Four Handed Dentistry

Elimination Elimination is the easiest of the principles of work simplification to implement. A 100% time savings can be realized if one merely eliminates an unnecessary item of equipment, movement, or procedural step. Most dental offices today have realized the necessity of the high velocity suction when using the high speed handpiece.
However, it is unfortunately not uncommon to see cuspidors being placed on many modern dental units. Research shows, utilization of a cuspidor dictates a 14%-18% time-loss factor and creates infection control inefficiencies and risks. In the rare instance that the patient needs to expectorate, a cup can be provided. The dentist can identify many areas where elimination would be appropriate. For example, using pre-set instrument trays reveals what instruments are used routinely during a procedure which ones should be removed from the pre-set tray and placed in a convenient location, should the need for them arise. One should always plan for the usual, not the unusual.
Combination Industry has done the majority of work for dentistry in our efforts to combine instruments. For example, consider the amount of space and confusion saved by the use of double-ended instruments. Also, one should consider uses of the same instrument for different purposes. A small double-ended ball burnisher may be used to mix and place liners, burnish contacts, and post-carve burnish amalgam restorations. This alone will eliminate the need for three or more instruments on a pre-set tray.

Simplification Simplification involves examining a job to determine how it is done, who does it, and when it is performed. The team analyzes their procedures to determine ways in which standardization of their approach would benefit their overall efficiency. By eliminating as many variables as possible, there is a decrease in confusion, a greater team efficiency, and a more productive dental office.
When multiple operatories in a dental office are standardized in equipment and supply arrangement, the team need not concern themselves with identifying where an item is or develop a favorite operatory to the detriment of the others. When an item is not used routinely, it should be placed on a mobile cart (e.g., Ultrasonic scalers, intraoral cameras, etc.), so it can be moved from room to room. However, if an item is used routinely, it ought to be standard in every operatory. The overall effect of implementing this concept of four-handed dentistry is increased efficiency for the dental team. The dentist will also realize decreased muscular stress, and should be able to increase the quality of their patient care through repetition and organization.
EQUIPMENT SELECTION CRITERIA Background The benefits to be expected from practicing the previously covered principals of the concept of four-handed dentistry, can be realized when one strictly adheres to them. However, maximal benefits can be reached only when the equipment used by the team meets the specifications developed by the researchers at the University of Alabama School of Dentistry. This section will present the criteria for selection of several types of dental equipment that are necessary when using this concept of four-handed dentistry. The dental team should evaluate their present equipment, using this criteria, to determine if it meets or falls short of the criteria. As one sees the need to purchase additional equipment, using the criteria will enable the practitioner to acquire equipment compatible with this concept of four-handed dentistry. (Click here to review the Equipment Specifications section of our website)

Operator Stools The operator's and assistant's stools are among the first items one should examine. The principles of four-handed dentistry, include working in the seated position. It is not only necessary that we are seated, we must sit comfortably with balanced posture. Use of an improper stool will require the dentist or assistant to sit in an awkward position, cause damage to the circulation in the lower limbs, and lead to damage to the lower back and heart.

The operator's stool should, of course, be mobile to enable the operator to move in their zone of activity. Even though most dental equipment manufacturers place a five caster base on the operator's, it is not required. The seat must be adequately padded to insure operator comfort and prevent inordinate pressure from being placed on the back of the thigh. The height range of the stools allows the chair to be used by many different operators of varying heights. The adjustments mechanism does not need to be elaborate, since the height of the stool should not vary in a solo private practice. However, if one is in a group practice or uses expanded duty dental assistants, having a stool with rapid adjustment would beneficial. A proper back support should have both vertical and horizontal adjustments and provide positive support even if the operator leans slightly.

Assistant Stools Although the assistant is not required to move within their zone as much as the operator, the assistant stool should have a broad, stable, mobile base with at least five casters. Since the assistant usually positions themselves four to six inches higher than the dentist, the base should provide stability to prevent tipping and possible injury to the assistant and/or patient. The seat should be large and adequately padded to give proper thigh support when the assistant's feet are positioned on the ring of the base.

The assistant's stool has no minimum height but does not need to exceed 27 inches measured from the top of the seat padding to the floor. The reason for this is to preclude the possible instability of the assistant and to allow the assistant to use a standardized mobile cabinet of a pre-set height. The body support of the assistant's stool should be positioned just under the rib cage and will give support when the assistant leans slightly forward toward the mobile or sideways toward the patient. The body support should be constructed so that it does not interfere with instrument transfers and should not be used as an arm rest by the assistant.

