donor site MATERIAL AND METHODS: 60 cone beam computed tomography (CBCT) scans of adult individuals were classified in three groups according to their SN-GoGn angle: hypodivergent group (hG) (33.33%), normodivergent group (NG) (30%) and hyperdivergent group (HG) (36.67%). Total harvestable bone volume and surface (TBV and TBS respectively), total cortical and cancellous bone volume (TCBV and TcBV respectively) and the percentage of cortical and cancellous bone volume (CBV and cBV respectively) were evaluated.

RESULTS

The whole sample showed a mean TBV of 1220.99±448.81mm³ and a mean TBS of 940.29±259.93mm². Statistically significant differences were found between the different outcome variables and the vertical growth patterns (p<0.001). TBS differs for the different vertical growth patterns with the highest mean of TBS observed in the hG group. TBV also significantly differs between the different vertical growth patterns (p<0.001) with the highest mean observed for the hG individuals. Significant differences in percentages of cBV and CBV were present between the hyper-divergent groups and the other groups (p<0.001) with the hyper-divergent group having the lowest percentage of CBV and the highest percentage of cBV.

CONCLUSION

hypodivergent individuals tend to have thicker bone blocks that can be used in onlay technique while thinner bone blocks harvested from hyperdivergent and normodivergent individuals can be used in three-dimensional grafting approach.

Determination of the Volume and Density of Mandibular Ramus as a Donor Site Using CBCT

Introduction

This study aimed to assess the quantity and quality of available bone to provide the autologous bone graft from mandibular ramus.

Material and Methods

CBCT scans were collected and mandibular ramus was evaluated by measuring a variety of parameters including volume, bone height, cortical, and cancellous bone thickness. Data analysis was performed using descriptive statistics and inferential statistics. We used the Kolmogorov-Smirnov test for the evaluation of data normality. We then applied Pearson correlation and independent t-test for normal variables, and Spearman and Mann-Whitney correlation tests for abnormal variables. Statistical analysis was performed using SPSS version 19 and P value < 0.05 was considered significant.

Results

A total of 52 women and 32 men (aged 21 to 70) were included in this study. The mean bone volume was 2.7 ± 0.70 cm3 [95%confidence interval (CI) 1.3-4.5]. The mean bone density in the middle section was 1016.36 ± 231.58 Gy value (95% CI 475.6-1520.9). Kolmogorov-Smirnov test revealed that the variables such as apical cortical/cancellous ratio (P = 0.005), middle-cancellous bone thickness (P = 0.016), and middle cortical/cancellous ratio (P = 0.005) were abnormal and the rest were normal. Bone density, as well as the amount of cortical bone in the middle and apical regions, had a significant reverse correlation with age (P < 0.001).

Conclusion

The volume, density, and cortical/cancellous ratio are independent of sex. The reverse relationship between age and bone density, as well as the amount of cortical bone in several parts, indicates a decrease in bone quality with aging.

Fully digital versus conventional workflow for horizontal ridge augmentation with intraoral block bone: A randomized controlled clinical trial

OBJECTIVES

To compare the outcome and efficiency of the computer-aided intraoral block bone grafting procedure with those of the conventional technique for the augmentation of horizontal ridge defects.

MATERIALS AND METHODS

A total of 28 patients with single missing tooth in esthetic zone with class IV horizontal alveolar bone defect in need of dental implant restoration were recruited. Computer-aided design of the implant restoration and intraoral block bone grafting was performed for all the participants. The patients were randomly and equally divided into guide and control groups. A fully guided bone harvesting, trimming, and grafting surgery was executed in the guide group. The control group patients underwent surgery without any guide. After 6 months, all the patients underwent implant placement. The primary outcomes were the root mean square estimate (RMSE) values between the outer contours of the actual implanted and planned bone block as well as the RMSE values between the inner surface of the implanted bone block and the original bone surface of the recipient site immediately after surgery. The secondary outcomes were the trimming time of bone block and the surgery-associated complications. The postoperative visual analog scale (VAS) of pain, swelling, and mouth opening difficulty was recorded.

