Finger Rest Research Articles

Effect of finger rest positions on upper limb muscle activity during pre-clinical procedures.

This study aimed to observe the effect of different finger rest positions on the muscular activity of the hand, forearm, arm, shoulder, thorax, and neck, as well as on the angular deviation from the neutral position of the neck, trunk, upper arm, and forearm on the working side during pre-clinical procedures. An experimental laboratory study was performed. Response variables were muscle activation of the abductor pollicis, brachioradialis, biceps brachii, deltoid, pectoralis major, and right sternocleidomastoid muscles and angular deviation from the neutral position of the neck, trunk, arm, and forearm during simulated clinical procedures. Independent variable was finger-rest position during cavity preparation (no finger rest, usual rest, and ergonomic rest). Class I cavity preparations (N = 120) were performed on artificial first molars (16, 26, 36, and 46) (N = 120). Muscular activation was assessed by surface electromyography and angular deviations using Software for Postural Assessment (SAPO) version 0.69. One-way analysis of variance and Tukey's or Games-Howell's post-hoc tests were performed (α = 0.05). For the sternocleidomastoid muscle, there was no statistically significant difference between the different rest positions. For the deltoid muscle, work with no finger rest resulted in greater muscle activation (p < 0.001) during work on tooth 36. Regarding the pectoralis major and right brachioradialis muscles, we observed that for both teeth 16 and 26, working with ergonomic rest showed less muscle activation. Muscle activation of the right biceps brachii was higher for work with no rest in both the upper and lower arches, differing significantly only from the usual rest in tooth 16 (p < 0.001), usual rest and ergonomic rest in teeth 26 and 46 (p < 0.001), and only ergonomic rest in tooth 36 (p = 0.044). In the right abductor pollicis muscle, work with ergonomic rest resulted in less muscle activation for cavity preparation in teeth 16, 26, and 36, which was significantly different from work with no rest (p = 0.029, p < 0.001, and p = 0.013, respectively). Regarding angular deviation, it was observed that for tooth 16, there was a greater angular deviation of the arm when performing cavity preparations with no finger rest. For teeth 26 and 46, the ergonomic finger rest provided lower angular deviation from the neutral position of the right arm. For tooth 36, ergonomic rest provided less angular deviation from the neutral neck position. In general, the use of non-active finger rest during simulated cavity preparations, regardless of the type of rest, provided less muscle activation and angular deviation from the neutral position of the body's upper extremity when performing pre-clinical procedures.

Effects of micropipette handle diameter and inclusion of finger rest on basilar thumb joint contact mechanics.

Micropipette users commonly experience problems in the hand and upper limbs. Mechanical factors are thought to contribute to osteoarthritis (OA) initiation and progression in the basilar thumb joint. Finite element analysis can be used to examine the effects of micropipette design on contact mechanics measures within the basilar thumb joint. This pilot study examined the effect of micropipette handle diameter (12mm, 25mm, and 40mm) and the presence of a finger rest on contact area, contact force, and peak contact pressure in the basilar thumb joint. All contact mechanics measures decreased with increasing handle diameter with significant differences between the 12mm diameter and the 40mm diameter handles (contact area down about 30 mm2, contact force down about 15N, and peak pressure down about 1MPa). Decreasing contact mechanics measures with increasing diameter matched our expectations that contact measures would decrease with a more open grip. Contact mechanics measures were higher (p < 0.05) with a finger rest for contact area and force. We expected peak contact pressure and contact area to decrease with the presence of a finger rest. The unexpected outcome may have been due to non-randomized testing order and fatigue during testing.

Dental students' perceptions on a simulated practice using patient-based customised typodonts during the transition from preclinical to clinical education.