Patient's Chairs
	The criteria established for the patient's chair was developed to insure that patients remain comfortable during the procedure and concurrently allow the team to position the patient properly to allow access and visibility of the operating field. Thus, the operating team is better able to maintain their position and posture. One can readily see the need for the back of the patient's chair to be thin and narrow by visualizing the opposite of such a chair back in operation.
If one attempts to use a recliner for a patient's chair, it would not be possible to work with the forearms parallel to the floor or without leaning excessively to gain proper visibility. Though many chairs on the market meet the criteria for thin backs, few are truly narrow enough to preclude the operator having to lean. Always examine the width including upper body support pads or extensions to determine the feasibility of positioning oneself close to the patient without leaning excessively. Manufacturers of patient chairs have developed a variety of methods for providing support for the patient's upper body. Whether the support is in the form of slings, pad or chair extensions, the upper body support must provide complete support for the supine patient without compromising the operator's access. In addition, a rigid, solid frame makes for a more stable, safe platform that flexes less when patients move or shift while in the chair (i.e. crossing their legs so their head bobs up and down). The chair base should allow the seat portion of the chair to be lowered so that it is no more than fourteen inches from the floor. This will allow the dentist to position the patient properly for operations on Mandibular teeth and still work with their forearms parallel to the floor. Some of the newer bases and the older hydraulic bases will not allow one to lower the chair to this extent. The assistant usually seats and positions the patient, however, the chair adjustment controls need to be accessible by both the operator and the assistant to permit either to make necessary minor adjustments. The last criteria for patient chair selection states that the chair base should allow for rotation of the chair. Since many offices have x-ray machine heads in the operatory, having a chair with a rotating base allows the team more flexibility in positioning the patient for various types of radiographs. Although this is not part of the original criteria, one should carefully evaluate the ability of the team to disinfect their stools and the patient's chair. Materials used in upholstering should not allow accumulation of dirt or debris generated during dental procedures. Even though cloth is considered the most comfortable fabric, vinyl is usually selected due to its capability of being cleaned with disinfecting solutions and its long-range durability. Some of the newer chairs even offer a seamless design to allow more thorough disinfecting. However, one should be aware that the seamless design usually offers less cushioning in the seat and back portion because of the manufacturing process.