RESULTS

All 28 patients underwent intraoral block bone grafting, followed by the placement of implant after 191.8 ± 19.69 days. The RMSE values between the outer contours of the implanted and planned bone blocks were significantly lower in the guide group (0.37 ± 0.16 mm) as compared to those in the control group (0.72 ± 0.29 mm) (p = 0.0007). The RMSE values between the inner contours of the graft block and original bone at the recipient site were lower in the guide group (0.35 ± 0.15 mm) as compared to those in the control group (0.48 ± 0.17 mm) (p = 0.043). The duration of bone block trimming was shorter in the guide group (401.51 ± 97.60 s) as compared to the control group (602.36 ± 160.57 s) (p = 0.0005). In the control group, two patients received secondary bone grafting, one patient experienced bleeding of donor site and temporary hypoesthesia of the lower lip and chin skin, and one patient developed temporary sensitivity of the adjacent tooth.

CONCLUSIONS

As compared to the conventional procedure, the fully digital workflow in the present study seemed to be a more accuracy and effective protocol for horizontal ridge augmentation with intraoral block bone.

TRIAL REGISTRATION

Chictr.org.cn (ChiCTR2000036390).

CBCT Evaluation of the maxillary palatine process as a donor site for the regeneration of periodontal defects

Background

The maxillary palatine process (MPP) is an excellent source of autogenous bone transplants for anterior maxillary reconstruction. This research aimed to determine the quantity and quality of accessible MPP as a donor location.

Methods

Cone-beam computed tomography (CBCT) scans of patients referred to the School of Dentistry were evaluated by a certified examiner. The harvestable MPP was defined as the space between the distal surfaces of maxillary first premolars. OnDemand 3D Imaging software was used to determine bone properties. SPSS software was used to investigate the following variables: Bone characteristics are correlated with age and gender, accessible volume, and palatal width and height. P<0.05 was defined as the level of statistical significance.

Results

This study was performed on CBCT scans of 81 subjects (41 females and 40 males). MPP volume and palatal heights were 1.33±0.53 cm3 and 20.86±5.51 mm, respectively. Maximum bone density was observed around lateral incisors. Palatal width was 33.81±2.42 mm between canines and 41.81±2.66 mm between premolars. The MPP volume was significantly greater in males (P<0.001). Additionally, there was a positive correlation between the volume and palatal width (P<0.05).

Conclusion

Within the constraints of this research, there is a limited supply of MMP accessible for use as a graft source, and it is best suited for treating localized bone lesions. The favorable link between palatal breadth and harvestable volume aids the surgeon in estimating the quantity of bone accessible during the first evaluation.

Anatomical Variations of the Mandibular Symphysis in a Normal Occlusion Population Using Cone-Beam Computed Tomography

This study aimed to assess the anatomical variations of the mandibular symphysis in a normal occlusion population using cone-beam computed tomography (CBCT). This retrospective cross-sectional study evaluated 200 CBCT scans of patients aged ≥17 with class I occlusion, 1-3 mm overbite and overjet, and <3 mm crowding. The CBCT scans were obtained with NewTom 3G scanner with the exposure settings of 110 kVp, 1.2 mA, 5.4 s time, and six-inch field of view and saved in NNT Viewer. The anterior loop length, labial bone thickness, mandibular bone height at the symphysis, and cortical bone thickness at the right and left canine teeth and central and lateral incisors were measured and compared between males and females and different age groups using one-way ANOVA. The intra- and inter-observer agreements for all landmarks were ICC >0.9 (excellent). The mean length of the anterior loop in females was significantly greater than that in males (P=0.02). Different age groups had significant differences in cortical bone width at the site of the left canine (P=0.03) and vertical bone height at the site of the right central incisor (P=0.05). The majority of parameters related to the mandibular symphysis were greater in normal occlusion males than females. Preoperative CBCT assessment of the mandibular symphysis can greatly help in diagnosis and treatment planning as well as bone harvesting from this area.

Long-term stable vertical bone regeneration after sinus floor elevation and simultaneous implant placement with and without grafting

BACKGROUND

Less invasive surgical approaches to regenerate bone intra-sinus and allow long-term functional implant stability are needed.

