Work-related musculoskeletal disorders (MSDs) are the most common occupational disorders around the world. The risk factors for developing MSDs include individual factors, physical requirements at the workplace, organizational and psychosocial factors; their prevalence varies considerably across occupations and working populations. Work-related upper limb disorders (WRULDs) are the musculoskeletal disorders of the neck and upper limbs [1]. Dental hygienists, especially those who are older and female, have a higher risk than other workers of developing upper-limb musculoskeletal disorders (WRULDs), like carpal tunnel syndrome [2-13]. Prevention of MSDs is based on eliminating or reducing risk factors, which may be subdivided into factors linked to the worker, the type of work, the working position, and the instrument used [3,5,12-19]. Correct positioning of hygienist and patient plays a fundamental role in efficient clinical treatment, and should prevent harm to the patient and limit disorders to the hygienist’s musculoskeletal system [5,8,10,12-14,16-19]. Dental scaling is carried out with manual or mechanical instruments (e.g. sonic scaler system); root-planning with manual instruments, e.g. series of Gracey curettes, by pulling the working blade along the surface of dental root with a complex movement involving fingers, wrist and forearm [20]. The manual instruments used by dental hygienists for periodontal scaling and root-planning, their main occupation, comprise a hand-piece, a shank linking the hand-piece to the working tip, and a working tip or blade. The hand-piece is the part gripped during use and it may be of various shapes and sizes [10,20-22]. How and how firmly the hygienist holds the hand-piece when working influence the clinical procedure, but also affect his/her rate of tiring [2-6,14,15]. A correct grip gives the hygienist positive control over the instrument, providing balance and flexibility during movements, decreasing the risk of trauma to the patient’s teeth and periodontal tissues, while improving the hygienist’s tactile sensitivity and preventing tiring of the fingers, wrist and arms [5,14, 15,17,18,20-24]. Pinch force during dental scaling and root-planning is influenced by characteristics of handpieces of instruments: thus these characteristics are important risk factors for developing WRULDs [2-5,14,15, 22]. This study is the continuation of our previous work [25] which assessed the perceived satisfaction in using three different types of hand-piece of manual instruments (Gracey curettes) used for manual root planning. We have first evaluated the physical characteristics of the hand-pieces (section, external surface, diameter and weight) of three Gracey curette and subsequently we have recorded, through a questionnaire, the subjective impressions (perceived efficacy, safety, comfort and overall acceptability) expressed by some students of a Hygienist Dental School during work sessions in which the test instruments were used.