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INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIAKULLIYYAH OF DENTISTRY

PHASE 1 YEAR 1

BLOCK 4

2007/2008 Session

Course Code: DEN

Operative Dentistry

Function of dental unit

Prepared by

Dr.Shawfekar

Lecturer

Kulliyyah Of Dentistry

IIUM

Kuantan

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The Function of Dental Unit.

Objectives:1. To identify the special need of dental equipments.

2. To define and demonstrate how to maintain the oral cavity and the equipment utilized in treatment

of the oral cavity.

Outline:

1. The Dental Chair

2. Dental Stools

3. Dental Unit

4. Operating Light

5. Cabinetry

6. Sink7. Dental X-Ray Unit

8. Small equipment

9. Dental Air Compressor

Dental Chairs

The dental is the centre of all clinical activity (Fig-1A,B, C, D). The chair is designed for the operator and the

assistant to work on the patient in the comfortable and efficient manner. The dental chair supports the patients

entire body, in either an upright, supine position (nose and knees on the same plane) or sub supine position

(the head lower than the feet). The dental chair is designed to accommodate both children and adults. It is also

control to move the chair up and dawn, recline the back rest, and raise the seat and a combination button that

automatically recline and raise the patient. The controls are either side o of the chair back or on the floor.

Fig-1A. 2 operatories.

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Figure-1B, Dental Chair with foot controls for adjusting chair.

Fig-1C. Dental chair with side controls for adjusting the chair.

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Fig-1D. Dental chair with foot control.

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Dental Stools

The dental stools are required by the operator and the assistant during most procedures. Ergonomic

studies have resulted in the improved design dental stools to provide comfort and prevent fatigue duringdental procedures. The operators and assistants stools have some similarities but also have several

difference (Fig-2A, 2B)

A. Operators Stool

The operators stool has the following characteristics: Adjustable height

Adjustable back rest

Comfortable seat

Mobility

Broad base

Figure-2A Dental Operators Stool with back support.

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B. Dental Assistant stool

The dental assistants stool has the following characteristics. Adjustable height

Adjustable back rest

Comfortable seat

Mobility

Broad base

Foot rest

Easy to adjust

Fig-2B, Assistants stool with front arm support.

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Fig-3A, 2 operatories.

Figure-3B, The Dental Unit including

handpieces, saliva ejector and HVE

The dental unit (Fig-3A, 3B) consists of handpieces, an air-water syringe, a saliva ejector, an oral evacuator

(HIVE), ultrasonic scaling unit and numerous other options. The dental unit may be fixed to the wall, the

cabinets, or on mobile charts. The unit is position according to the preference of the dentist, whether dentist is

left-handed or right-handed, if he or she routinely works within assistant, and according to the design of the

treatment room. The dental unit is available in three basic modes of delivery (Fig-4A, 4B, 4C).

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1. The rear delivery system is designed with the equipment located behind thepatients head.

2. The side delivery system is designed with the equipment located on the dentistsside. The unit is mounted to a moveable arm or a mobile cart.

3. The

front delivery systemis designed so that is can be pulled over the patients

chest and is located between the dentist and the assistant.

Fig-4A. Rear delivery system.

Fig-4B. Side delivery system

Fig-4C. Front delivery system.

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Mobile carts Sometimes, mobile carts (Fih-5A, 5B) are used to hold delivery systems, including theair-water syringe, oral evacuator, handpieces, and saliva ejector. One cart may be used by both the operator

and the dental assistant with the instrumentation on the appropriate side. Two carts, one on each side of the

dental chair, may be equipped and used. The operators cart is usually set up for two or three dental

handpieces plus an air-water syringe. The assistants carts is usually set up with the air-water syringe, saliva

ejector, and HVE. Carts are designed to be moved easily, provide a work space and some storage, and hold

basic instruments.

Fig-5A. Operators chart with dental handpiece and air-water syringe.

Fig-5B. Assistants chart with saliva ejector, HVE, air-water syringe

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Air-Water syringe: The air water syringe (Fig-6A, 6B) provides air, water, or a combinationspray of air and water. The tip of the syringe is removable and made of either disposable plastic or

autoclavable metal. New barriers are placed on the syringe handle and the tubing for each patient. The controls

for the syringe are on the handle and should be easy to operate with the thumb of one hand. Air, water, and the

combination spray help keep the oral cavity clean and dry and protect tooth from the heat produced by the

handpiece. For easier use, the syringe tips come in several lengths and are slightly angled. To reduce the risk

of retaining oral fluid, flush the air-water syringe with water between patients at beginning and end of the day.

Fig-6A. Air-water syringe. (A) handle, (b) air-water control, (C) removable and

disposable tip.

Fig-6B. Air-water syringe.

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Dental handpieces:There are usually two dental handpiece; low and high speed.The handpieces are attached to hoses that are part of the dental unit. It is important thatthese hoses are not bent or tangled. Each handpiece has two controls. First, the hoseattachment has on/off switch to prevent more than one handpiece from running at once.Second, the speed of handpiece is controlled by a foot pedal called a rheostat. Thedental handpieces are removed after eash patients treatment and are sterilized.at thebeginning and end of the day, the handpiece should be run for several minutes.Between patient, run the handpiece for at least one minute to flush the system (Fig-7A,7B, 7C, 7D, 7E).

Fig-7A.Dental unit. (A) Dental handpieces, (B) Saliva ejector, (C) HVE.

Fig-7B. Contra-angle low speed

handpieces.

Fig-7C. Straight handpieces.

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Fig-7D. High speed handpieces with diamond bur.

