Periodontal instruments are designed for specific purposes such as removing calculus, planing root surfaces, curetting the gingiva, and removing diseased tissue. On first investigation, the variety of instruments available for similar purposes appears confusing. With experience, however, clinicians select a relatively small set that fulfills all requirements.
3. Scaling, root-planing, and curettage instruments are used for removal of biofilm and calcified deposits from the crown and root of a tooth, removal of altered cementum from the subgingival root surface, and debridement of the soft tissue lining the pocket. Scaling and curettage instruments are classified as follows:
The wearing and cutting qualities of some types of steel used in periodontal instruments have been tested,83,84,146 but specifications vary among manufacturers.146 Stainless steel is used most often in instrument manufacture. High-carbon-content steel instruments are also available and are considered by some clinicians to be superior.
Each group of instruments has characteristic features; individual therapists often develop variations with which they operate most effectively. Small instruments are recommended to fit into periodontal pockets without injuring the soft tissues.109,111,112,163
Periodontal probes are used to measure the depth of pockets and to determine their configuration. The typical probe is a tapered, rodlike instrument calibrated in millimeters, with a blunt, rounded tip (Figure 46-2). There are several other designs with various millimeter calibrations (Figure 46-3). The World Health Organization (WHO) probe has millimeter markings and a small, round ball at the tip (Figure 46-3, E). Ideally, these probes are thin, and the shank is angled to allow easy insertion into the pocket. Furcation areas can best be evaluated with the curved, blunt Nabers probe (Figure 46-4).
When measuring a pocket, the probe is inserted with a firm, gentle pressure to the bottom of the pocket. The shank should be aligned with the long axis of the tooth surface to be probed. Several measurements are made to determine the level of attachment along the surface of the tooth.
Explorers are used to locate subgingival deposits and carious areas and to check the smoothness of the root surfaces after root planing. Explorers are designed with different shapes and angles, with various uses (Figure 46-5), as well as limitations (Figure 46-6). The periodontal probe can also be useful in the detection of subgingival deposits (Figure 46-6, D).
Sickle scalers have a flat surface and two cutting edges that converge in a sharply pointed tip. The shape of the instrument makes the tip strong so that it will not break off during use (Figure 46-8). The sickle scaler is used primarily to remove supragingival calculus (Figure 46-9). Because of the design of this instrument, it is difficult to insert a large sickle blade under the gingiva without damaging the surrounding gingival tissues (Figure 46-10). Small, curved sickle scaler blades such as the 204SD can be inserted under ledges of calculus several millimeters below the gingiva. Sickle scalers are used with a pull stroke.
It is important to note that sickle scalers with the same basic design can be obtained with different blade sizes and shank types to adapt to specific uses. The U15/30 (Figure 46-11), Ball, and Indiana University sickle scalers are large. The Jaquette sickle scalers #1, 2, and 3 have medium-size blades. The curved 204 posterior sickle scalers are available with large, medium, or small blades (Figure 46-12). The Montana Jack sickle scaler and the Nevi 2, Nevi 3, and Nevi 4 curved posterior sickle scalers are all thin enough to be inserted several millimeters subgingivally for removal of light to moderate ledges of calculus. The selection of these instruments should be based on the area to be scaled. Sickle scalers with straight shanks are designed for use on anterior teeth and premolars. Sickle scalers with contra-angled shanks adapt to posterior teeth.
The curette is the instrument of choice for removing deep subgingival calculus, root planing altered cementum, and removing the soft tissue lining the periodontal pocket (Figure 46-13). Each working end has a cutting edge on both sides of the blade and a rounded toe. The curette is finer than the sickle scalers and does not have any sharp points or corners other than the cutting edges of the blade (Figure 46-14). Therefore curettes can be adapted and provide good access to deep pockets, with minimal soft tissue trauma (see Figure 46-10). In cross-section, the blade appears semicircular with a convex base. The lateral border of the convex base forms a cutting edge with the face of the semicircular blade. There are cutting edges on both sides of the blade. Both single- and double-end curettes may be obtained, depending on the preference of the operator.
