Buccal and palatal alveolar bone dimensions in the anterior maxilla: A micro-CT study.

OBJECTIVE: Anterior maxillary immediate implant placement has become a popular procedure. It has aesthetic and functional risks. A prerequisite for success is sufficient alveolar bone for primary stability. Many cone-beam computed tomography (CBCT) studies have assessed alveolar bone dimensions in the anterior maxilla, with varying results. More accurate information on the alveolar bone dimensions in the anterior maxilla is required. The objective of the present study was to evaluate bone dimensions in the anterior maxilla using micro-CT, a high-resolution imaging tool. MATERIALS AND METHODS: Seventy-two human skulls were scanned using micro-CT at the South African Nuclear Energy Corporation. Specialized software was used for 3-D rendering, segmentation, and visualization of the reconstructed volume data. Axial planes were created over each alveolus/tooth from canine to canine. Buccal and palatal bone dimensions were measured at crestal, 3 mm, 6 mm, and 9 mm levels. RESULTS: Buccal bone rarely exceeded 0.5 mm, consisting of bundle bone only for all investigated teeth at all levels. Up to a third of teeth showed buccal fenestrations. Alveolar bone on the palatal side was thicker than buccal and increased from <1 mm at crestal level up to 3.77 mm, 4.56 mm, and 5.43 mm for centrals, laterals, and canines at the 9 mm level, respectively. CONCLUSIONS: Immediate implants in the anterior maxillae has anatomical risks. Alveolar bone on the buccal aspect is very thin, with fenestrations in certain positions. Therefore, a thorough planning and individual approach are needed to avoid possible complications and achieve stable aesthetic and functional results in the long-term.

A micro-CT study of the greater palatine foramen in human skulls.

The greater palatine foramen (GPF) is an important anatomical landmark and has substantial clinical relevance in dental surgery. Knowledge of its precise location and dimensions is required for proper planning of surgical procedures involving the posterior maxilla. We used microfocus computed tomography to determine the location and dimensions of the GPF, and any sex and race variations in those measurements, in 77 human skulls scanned at the South African Nuclear Energy Corporation. Specialized software was used for three-dimensional rendering, segmentation, and visualization of the reconstructed volume data. GPF location ranged from adjacent to the first molar to distal of the third molar. The most common GPF location was near the third molar (66.7% of skulls), and the GPF was as close as 6.31 mm (mean distance 12.75 ± 3 mm). The mean GPF dimensions were 5.22 mm on the anterior-posterior axis and 2.81 mm on the lateral-medial axis. We noted no significant differences in relation to race, sex, or age in the sample. The GPF was adjacent or posterior to the third maxillary molar in most skulls.

Anterior Mandibular Lingual Defect As a Possible Cause of Near-Fatal Bleeding During Routine Dental Implant Surgery: A Retrospective Computed Tomography Study.

INTRODUCTION: The anterior mandible is generally regarded as a safe anatomical region for implant placement. However, anatomical variations may lead to severe intraoperative complications with potential fatal outcome. The objective of this study was to evaluate the anterior mandibular lingual defect (AMLD) in patients undergoing implant surgery. MATERIALS AND METHODS: The CT data of 338 consecutive dental implant patients were reformatted with appropriate software. The AMLDs were first identified using 3-D reconstruction and further evaluated in the relevant 2-D slices. RESULTS: The AMLD was present in 10.95% of patients; of these, 83.8% were present bilaterally. No significant differences were found between sex, age, or race within the investigated population with regards to the presence of the AMLD. CONCLUSIONS: The presence of an AMLD might be a possible cause of near-fatal bleeding during routine dental implant surgery. This study found the presence of the AMLD in a small (10.95%), but not negligible number of patients. To avoid possible complications, meticulous planning and the use of 3-D imaging are advisable before performing implant surgery in this anatomical region.

Stability Development of Immediately Loaded Hybrid Self-Tapping Implants Inserted in the Posterior Maxilla: 1-Year Results of a Randomized Controlled Trial.

The objective of the present study was to elucidate stability development of immediately loaded hybrid self-tapping implants inserted in the posterior maxilla. Forty-eight hybrid self-tapping implants with a chemically modified surface (∅4.1; length: 8 mm) were inserted bilaterally in the maxillary first and second premolar and first molar sites of 8 patients. In each patient, both sides of the maxilla were assigned randomly to either immediate (IL) or early (EL) loading group. Implant stability was evaluated by means of resonance frequency analysis immediately after implant placement and after 1, 2, 3, 4, 5, 6, 12, 26, and 52 weeks. High values of primary stability were found in both groups (71.91 ± 6.52 implant stability quotient [ISQ] in IL group; 73.87 ± 6.5 ISQ in EL group), with significant differences between the groups at the different time points. Initial decrease in stability was observed between the first and fifth weeks in the IL group and between the first and third weeks for the EL group. In the IL group 1 implant was removed after 3 weeks due to lack of stability. Early results of this study showed the ability of hybrid self-tapping dental implants with a chemically modified surface to achieve sufficient primary stability and to maintain high values of secondary implant stability in bone type 3 and 4, even when loaded immediately. Minimal alterations in stability were observed for both investigated groups, but the EL group showed faster recovery after an initial drop in stability.

Correlation between dysplasia and ploidy status in oral leukoplakia.

Oral leukoplakia and other potentially malignant disorders (PMD) may progress to oral squamous cell carcinoma (OSCC). The gold standard for assessing the potential for malignant transformation remains histologic examination with the aim of grading the dysplastic changes. However, not all lesions with dysplasia will progress to OSCC. DNA ploidy has been suggested as a method to predict the clinical behaviour of PMD. This study reports on the use of high-resolution flow cytometry to determine the ploidy status of formalin-fixed, paraffin-embedded material from PMD compared to their dysplasia grade on histology. Aneuploidy was found in 13 % of mild, 31 % of moderate, and 54 % of severe dysplasia cases. This difference was statistically significant (p = 0.011). The differences in ploidy status were more significant when grouping the dysplasia into low-risk and high-risk categories (p = 0.008). These findings indicate that the ploidy status of PMD as determined by high-resolution flow cytometry may be of value in predicting biological behaviour in PMD such as leukoplakia.

A retrospective analysis of maxillary sinus septa on reformatted computerised tomography scans.

OBJECTIVES: This study analysed 200 consecutive computerised tomography (CT) scans, reformatted with specialised software for the identification of maxillary sinus septa. All patients were routine implant patients who had undergone CT scans for dental implant planning. MATERIALS AND METHODS: The data of two hundred consecutive patients (400 maxillary sinuses) who had been sent for CT scan, were reformatted with CT software. The group consisted of 115 edentulous and 85 dentate (below sinuses) patients. Septa were identified using three-dimensional (3D) reconstruction and panoramic views. No septa were included unless they were clearly visible on the 3D reconstruction. The prevalence, height and number of septa were analysed for both groups of patients. RESULTS: The prevalence of sinus septa was found to be 69% (138 patients), with a significant number of these patients showing multiple septa (89/138). The mean age of the patients was 54 (+/-14). The prevalence of edentulous patients with septa (71%) was not statistically different from the dentate patients (66%) (P=0.7). DISCUSSION: This study found a higher prevalence of patients with maxillary sinus septa than what has been reported previously. This may be due to the exact nature of the CT software and the ease of use of the 3D reconstruction for identification of septa. Another explanation could be that all septa that were visible on the 3D reconstruction were included and there was no minimum cut-off height. No significant differences were found between edentulous and dentate patients.