Fig-7E. High speed contra-angle handpieces

Ultrasonic Scaler: The ultrasonic scaler is attached to the dental unit. The scater is usedduring prophylaxis and periodontal procedures. Small tips attach to the ultrasonic scaler. The scaler has a

vibrating action that remove hard deposits, such as calculus, and other debris from the teeth (Fig-8).

Fig-8. Ultrasonic scaler with polishing brushes.

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Saliva Ejector: The saliva ejector is used to remove saliva and fluid from the patients mouthslowly. It has a low volume suction that is used during certain procedures, such as fluoride treatments

and under rubber dams. The saliva ejector tip is a thin, flexible, plastic tube that is disposable of aftereach patients treatment. This plastic tip slides into the opening of the saliva ejector hose that part of the

dental unit. There is a small trap located in the saliva ejector that needs to be cleaned routinely (Fig-9 A,

9B).

Fig-9A. Disposable saliva ejectors.

Fig-9B. Saliva ejectors.

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High Volume Evacuation (HVE): The high volume evacuation (HVE) is alsocalled the oral evacuator.It is used by the assistant to remove fluids from the patients mouth. Evacuation

tips are wider tubes that are often bevelled at both ends.Some of the tips are metal and can be sterilized,

but most offices use plastic tips that can be sterilized or disposed of.The evacuation tips fit into the handleof the hose,which is covered with a protective barrier during procedures.The on/off control for the HVE is

on the handle.Each unit has a trap that collects debris from the evacuator. This trap must be changed or

cleanad weekly or as needed. There are cleaning systems available to flush the HVE at the end of the day

and week.

Operating Light

The operating light is attached to the dental chair or mounted to the ceiling. Both the operator and the

assistant should be able to adjust the position of the light. Operating lights have improved in many ways.

They are easier to move, more flexible, and direct less heat on the patient. The light has a control switchfor high and low intensities, an on/off switch, and handles on both sides. The light is attached to extension

arms for positioning over the patients face in order to view either the maxillary or mandibular arch.

The handles and on/off switch are covered with barriers during procedures. The barriers are changed

between each patient. Maintenance includes changing the light bulb occasionally and keeping the heat

shield clean. It is important to follow the manufacturers instructions for both of these procedures (Fig-

10).

Fig-10. Operating light.

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CabinetryMost treatment rooms have some type of cabinetry for storage of supplies and materials used during

treatment. Some dental units are designed in fixed cabinets that surround the patient, operator, and

assistant. These units include cupboards that open from the front and the back for treatment trays, drawers

for materials frequently used, and sinks for both the operator and the assistant. The amount of cabinetry

depends on the size of the room and the dentists preference.

Mobile cabinets are also used in the treatment room. These cabinets come in a variety of designs and

are used for storage and as work space. The mobile cabinet is stored against the wall and then pulled into

position after the patient is seated.

SinkThe treatment room should be designed with sinks in convenient locations for the dentist and the

assistants. Some treatment rooms have to sinks, one on each side of the dental chair. Other treatment

rooms have one sink that is located centrally behind the dental unit for both the dentist and assistant to

use.

The water controls on the sink should be operated by wrist, foot, or knee control. There are light and

motion sensor devices that turn the water on and off automatically when standing in front of the sink the

sinks should be easy to clean and have an area nearby for soap and towel dispensers.

Dental X-Ray UnitA dental x-ray unit used to expose intraoral radiograph is part of most treatment rooms. Sometimes the x-

ray tube head is housed between two rooms with doors on both side for x-ray tube head to slight out into

either room. The controls are found out side the room, so that the dental assistant is not exposed to

radiation. The panoramic machine for exposing extra oral radiograph is usually located in a separate area

out side the treatment room.

Small equipmentThere may be variety of equipments in the treatment room depending on the primary use of the room.

Most rooms have an x-ray view box, curing light, amalgamator, communication system, computerized

intra oral dental camera, and satellite computer.

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X-ray View box: The x-ray view box is used to read and diagnosed radiograph. It consists ofbright light source covered with a frosted surface. X-rays are placed on the frosted surface for clear

viewing (Fig-11).

Fig-11. X-ray view box

Dental Curing Light:A dental curing light is used to cure or set light-cured materials.Many dental products are light cured. The curing light has a small motor that produces the high intensity

light, a wand, a protective shield, a handle, and trigger to turn the light on and off. The curing light used

halogen bulbs. Follow the manufactures instructions when changing the bulb (Fig-12A,B,C,D,E).

Fig-12 A. Light Cure unit

Fig-12B. Light cure unit

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Fig-12C. Light cure unit

Fig-12C. Light Cure set

Fig-12D. Dental curing light.

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Fig-12E. laser curing light.

Amalgamator: The amalgamator is a small machine that mixes dental amalgam and somedental cements. It is placed near the assistant either on the counter or in a drawer (Fig-13A, 13B).

Fig-13A. Amalgamator.

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Fig-13B. Amalgamator

Dental Air Compressor and Central Vacuum System

The air compressor provides compressed air for the handpiece and air for the air-water syringe.

The size of air compressor depends on the number of dental units utilized by the office. Usually,

the compressor is stored away from the main office because of it size and noise level.

The dental vacuum system provides suction for saliva ejector and oral evacuators at each dental

unit. The filters or traps must be cleaned regularly to keep this system working to capicaty. This

system is also stored away from the main office.

Dental office staffs and dental service companies must follow the manufacturers instructions for

maintenance and repairs on the air compressor and the vacuum system. Both units may be set up

on time clocks to run only when the office is open and operating.

Reference:Phinney DJ, Halstead JH, 2000 Delmars Dental Assisting, Delmer Thomson Learning.

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