Dental students experience difficulties during the transition from preclinical to clinical curriculum. In order to help the students to adapt to the clinical education programme, a simulated practice using patient-based customised models was introduced in this study to prepare for their first clinical practice. This study included 45 third-year predoctoral students (D3 students) who were about to perform the preparation of a single crown abutment on their first patient. After practicing abutment preparation using simulated models and providing the actual treatment to their own patient, the students were surveyed to investigate their perceptions on the simulated practice using the 3D-printed customised typodont model. The statistical analysis of the quantitative data and the thematic analysis of the qualitative data were conducted. Regarding this simulation, more than 80% of the students gave positive feedback on their practice of (a) operative positions and postures, (b) finger rest, (c) occlusal reduction, (d) axial reduction and (e) proximal reduction. Student responses on the open-ended questions about how they perceived the usefulness of this simulation were categorised as "First clinical case," "Patient-based model" and "Realistic simulation environment." In addition, a number of improvements of the simulation were also suggested by the students including the typodont and the manikin. This study gives insights into the significance of simulated practice using patient-based customised typodonts as a transitional education tool and its direction of development in the field of restorative treatments accompanied by irreversible tooth preparations.

Reducing Surgeon's Physical Stress in Minimally Invasive Neurosurgery.

Various minimally invasive approaches are used in neurosurgery. Surgeons must perform nondynamic fine movements in a narrow corridor, so specially designed surgical devices are essential. Unsophisticated instruments may pose potential hazards. The purpose of this study was to assess the factors associated with muscle fatigue during minimally invasive neurosurgery and to investigate whether physical stress can be reduced by refining the devices used. Four physical aspects of a handpiece were investigated: torque of conduits (0.20, 0.28, and 0.37 kgf*cm), shape of hand grip (five types), angle of the nozzle (0, 20, and 40 degrees), and weight balance (neutral, proximal, and distal). To evaluate muscle fatigue, surface electromyography was recorded from the extensor carpi radialis muscle and flexor carpi radialis muscle during a geometric tracing task. The maximum voluntary contraction (MVC) of each muscle and %MVC (muscle contraction during a task/MVC × 100) were used as the indexes of muscle fatigue. The shape of the hand grip significantly reduced %MVC, which is associated with muscle fatigue. The torque of conduits and angle of the nozzle tended to reduce muscle fatigue but not significantly. Weight balance did not affect muscle fatigue. Based on these results, we made two refined models: model α (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9 × 2.0-cm oval section with angled finger rest), and model β (torque of conduits 0.2 kgf*cm, angle of nozzle 20 degrees, neutral balance, hand grip with a 2.9-cm round section with a curved finger rest). The %MVC was significantly decreased with both types (p < 0.05 and p < 0.01, respectively), indicating reduction of muscle fatigue. The geometrically refined surgical device can improve muscle load during surgery and reduce the surgeon's physical stress, thus minimizing the risk of complications.

Relation between Manual Dexterity and the Accuracy of Cavity Preparation

Background: Manual dexterity is important for dentists. However, few studies have investigated the relation between dental skills and manual dexterity. The hypothesis of the present study is that an association exists between manual dexterity and the accuracy of cavity preparation.Methods: Fifty-two dental students (25 males, 27 females) participated in this study. All subjects completed manual dexterity tasks (i.e., grip strength, pinch force, and number of taps made by fingers of the right hand) and a preparation accuracy test using Virtual Reality Systems (VRS, Simodont®). For the preparation test, the cross-block body in Simodont's Manual Dexterity section was used. The associations between erroneous preparations (i.e., errors in the lateral and vertical directions) and the results of manual dexterity tasks were then analyzed and examined.Result: The results revealed that grip strength and number of taps made by the fingers correlated with lateral direction errors. In particular, the number of taps in the first 10 s from the start of tapping made by the third finger, which the participants used as a finger rest during preparation, demonstrated a significant correlation with lateral direction errors.Conclusion: In this work, tapping was revealed to be associated with manual dexterity by quantifying the accuracy of preparation. In addition, the agility of the third finger used as a finger rest appeared to affect accuracy in the lateral direction. VRS is useful not only in developing teaching strategy but also in research on cavity preparation. DOI: 10.21276/aohdr.1828

The efficacy of video monitoring-supported student self-evaluation of dental explorer skills in dental hygiene education.