PURPOSE

To evaluate long-term vertical bone regeneration after sinus floor elevation and simultaneous implant placement with and without bone grafting.

METHODS

Vertical bone gains (VBG) post-sinus elevation, with and without grafting, were evaluated in thirty individuals presenting an average residual bone height (RBH) of 4.2 mm using a standardized digital technique. Measurements were taken preoperatively, and at an average of 64.6 months follow-up. Clinically, peri-implant tissues were assessed for pocket formation and presence of inflammation to evaluate established success criteria.

RESULTS

Overall, RBH averaged 4.2 ± 1.1 mm (range: 1.8-5.8) and VBG 7.7 ± 1.6 mm (range: 6.0-12.9). Mean difference of 7.6 mm between vertical bone heights (VBH) at augmented implants sites and initial RBH, 11.8 versus 4.2 mm, (P < .0001, CI95%: 6.9-8.2) was statistically significant. RBH averaged 4.5 ± 0.8 mm and 3.8 ± 1.2 (P = .07) and VBG 6.8 ± 0.5 and 8.5 ± 1.9 mm (P = .003, CI95%: 0.6-2.7), for nongrafted and grafted individuals, respectively. The grafting group received an average graft volume of 0.35 ± 0.1 cc (range: 0.25-0.5) per implant site. Long-term follow-ups average 64.6 months (range: 36-144) and all implants met the success criteria. VBG ≥ 7 mm were 7.3 times more likely to develop on grafted sites (OR = 7.3, P = 0.02, CI95%: 1.2-46.2).

CONCLUSION

None to negligible amounts of grafting material are required to regenerate substantial amounts of autogenous bone into atrophic sinus cavities after simultaneous implant placement. The regenerated VBH seems stable for functional implant stability long-term. Implant success rates were 100% at an average of 64.6 months.

Volumetric Evaluation of Safe Zone for Bone Harvesting From Symphysis Region by Using Cone Beam Computed Tomography

OBJECTIVES

The aim of the present study was to retrospectively make a volumetric evaluation of symphysis sites of patients by the use of cone beam computed tomography (CBCT).

METHODS

This retrospective study evaluated dentate symphysis region of the mandibles in CBCT scans taken for different reasons in 90 patients (45 women and 45 men). Three-dimensional (3D) data were obtained using a CBCT device Kodak 9000 3D CMOS sensor with optical fiber. CBCT images were then transferred as digital imaging and communications in medicine files and imported into a volumetric-rendering software 3D DOCTOR (Able Software Corp., Lexington, MA) capable of measurements of vector based-segmentation technology for volumetric measurements.

RESULTS

The total average bone volume is 2616.45 mm. Significant differences in average bone volume were found between group I and group IV (P < 0.001). Higher bone volume was obtained in the male groups (2903.01 mm) than in the female groups (2329.88 mm).

CONCLUSIONS

CBCT is a good candidate for 3D assessment of high-contrast structures in the oral region. We suggest that the use of 3D computed tomography in combination with a software program is a dependable means of measuring the volume of the symphysis bone graft.

Quantitation of Mandibular Symphysis Bone as Source of Bone Grafting: Description in Class I and Class III Skeletal Conditions

The aim of this study was to quantify the cortical and cancellous bone in the mandibular symphysis and relate it to the teeth and to the skeletal class. A descriptive study was conducted using cone beam computerized tomography (CBCT). Class I and class III subjects were included, defined according to dental occlusion and cephalogram results. Linear measurements were taken on the CBCT of the mandibular canines, lateral incisors, and central incisors, where the analysis was related to the axial and apical axes considering the bone in relation to the dental area. With previous definitions, an observer took 2 measurements of the height of the mandibular symphysis, cortical bone of the buccal and lower region, and thickness of cancellous bone at different levels; the correlation coefficient between the first and second measurement was 0.99 and presented P = .001. The results were analyzed with analysis of variance and Tukey's honest significant difference test, with P < .05 being statistically significant. The symphysis height was significantly greater in class III subjects. The cortical bone was an average 1.67 ± 0.44 mm in vertical distance in the skeletal class I group and 1.74 ± 0.47 mm in the class III group. The cancellous bone had an average width of 5.03 ± 1.94 mm in the skeletal class I group and 4.74 ± 2.05 mm in the class III group. It was observed that cancellous bone was significantly thicker at the incisor level than at the canine level. There were anatomical differences between skeletal class I and class III subjects, although the clinical significance may be questionable. With the values from these analyses, it may be concluded that there are no significant differences in quantitation of the cortical and cancellous bone in the anterior mandibular symphysis.