As shown in Figure 46-10, the curved blade and rounded toe of the curette allow the blade to adapt better to the root surface, unlike the straight design and pointed end of a sickle scaler, which can cause tissue laceration and trauma. There are two basic types of curettes: universal and area specific.
Universal curettes have cutting edges that may be inserted in most areas of the dentition by altering and adapting the finger rest, fulcrum, and hand position of the operator. The blade size and the angle and length of the shank may vary, but the face of the blade of every universal curette is at a 90-degree angle (perpendicular) to the lower shank when seen in cross-section from the tip (Figure 46-15, A). The blade of the universal curette is curved in one direction from the head of the blade to the toe. The Barnhart curettes #1-2 and 5-6 and the Columbia curettes #13-14, 2R-2L, and 4R-4L (Figures 46-16 and 46-17, A) are examples of universal curettes. Other popular universal curettes are the Younger-Good #7-8, McCall’s #17-18, and the Indiana University #17-18 (Figure 46-17, B).
Gracey curettes are representative of the area-specific curettes, a set of several instruments designed and angled to adapt to specific anatomic areas of the dentition (Figure 46-18). These curettes and their modifications are probably the best instruments for subgingival scaling and root planing because they provide the best adaptation to complex root anatomy.
Single-ended Gracey curettes can also be obtained; a set of these curettes comprises 14 instruments. Although these curettes are designed to be used in specific areas, an experienced operator can adapt each instrument for use in several different areas by altering the position of his or her hand and the position of the patient.
The Gracey curettes also differ from the universal curettes in that the blade is not at a 90-degree angle to the lower shank. The term offset blade is used to describe Gracey curettes because they are angled approximately 60 to 70 degrees from the lower shank (see Figure 46-15, B). This unique angulation allows the blade to be inserted in the precise position necessary for subgingival scaling and root planing, provided that the lower shank is parallel with the long axis of the tooth surface being scaled.
Area-specific curettes also have a curved blade. Whereas the blade of the universal curette is curved in one direction (Figure 46-21, A), the Gracey blade is curved from head to toe and also along the side of the cutting edge (Figure 46-21, B). Thus only a pull stroke can be used. Table 46-1 lists some of the major differences between Gracey (area-specific) curettes and universal curettes.
|Gracey Curette||Universal Curette|
|Area of use||Set of many curettes designed for specific areas and surfaces.||One curette designed for all areas and surfaces.|
|Use||One cutting edge used; work with outer edge only.||Both cutting edges used; work with either outer or inner edge.|
|Curvature||Curved in two planes; blade curves up and to the side.||Curved in one plane; blade curves up, not to the side.|
|Blade angle||Offset blade; face of blade beveled at 60 degrees to shank.||Blade not offset; face of blade beveled at 90 degrees to shank.|
Modified from Pattison G, Pattison A: Periodontal instrumentation, ed 2, Norwalk, CT, 1992, Appleton & Lange.
Gracey curettes are available with either a “rigid” or a “finishing” type of shank. The rigid Gracey has a larger, stronger, and less flexible shank and blade than the standard finishing Gracey. The rigid shank allows the removal of moderate to heavy calculus without using a separate set of heavy scalers, such as sickles and hoes. Although some clinicians prefer the enhanced tactile sensitivity that the flexible shank of the finishing Gracey provides, both types of Gracey curettes are suitable for root planing.
Recent additions to the Gracey curette set have been the Gracey #15-16 and 17-18. The Gracey #15-16 is a modification of the standard #11-12 and is designed for the mesial surfaces of posterior teeth (Figure 46-22). It consists of a Gracey #11-12 blade combined with the more acutely angled #13-14 shank. When the clinician is using an intraoral finger rest, it is often difficult to position the lower shank of the Gracey #11-12 so that it is parallel with the mesial surfaces of the posterior teeth, especially on the mandibular molars. The new shank angulation of the Gracey #15-16 allows better adaptation to posterior mesial surfaces from a front position with intraoral rests. If alternative fulcrums, such as extraoral or opposite-arch rests, are used, the Gracey #11-12 works well and the new #15-16 is not essential. The Gracey #17-18 is a modification of the #13-14. It has a terminal shank elongated by 3 mm and a more accentuated angulation of the shank to provide complete occlusal clearance and better access to all posterior distal surfaces. The horizontal handle position minimizes interference from opposing arches and allows a more relaxed hand position when scaling distal surfaces. In addition, the blade is 1 mm shorter to allow better adaptation of the blade to distal tooth surfaces.
