Somayeh H. Ahmad, DDS, Dr. Med. Dent.

All Publications

• Dental Composite Offers Comparable or Greater Pullout and Shear Strength to Lateral Mass Screw Fixation in a Human Cadaveric Model. International journal of spine surgery Wadhwa, H., Castro, J., Okoli, O., Chan, C., Ahmad, S. H., Karnowska, A., Hu, S. S., Koltsov, J. C., Bruckman, K. C., Mok, J. M. 2026

  Abstract

  Lateral mass screw fixation is the common method of fixation for an instrumented posterior fusion of the subaxial cervical spine. While screws have established efficacy, adhesive material that can be applied to the bony surface may be a promising alternative strategy owing to ease of application, size, and avoidance of screw loosening, malposition, or fracture.Eighteen fresh frozen human cadaveric subaxial cervical vertebrae were prepared for biomechanical testing. In each vertebra, 1 side underwent lateral mass screw fixation, and the contralateral side underwent composite fixation. On the screw side, a 12 × 3.5-mm lateral mass screw was inserted using a standard free-hand technique by a spine surgeon. For the dental composite side, the lamina was treated with etching acid solution and a dental bonding agent over a 10-mm diameter area before an orthodontic metal bracket was attached using dental composite. Nine specimens in each group were subjected to an axial load to failure (pullout) test, where the load was perpendicular to the vertebral surface. The remaining specimens were subjected to cyclical testing, where the load was applied cranially (shear) relative to each vertebra and gradually increased with each cycle until failure occurred. Differences were assessed with paired t tests with a 2-sided level of significance of α = 0.05.Under axial load (pullout), the dental composite (203.4 ± 43.4 N) showed higher ultimate load than the screws (127.7 ± 21.2 N; P < 0.001). The predominant failure mode under axial load was the composite pulling off the cortical bone surface, whereas the screw pulled through the cancellous and cortical bone. In cyclical testing, the ultimate shear load of dental composite (163.7 ± 48.4 N) did not differ from lateral mass screws (173.6 ± 65.5 N; P = 0.7). The composite failure mechanism under shear loading for half of the specimens was composite separation from bone, whereas the rest failed due to fractures distant from the composite site, indicating robust fixation integrity of composite to bone.Dental composite displayed similar shear strength and greater pullout strength compared with lateral mass screws.An adhesion-based fixation strategy may serve as a viable alternative to traditional screws in specific clinical scenarios that are worthy of further investigation.

  View details for DOI 10.14444/8871

  View details for PubMedID 41932832

• Dental Cement Augmentation Increases Pullout Strength with Comparable Removal Torque for Lateral Mass Screws. Spine Castro, J., Wadhwa, H., Okoli, O., Chan, C., Ahmad, S. H., Karnowska, A., Hu, S., Koltsov, J., Bruckman, K., Mok, J. 2025

  Abstract

  Biomechanical/basic science.To evaluate efficacy of dental cement augmentation of lateral mass screws in the cervical spine.Premature loosening and fixation failure is a known problem of screw fixation of the spine, especially in cases of poor bone quality. Cement augmentation of screws with PMMA has limited utility in the cervical spine due to the small size of the bone and high risk of extravasation. Augmentation with dental cement may present a viable solution for posterior cervical spinal screw fixation.15 cadaveric cervical vertebra were prepared. Lateral mass screw fixation (3.5×12 mm) was performed bilaterally with standard freehand technique by an attending spine surgeon. For augmented screws, dental composite was applied into the screw hole before placement of the screw. 9 vertebrae were used for pull-out testing. Screws were attached to a material testing machine and axially loaded until failure. In the remaining 6 vertebrae, peak torque required to remove the screws from bone was measured via a digital torque driver. A t-test was used to analyze the results between the augmented and non-augmented groups with significance set to P<0.05.Augmented lateral mass screws exhibited significantly higher pullout strength (263.8±79.4N) compared to non-augmented screws (127.7±21.2N). (P=0.0005) There was no significant difference in the mean torque required for screw removal between the augmented (4.20±2.83 lb-in) and non-augmented groups (4.49±2.09 lb-in) (P=0.9). The dental composite was radio-opaque and observable on xray.Augmentation with dental composite enhanced pullout strength without altering removal torque of cervical lateral mass screws in human bone. Dental cement augmentation of lateral mass screws during subaxial cervical spine fusion may be a safe and effective method of improving fixation strength without affecting ease of revision.

  View details for DOI 10.1097/BRS.0000000000005461

  View details for PubMedID 40705348

• Towards multiomic analysis of oral mucosal pathologies. Seminars in immunopathology Einhaus, J., Han, X., Feyaerts, D., Sunwoo, J., Gaudilliere, B., Ahmad, S. H., Aghaeepour, N., Bruckman, K., Ojcius, D., Schurch, C. M., Gaudilliere, D. K. 2023

  Abstract

  Oral mucosal pathologies comprise an array of diseases with worldwide prevalence and medical relevance. Affecting a confined space with crucial physiological and social functions, oral pathologies can be mutilating and drastically reduce quality of life. Despite their relevance, treatment for these diseases is often far from curative and remains vastly understudied. While multiple factors are involved in the pathogenesis of oral mucosal pathologies, the host's immune system plays a major role in the development, maintenance, and resolution of these diseases. Consequently, a precise understanding of immunological mechanisms implicated in oral mucosal pathologies is critical (1) to identify accurate, mechanistic biomarkers of clinical outcomes; (2) to develop targeted immunotherapeutic strategies; and (3) to individualize prevention and treatment approaches. Here, we review key elements of the immune system's role in oral mucosal pathologies that hold promise to overcome limitations in current diagnostic and therapeutic approaches. We emphasize recent and ongoing multiomic and single-cell approaches that enable an integrative view of these pathophysiological processes and thereby provide unifying and clinically relevant biological signatures.

  View details for DOI 10.1007/s00281-022-00982-0

  View details for PubMedID 36790488

• Prevalence of Molar-Incisor Hypomineralisation in an Emerging Community, and a Possible Correlation with Caries, Fluorosis and Socioeconomic Status. Oral health & preventive dentistry Ahmad, S. H., Petrou, M. A., Alhumrani, A., Hashim, R., Splieth, C. 2019; 17 (4): 323-327

  Abstract

  To determine the prevalence of molar-incisor hypomineralisation (MIH) in 7- to 9-year-old (±1 year) schoolchildren living in Dubai, United Arab Emirates, and to find a possible association with caries, fluorosis and socioeconomic status.In this cross-sectional study, a representative sample of 779 children with an age of 7 to 9 years ±1 year in primary schools in Dubai were randomly selected and examined by one investigator who had previously been trained and calibrated with the diagnostic criteria of European Academy of Paediatric Dentistry (EAPD) for MIH, caries diagnostic criteria of the World Health Organization (WHO) and Dean's criteria for fluorosis.The prevalence of MIH in Dubai was 7.57% and was almost identical for both genders (female 7.57% and male 7.58%). The caries index was high (2.41±1.7). Children with MIH in Dubai exhibited statistically significantly higher DMFT values than did children without MIH (mean 3.5 ± 1.7 vs 2.3 ± 1.7; p < 0.001). The prevalence of fluorosis was 10.9% with no statistically significant age or gender differences.The prevalence of MIH in Dubai is low. However, the caries and fluorosis values are much higher, which calls for strengthening caries-preventive efforts.

  View details for DOI 10.3290/j.ohpd.a42725

  View details for PubMedID 31225537