Autogenous bone block grafting provides facial implant tissue stability long-term

BACKGROUND

Mucosal recession (MR) and bone loss can compromise anterior implant esthetics.

PURPOSE

To evaluate tissue stability and clinical outcomes of anterior implants augmented with autogenous block transplants long-term.

MATERIALS AND METHODS

This prospective cross-sectional clinical study analyzed facial tissue recession of anterior implants augmented with autogenous bone blocks and compared them to adjacent teeth in forty patients 52 months post-augmentation. Clinical parameters, MR and implant transparency, were assessed at delivery and follow-up. The hypothesis is that the facial mucosa of augmented implant sites is more resistant to trauma than the gingival margins of adjacent teeth.

RESULTS

Teeth were seven times more likely to present a facial recession than adjacent augmented implants at 52-month follow-up (RR: 7; P < .001; 95%CI: 2.7-18.0). Augmented implant sites were six times more likely to present "no-tissue-recession" than adjacent teeth (RR: 6.2; P < .001; 95%CI: 2.4-15.7). Mean tooth facial tissue recession was significantly higher than adjacent implants, 1.18 ± 1.05 mm (range: 0-3.5 mm) vs. 0.06 ± 0.2 mm (95%CI: 0.8-1.5; P < .0001). Thick biotype teeth were 2 times more resistant to recession than thin biotype teeth (RR: 2.03; P = .03; 95%CI: 1.2-3.5). Implant success rates were 100%. Lack of transparency and MR at facial implant sites lasted an average of 52 months and up to 144 without signs of inflammation or pocket formation regardless of the individual's biotype. Facial bone thicknesses of 2.2 mm seem optimal for tissue stability.

CONCLUSIONS

Autogenous bone block augmentation with staged implant placement seems to be a predictable, short-healing, reconstructive protocol in the esthetic zone maintaining stable peri-implant tissues long-term. Implant augmented sites seem more resistant to develop a recession than adjacent teeth.

Radiographic evaluation of the symphysis menti as a donor site for an autologous bone graft in pre-implant surgery

Purpose

This study was performed to obtain a quantitative evaluation of the cortical and cancellous bone graft harvestable from the mental and canine regions, and to evaluate the cortical vestibular thickness.

Materials and Methods

This study collected cone-beam computed tomographic (CBCT) images of 100 Italian patients. The limits of the mental region were established: 5 mm in front of the medial margin of each mental foramen, 5 mm under the apex of each tooth present, and above the inferior mandibular cortex. Cortical and cancellous bone volumes were evaluated using SimPlant software (SimPlant 3-D Pro, Materialize, Leuven, Belgium) tools. In addition, the cortical vestibular thickness (minimal and maximal values) was evaluated in 3 cross-sections corresponding to the right canine tooth (3_R), the median section (M), and the left canine tooth (3_L).

Results

The cortical volume was 0.71±0.23 mL (0.27-1.96 mL) and the cancellous volume was 2.16±0.76 mL (0.86-6.28 mL). The minimal cortical vestibular thickness was 1.54±0.41 mm (0.61-3.25 mm), and the maximal cortical vestibular thickness was 3.14±0.75mm(1.01-5.83 mm).

Conclusion

The use of the imaging software allowed a patient-specific assessment of mental and canine region bone availability. The proposed evaluation method might help the surgeon in the selection of the donor site by the comparison between bone availability in the donor site and the reconstructive exigency of the recipient site.