Dr Andre van Zyl Published Research 

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

Authors: Beetge MM1 , Todorovic VS1,2,2, Oettlé A3, Hoffman J4 , van Zyl AW1

Author information:
1 Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria.
2 School of Dental Medicine, University of Belgrade.
3 Department of Anatomy, Faculty of Health Sciences, University of Pretoria.
4 South African Nuclear Energy Corporation.

Abstract

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.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za


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

Authors: Schnetler C, Todorovic VS1, van Zyl AW2

Author information:
1 ITI Scholar, Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria, Pretoria, South Africa.
2 Professor, Head of Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria, Hatfield, South Africa.

Abstract:

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.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za


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

Authors: Todorovic VS1,2, Vasovic M3, Beetge MM2, van Zyl AW2, Kokovic V4
Author information

1   Oral Surgery Department, School of Dental Medicine, University of Belgrade, Serbia.
2  Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria, South Africa.
3   Department of Dentistry, Faculty of Medical Sciences, University of Kragujevac, Serbia.
4   Advanced Europe Medical Centre, Dental Department, Sharjah, United Arab Emirates.

Abstract:

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.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za


The midline mandibular lingual canal: importance in implant surgery

Authors: Oettlé AC1, Fourie J, Human-Baron R, van Zyl AW

Author information

1 Department of Anatomy, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.

Abstract:

PurposeThe study aims to determine if midline mandibular dental implants pose a risk for the midline lingual canal (MLC).Materials and Methods Cone beam computed tomography was used to scan 122 mandibles (31 black males; 28 black females; 32 white males and 31 white females). Midsagittal sections in the reconstructed images were made. A measurement of 6 mm across bucco-lingually was delineated as the minimum dimensions for implant placement. In dentate cases with a bucco-lingual distance in excess of 6 mm, the measurement was across the apex of the socket to determine the bone dimension available below the socket for implant placement. From these markers a vertical line was dropped to the MLC to measure the available bone.ResultsThe MLC was a consistent finding. A statistical significant difference in bone availability among the sexes and dentition pattern was found, indicating that midline implants in edentulous females posed a risk of injury to the vessels of the MLC.Conclusion Implants in the position of lower central incisors are regarded as a safe procedure. Clinicians should however take note of the position of the midline mandibular lingual canal and approach this area with caution, especially if the alveolar ridge is to be reduced before implant placement.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za


Correlation between dysplasia and ploidy status in oral leukoplakia

Authors: van Zyl AW1, van Heerden MB, Langenegger E, van Heerden WF

Author information

1 Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria, Pretoria, South Africa

Abstract:

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.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za


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

Authors: van Zyl AW1, van Heerden WF

Author information

1 Department of Periodontics and Oral Medicine, School of Dentistry, University of Pretoria, Pretoria, South Africa. andrevanzyl@up.ac.za

Abstract:

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. 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. 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). 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.

For more information on Dr Andre van Zyl Published Research, email: andre@andrevanzyl.co.za

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