The objective of this study was to investigate whether having dental hygiene students monitor video recordings of their dental explorer skills is an effective means of proper self-evaluation in dental hygiene education. The study participants comprised students of a dental hygiene training school who had completed a module on explorer skills using models, and a dental hygiene instructor who was in charge of lessons. Questions regarding 'posture', 'grip', 'finger rest' and 'operation' were set to evaluate explorer skills. Participants rated each item on a two-point scale: 'competent (1)' or 'not competent (0)'. The total score was calculated for each evaluation item in evaluations by students with and without video monitoring, and in evaluations by the instructor with video monitoring. Mean scores for students with and without video monitoring were compared using a t-test, while intraclass correlation coefficients were found by reliability analysis of student and instructor evaluations. A total of 37 students and one instructor were subject to analysis. The mean score for evaluations with and without video monitoring differed significantly for posture (P < 0.0001), finger rest (P = 0.0006) and operation (P < 0.0001). The intraclass correlation coefficient between students and instructors for evaluations with video monitoring ranged from 0.90 to 0.97 for the four evaluation items. The results of this study suggested that having students monitor video recordings of their own explorer skills may be an effective means of proper self-evaluation in specialized basic education using models.

Preliminary evaluation of a virtual reality dental simulation system on drilling operation.

To evaluate the fidelity of the iDental system and investigate its utility and performance on simulated drilling operations, user studies consisting of objective and subjective evaluations were performed. A voxel-based drilling simulation sub-system in the iDental system was employed for evaluation. Twenty participants were enrolled to take part in the experiments and were divided into two groups: novice and resident. A combined evaluation method including objective and subjective methods was employed. The objective evaluation included two dental drilling tasks: caries removal operation and pulp chamber opening operation. In the subjective method, participants were required to complete a questionnaire to evaluate the fidelity of the system after the operation task. Based on the structured global assessment scales in the questionnaire, the average subjective evaluation scores of the proposed metrics were greater than 4.5, demonstrating that the system operated above medium fidelity. Dentists expressed great interest and positive attitudes toward the potential of the iDental system. The objective evaluation data including time spent and the volume of removed healthy and carious tissue were obtained. Although no significant differences could be found between the two groups, the volume of removed caries and the depth of pulp chamber insertion manifested small standard deviations. Evaluation results illustrated that dentists were willing to use the virtual reality training system. Several future research topics were identified, including increasing the task difficulty, improving the system fidelity and introducing appropriate finger rest points.

A novel field barrier method for patients with an impaired glossopalatal seal

aLecturer, Section of Prosthetic Dentistry, School of Dentistry. bAssociate Professor, Section of Prosthetic Dentistry, School of Dentistry; Vice-Director, Department of Dentistry, National Taiwan University Hospital. (J Prosthet Dent 2013;109:206-207) The voluntary glossopalatal seal is formed when the soft palate and posterior tongue pinch together and can prevent premature spillage of fluid into the oropharynx during the preparation stage for swallowing.1,2 During routine dental procedures with water spray, patients control their glossopalatal seal to hold the water in the mouth until removed by an evacuator. However, patients whose glossopalatal seal is impaired by congenital or acquired soft palatal defects, tongue defects, or neurologic diseases affecting soft palate and tongue control often choke or cannot tolerate procedures even with the use of special high-volume evacuation. Although special evacuators such as the Svedopter (Svedia Dental-Industri AB, Enkoping, Sweden) or the Speejector (Pulpdent Corp, Watertown, Mass) are intended to retract the tongue, isolate the teeth, aid in fluid removal, and maintain a dry operation field, they cannot prevent water from reaching the back of the oral cavity and oropharynx. The application of a rubber dam or a throat pack as a barrier to the oropharynx has been suggested.3 However, a rubber dam is sometimes inapplicable or impedimental, and a throat pack does not work well during ultrasonic scaling or tooth preparation of the most distal or solitary abutment. For those situations, a technique to prevent water spilling into the oropharynx of patients with an impaired glossopalatal seal is presented. In this technique, the plastic sheet functions as a field barrier to prevent water spilling directly into the oropharynx. In procedures with profuse water irrigation, the passively seated plastic sheet in the oral cavity can act as a large reservoir to contain a large quantity of water before it is removed by the suction tube. The clinician can design and customize the rigid, frame-like plate according to the operation area and the location for finger rest.

