Isolation of the Operating Field

The goals of operating field isolation are moisture control, retraction, and harm prevention.

Moisture Control : Operative dentistry can not be executed properly unless the moisture in the mouth is controlled. Moisture

control refers to excluding sulcular fluid, saliva and gingival bleeding from the operating field. It also refers to preventing the handpiece spray and restorative debris from being swallowed or aspirated by the patient. The rubber dam, suction devices, and

absorbents are varyingly effective in moisture control.

So the reasons for moisture control are 1. For the patient's comfort and to improve the dentist's vision.

2. To prevent extraneous infection by saliva that teeming with microorganisms.3. To prevent contamination of restorative materials and tooth with saliva.

Retraction and Access: This provides maximal exposure of the operating site and usually involves maintaining an open mouth and depressing or retracting the

gingival tissue, tongue, lips and cheek. The rubber dam, high-volume evacuator, absorbents, retraction cord, and mouth prop are used for retraction and access.

Harm Prevention: An axiom taught to every member of the health profession is “Do no harm " and an important consideration of isolating the operating field is preventing the

patient from being harmed during the operation. Small instruments and restorative debris can be aspirated or swallowed. Soft tissue can be damaged accidentally. As with

moisture control and retraction, a rubber dam, suction devices, absorbents, and occasional use of a mouth prop contribute not only to harm prevention but also to

patient comfort and operator efficiency.

Local Anesthesia : It plays a role in eliminating the discomfort of dental treatment and controlling moisture. Use of these agents reduces

salivation, apparently because the patient is more comfortable, less anxious, and less sensitive to oral stimuli, thus reducing salivary flow. Local

anesthetics incorporating a vasoconstrictor also reduce blood flow, thus helping to control hemorrhage at the operating site.

1. Rubber Dam: The use of rubber dam ensures appropriate dryness of the teeth and improves the quality of clinical restorative dentistry. This method gives the most

complete control over moisture in the mouth.Advantages of rubber dam:

1. Complete isolation of the teeth from saliva, blood , gingival fluid is possible. This is important with all restorations especially with adhesive restorative materials.

2. Improved visibility and access to the operating site resulting in good operating efficiency.

3. Aids isolation from bacteria in saliva so it is indicated when infection from the rest of the mouth must be excluded for example, during direct and indirect pulp capping.4. Protects the patient from swallowing or inhaling instruments or materials like

amalgam fragment, wedges, pins ….ect.5. Saving of time and promotes more efficient treatment.

6. Cross- infection control

Disadvantages : Time consumption and patient objection are the most frequently quoted disadvantages. However, these concerns are reduced

with the use of a simplified technique for application and removal. Certain oral conditions may preclude its use like:

1. Teeth that have not erupted sufficiently to support a retainer.2. Some third molars.

3. Extremely malpositioned teeth. In addition, patient suffering from asthma and in rare instances when the patient can not tolerate it because of psychological reasons or latex

allergy.

1. Rubber dam: is supplied in ready cut square sheets ( 5X5 inch, 6x6 inch ). The rubber is resistant to tearing and it grips the teeth well and retracts gingival

tissue. A dark color green, blue is preferred because it contrasts well with the teeth. They are available in various thicknesses (thin-weight, medium and

heavy).2. Rubber dam punch : It must give clean hole without any tearing. Some

punches have holes of varying diameters; the size of the hole depends on the tooth to be treated.

3. Clamps: Metal clips, which fit the neck of the tooth and hold rubber dam in position, and may enhance gingival retraction. Different types are available:

BW molar clamp wingless (for well erupted)K molar clamp winged

E winged for anterior teeth EW wingless for anterior teeth

AW molar, wingless (partially erupted tooth)C cervical clamp for cervical cavity

4. Clamp forceps: For positioning and removing the clamp5. Rubber dam holder: Holds the free edges of the sheet of the rubber

and prevents them from falling into the mouth or back against the patient's face (retracts and stabilize). Several designs are available , like

metal and plastic types.6. Lubricant : A water – soluble lubricant applied in the area of the

punched holes for reducing the friction between the rubber dam and the teeth.

7. Dental tape : This can be used to carry the rubber past tight contact points.

2. Cotton Roll Isolation and Cellulose Waffers ( Pads ) : Such absorbents are used to absorb saliva and other fluids. They are

helpful in these situations :1. Short period of isolation (e.g. examination, sealant placement,

polishing…ect.2. As alternatives when rubber dam application is impractical or

impossible.3. When we need acceptable dryness for procedures such as

impression taking and cementation. Mostly we use absorbents with saliva ejector. They are placed in the

upper sulcus close to the orifice of the parotid duct, in the lingual sulcus close to the orifices of the submandibular and sublingual ducts, and in the lower buccal sulcus. Several commercial devices for holding

cotton rolls in position are available.

B. High – Volume Evacuators and Saliva Ejectors : Fluids can be evacuated from the mouth either by high-volume evacuators or saliva ejectors. When a high – speed handpiece is used, air-water spray is supplied through the head of the hand-piece to wash the operating site and to act as a coolant for the bur and the tooth, so a high-volume evacuator is preferred for suctioning

water and debris from the mouth because saliva ejectors remove water slowly and have a little capacity for picking up solids.

The combined use of water spray and a high-volume evacuator during cutting has the following advantages:

1. Remove cutting materials as well as other debris from the operating site.2. A washed operating field improves access and visibility.

3. There is no dehydration of the oral tissues.4. Quadrant dentistry is facilitated.

5. Without an anesthetic, the patient experiences less pain.6. Pauses that are sometimes annoying and time consuming are eliminated

7. Precious metals are more readily evacuated. The tip of the evacuator is placed just distal to the tooth to be prepared. The saliva ejector removes saliva that collect on the floor of the mouth, it is

used in conjunction with sponges, cotton rolls and rubber dam. The tip of the ejector must be smooth, made from a non-irritating

material. Disposable, inexpensive plastic ejectors that may be shaped by bending with fingers are available. It's held by the patient and should be

placed to prevent occluding its tip with tissue from the floor of the mouth.

C. Retraction Cord : When properly applied, retraction cord often can be used for isolation and retraction in the direct procedures of treatment of accessible subgingival areas and in indirect procedures involving gingival margins. Most

brands are available with and without vasoconstrictor epinephrine, which also acts to control sulcular fluids, the proper diameter should be selected for each

situation.

D. Mirror and Evacuator Tip Retraction : A secondary function of the mirror and evacuator tip is to retract the cheek, lip and tongue , particularly when a

rubber dam is not used.

E. Mouth Props : A potential aid to restorative procedures on posterior teeth ( for a lengthy appointment ) . A prop should establish and maintain suitable

mouth opening, thereby relieving the patien's muscles of this task, which often produces fatigue and pain. Mouth props of different designs and

materials are available, either as block type or ratchet type.

F. Drugs : The use of durgs to control salivation is rarely indicated in restorative dentistry and is generally limited to atropine. The operator should

be familiar with it's indications and contraindications.

Thanks