Mobile Cabinets
	Research shows that the proper use and organization of the mobile cabinet can contribute to 50% of the assistant's efficiency. The mobile cabinet allows the operating team flexibility in positioning cabinetry close to the area of operation. Certainly, the dental cabinet must have casters to provide mobility for ease in positioning.
Oftentimes, operating teams may have cabinets devoted to certain procedures, (e.g., restorative, endodontic, hygiene, etc.) , so the ability of the assistant to move the appropriate cabinet into position is of paramount importance. It should be understood that the mobile cabinet provides easily accessible space for those items of equipment and materials used routinely in the operatory. Those items not used on a routine basis should be placed in auxiliary operatory cabinetry or in a central supply area. It is the responsibility of the chairside assistant to insure that an adequate supply of equipment and materials remain within easy access in the appropriate area of the mobile cabinet. The drawers contain back-up instruments for pre-set trays and additional instruments or supplies commonly used in procedures which one has not elected to place on the pre-set trays. The cabinet provides a work surface over the assistant's lap by one of two means. Ideally, the typical Alabama style cabinet has a cabinet top which moves from front to back, and when positioned over the assistant's legs, provides easy access to items placed in the rear of the cabinet well. Therefore, those items used most frequently should be placed in this position. Supplies less frequently used are placed in the front of the well or in a drawer of the cabinet. The other type cabinet is the North Carolina style which has a top that moves from side to side, thereby exposing the cabinet well to the assistant's right side. Though this provides access to the cabinet, there is the need for additional operatory space on the assistant's side of the chair and there is no provision for an arm rest for the dentist. Either cabinet will work in four-handed dentistry, though the North Carolina style may be more readily adapted to six-handed dentistry if that is the desired method of treatment delivery. It is common, however, that most dental operatories just don't have sufficient space for the North Carolina style cabinet. The dimensions of he cabinet have been determined by research to be 31 inches in height and 14 inches in depth. The width of the cabinet is not specified in the research, but is commonly 22-24 inches. If an assistant were positioned at the highest possible position in an assistant's stool which meets the aforementioned criteria, a 31 inch cabinet would allow proper positioning of the cabinet over the assistant's lap. Since the assistant is usually positioned with their feet off the floor, it is not desirable that the cabinet be so deep that the assistant would have to lean excessively to reach items placed in the he back of the cabinet well. A fourteen inch depth has been shown to give the assistant access, while still providing adequate space for storage of frequently used items of equipment and materials. The final criteria provides for a waste receptacle on the side of the cabinet and an arm support for the operator on the opposite side. The waste receptacle is lined with a plastic headrest cover and holds all waste generated during the procedure. This is of benefit to the dentist who must often separate medical waste from other waste produced in the office. A key, ergonomic element is the arm rest which provides support for the operator's opposing arm. With this support, the operator is not forced to have a third finger rest, thus providing the assistant with better access to the patient's oral cavity. Dental Units The dental unit is the critical system that aids in the control of tubing's attached to the powered instruments (h.p.s.), suction tips and the air/water syringes. Management of these tubing's has been attempted using pulleys, coiled tubing's, and various other retraction systems. In addition to the variety of approaches used in tubing management, there is little uniformity among unit manufacturers as to the placement of these dynamic instruments in relation to the patient's oral cavity. Thus, dentists are forced to use inefficient techniques and awkward postures merely to accommodate their unit. Time and motion studies demonstrate the excessive motion needed to perform procedures when using improperly positioned dental units, usually due to their functional design. Research showed the most convenient and efficient position of the dental unit is the trans-thoracic position. It was also determined that the unit should not be split into operator and assistant sub-units. This eliminated the need for two air-water syringes and gives the chairside assistant convenient access to the handpieces to change burs and transfer handpieces like any other instrument. The criteria for dental units state that the unit should be positioned in the transfer zone but out of the immediate transfer area so that there is convenient access for both the operator and the assistant to all tubing attached instruments without interfering with routine instrument transfers. Thus, all tubing will originate in line with the direction of their use, eliminating excessive forces exerted on the operator's hands by tubing bent at sharp angles. The dental unit must not occupy space needed by the operator or the assistant interfering with either of the team members movements within their zones of activity. The most common problem seen with improper unit positioning is when a unit positioned on the operator's side prevents the usage of the eight o'clock position by the operator, a position that is quite useful when working in the lower arch. Operators faced with this complication oftentimes merely cease using that position due to the inconvenience of moving the unit when they want to change positions. It is truly unfortunate that the type of equipment used will dictate the position of a team rather than equipment facilitating the most efficient and direct approach to the patient's oral cavity. The final criteria for dental units is that they have a trouble-free retraction system which permits the tubing to be extended to any desired distance and returned easily. Manufacturers have had difficulty in developing equipment that meets this criteria. Many have tried without success using coiled tubing's, free hanging tubing's, over the patient "whip-style" units and pulley systems. The unit developed from research at Alabama easily met this criteria and others with a unique patented retraction system which works with gravity, retracting the tubing attached instruments when they are returned to the unit. The resultant dental unit is termed the Dentassist, and is manufactured by Health Science Products in Birmingham, Alabama.

Conclusion The information presented in this article is the result of research completed at the University of Alabama School of Dentistry. This research resulted in the development of criteria for the selection of dental equipment.

It is important to note that the selection criteria did not involve finding ways of making dental operating teams fit existing dental equipment. Rather, equipment was evaluated and developed from the ground up, resulting in equipment for dentist, designed by dentists researching the ergonomics of delivering dental care. Dr. Smith can be reached for questions on clinical technique and dental equipment selection by writing to Health Science Programs at 1000 11th Court West, Birmingham, Alabama 35204, or call 1-800-237-5794. The author wishes to thank Dr. Glen E. Robinson, Mr. Edward J. McDevitt, Dr. Arthur H. Wuehrmann, and the late Gertrude M. Sinnett for their immense contribution to the dental profession. Their research has enabled dentists to become more efficient and productive and has provided a means that enables a dentist to produce optimal dentistry in a timely manner. I would also like to acknowledge Dr. Michael Hughes of the University of Alabama School of Dentistry and Dr. Joseph E. Chasteen of the University of Washington School of Dentistry and others for their dedication in teaching these principles. References Robinson, G.E., Wuermann, A.H., Sinnett, G.M., and McDevitt, E.J. : Four-Handed Dentistry: The Whys and Wherefores. J AM Dent Assoc. 77:573-579, 1968 Editorial: Educators Say Trends Don't Support School Closings. Gen Dent 38: 254-244, 1990 Robinson, G.E., McDevitt,E.J., Sinnett, G.M., and Wuehrmann, A.H.: Four-Handed Dentistry Manual, ed 6. Birmingham, University of Alabama School of Dentistry, 1991 Chasteen, J.E.: Four-Handed Dentistry in Clinical Practice, St. Louis, C.V. Mosby Co., 1978 Chasteen, J.E.: Essentials of Clinical Assisting, ed 4 St. Louis, C.V. Mosby Co., 1989 HSP Partners In Progress 1-800-237-5794 1000 11th Court West, Birmingham, AL. 35204 Web Design By WebNet International A Division Of U*Seek*U*Find