Blast-induced traumatic brain injury has emerged as a “signature injury” in combat casualty care. Present combat helmets are designed primarily to protect against ballistic and blunt impacts, but the current issue with helmets is protection concerning blasts. In order to delineate the blast wave attenuating capability of the Advanced Combat Helmet (ACH), a finite element (FE) study was undertaken to evaluate the head response against blast loadings with and without helmet using a partially validated FE model of the human head and ACH. Four levels of overpressures (0.27–0.66 MPa) from the Bowen’s lung iso-damage threshold curves were used to simulate blast insults. Effectiveness of the helmet with respect to head orientation was also investigated. The resulting biomechanical responses of the brain to blast threats were compared for human head with and without the helmet. For all Bowen’s cases, the peak intracranial pressures (ICP) in the head ranged from 0.68 to 1.8 MPa in the coup cortical region. ACH was found to mitigate ICP in the head by 10–35%. Helmeted head resulted in 30% lower average peak brain strains and product of strain and strain rate. Among three blast loading directions with ACH, highest reduction in peak ICP (44%) was due to backward blasts whereas the lowest reduction in peak ICP and brain strains was due to forward blast (27%). The biomechanical responses of a human head to primary blast insult exhibited directional sensitivity owing to the different geometry contours and coverage of the helmet construction and asymmetric anatomy of the head. Thus, direction-specific tolerances are needed in helmet design in order to offer omni-directional protection for the human head. The blasts of varying peak overpressures and durations that are believed to produce the same level of lung injury produce different levels of mechanical responses in the brain, and hence “iso-damage” curves for brain injury are likely different than the Bowen curves for lung injury.

Dentists, as well as other dental personnel are constantly exposed to a number of specific occupational hazards. These cause the appearance of various ailments, specific to the profession, which develop and intensify with years. In many cases they result in diseases and disease complexes, some of which are regarded as occupational illnesses. Relying on relevant literature, the present paper discusses occupational hazards like stressful situations, latex hypersensitivity, allergic reactions due to various dental materials, exposure to radiation (ionizing and non-ionizing), percutaneous exposure incidents (PEI), hazard due to nitrous oxide gas, as well as factors leading to the musculoskeletal system diseases and diseases of the peripheral nervous system. Awareness regarding these occupational hazards and implementation of preventive strategies can provide a safe working environment for all the dental personnel. There is also a need for continuing dental education programs in dentistry so that dentists can update themselves with the latest and newer techniques and materials.

Objective: To measure and assess the noise levels produced by various dental equipments in different areas of a dental institution and to recommend improvements if noise levels are not within permissible limits. Material and Methods: Sound levels were measured at three different areas of a dental institution where learning and teaching activities are organized. The sound level was measured using a sound level meter known as ‘decibulolmeter’. In each area the noise level was assessed at two positions-one, at 6 inches from the operators ear and second, at the chairside instrument trolley. Noise levels were also assessed from a central location of the clinic area when multiple equipments were in operation simultaneously. Results: Dental laboratory machine, dental hand-piece, ultrasonic scalers, amalgamators, high speed evacuation, and other items produce noise at different sound levels which is appreciable. The noise levels generated varied between 72.6 dB in pre-clinics and 87.2 dB in prosthesis laboratory. The results are comparable to the results of other studies which are conducted elsewhere. Although the risk to the dentists is lesser, but damage to the hearing is possible over prolonged periods. Conclusion: Higher noise levels are potentially hazardous to the persons working in such environments especially in the laboratory areas where noise levels are exceeding the permissible limits. Key words:Noise level, equipment, hearing loss, risk, working areas.

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