The Effects of Finger Rest Positions on Hand Muscle Load and Pinch Force in Simulated Dental Hygiene Work

One of the techniques taught in dental and dental hygiene programs is to use finger rests to stabilize the instrument while performing dental scaling or other types of dental work. It is believed that finger rests may also reduce muscle stress and prevent injury due to muscle fatigue. In this study the effects of three different finger rest positions on hand muscle activity and thumb pinch force were compared. Twelve predental students performed simulated dental scaling tasks on a manikin using three different finger rest positions: 1) no finger rest, 2) one finger rest, and 3) two finger rests. Muscle activity and thumb pinch force were measured by surface electromyography and a pressure sensor, respectively. Using two finger rests was always associated with reduced thumb pinch force and muscle activity, as compared to not using any finger rests (p<0.05), while using one finger rest reduced thumb pinch force and muscle activity in most cases. Hence, using finger rests plays an important role in reducing the muscle load of the hand in students performing simulated dental hygiene work. It is concluded that dental and dental hygiene students may benefit from instructions for using finger rests at an early stage of their clinical training. Including biomechanical and ergonomic principles in dental and dental hygiene curricula will raise awareness of ergonomics among dental practitioners and help them incorporate these principles into daily practice.

Finger-Pressure Waveforms Measured on Clynes' Sentograph Distinguish among Emotions

We examined the transient finger-pressure when subjects were exposed to the schematic faces which depict "anger," "joy," "sadness," and "no emotion," and to two nonfacial stimuli. In Exp. 1, nine undergraduate women were asked to discriminate between those target stimuli and the nontarget stimuli by pressing on the finger rest of Clynes' Sentograph, without informing subjects that this experiment was to measure emotions. In Exp. 2, the same subjects were asked to express their feelings evoked by the schematic faces by pressing on the finger rest. Results indicate that, even on the discrimination task, the differentiation in the finger-pressure waveforms among emotions was observed. Such differentiation suggests the possibility of measuring the expression of emotions with finger pressure even when the subjects are not aware their emotions are being measured. The identifiable characteristics of the waveforms are the long duration for "sadness" and the strong intensity of pressure for "anger."

Flute instrument digit rest and spacer

First Page

NEW INSTRUMENT FOR USE IN RHINOPLASTIC SURGERY

The instrument was presented before the Otolaryngological Section of the Medical Society of the County of Kings and the Academy of Medicine of Brooklyn on Nov. 10, 1943. It was also presented at the annual meeting of the American Rhinological Society for the Advancement of Plastic and Reconstructive Surgery and the Academy of Medicine of New York on Nov. 12, 1943. The new instrument has been devised to serve a twofold purpose. One end enables the rhinoplastic surgeon to (1) present to direct view the lower lateral cartilage and (2) to section it exactly as desired with one sweep of the knife. Below is shown the left lateral view. Note (<i>a</i>) hook, (<i>b</i>) flanger elevator, (<i>c</i>) angulated rest plate, (<i>d</i>) button finger rest, (<i>e</i>) abrupt taper and (<i>f</i>) pivot rest. It eliminates any danger fo the knife slipping, any deviation from the predetermined line of incision or any nicking of