Extended-shank curettes, such as the After Five curettes (Hu-Friedy, Chicago), are modifications of the standard Gracey curette design. The terminal shank is 3 mm longer, allowing extension into deeper periodontal pockets of 5 mm or more (Figures 46-23 and 46-24). Other features of the After Five curette include a thinned blade for smoother subgingival insertion and reduced tissue distention and a large-diameter, tapered shank. All standard Gracey numbers except for the #9-10 (i.e., #1-2, #3-4, #5-6, #7-8, #11-12, or #13-14) are available in the After Five series. The After Five curettes are available in finishing or rigid designs. For heavy or tenacious calculus removal, rigid After Five curettes should be used. For light scaling or deplaquing in a periodontal maintenance patient, the thinner, finishing After Five curettes will insert subgingivally more easily.
Mini-bladed curettes, such as the Hu-Friedy Mini Five curettes, are modifications of the After Five curettes. The Mini Five curettes feature blades that are half the length of the After Five or standard Gracey curettes (Figure 46-25). The shorter blade allows easier insertion and adaptation in deep, narrow pockets; furcations; developmental grooves; line angles; and deep, tight, facial, lingual, or palatal pockets. In any area in which root morphology or tight tissue prevents full insertion of the standard Gracey or After Five blade, the Mini Five curettes can be used with vertical strokes, with reduced tissue distention, and without tissue trauma (Figure 46-26).
In the past the only solution in most of these areas of difficult access was to use the Gracey curettes with a toe-down horizontal stroke. The Mini Five curettes, along with other short-bladed instruments relatively recently introduced, open a new chapter in the history of root instrumentation by allowing access to areas that previously were extremely difficult or impossible to reach with standard instruments. The Mini Five curettes are available in both finishing and rigid designs. Rigid Mini Five curettes are recommended for calculus removal. The more flexible, shanked, finishing Mini Five curettes are appropriate for light scaling and deplaquing in periodontal maintenance patients with tight pockets. As with the After Five series, the Mini Five curettes are available in all standard Gracey numbers, except the #9-10.
The recently introduced Micro Mini Five Gracey curettes (Hu-Friedy, Chicago) have blades that are 20% thinner and smaller than the Mini Five curettes (Figures 46-27 and 46-28) These are the smallest of all curettes, and they provide exceptional access and adaptation to tight, deep, or narrow pockets; narrow furcations; developmental depressions; line angles; and deep pockets on facial, lingual, or palatal surfaces. In areas in which root morphology or tight, thin tissue prevents easy insertion of other mini-bladed curettes, the Micro Mini Five curettes can be used with vertical strokes without causing tissue distension or tissue trauma.
The Gracey Curvettes are another set of four mini-bladed curettes; the Sub-0 and the #1-2 are used for anterior teeth and premolars, the #11-12 is used for posterior mesial surfaces, and the #13-14 for posterior distal surfaces. The blade length of these instruments is 50% shorter than that of the conventional Gracey curette, and the blade has been curved slightly upward (Figure 46-29). This curvature allows the Gracey Curvettes to adapt more closely to the tooth surface than any other curettes, especially on the anterior teeth and on line angles (Figure 46-30). However, this curvature also carries the risk of gouging or “grooving” into the root surfaces on the proximal surfaces of the posterior teeth when the Gracey Curvette #11-12 or 13-14 is used. Additional features that represent improvements on the standard Gracey curettes are a precision-balanced blade tip in direct alignment with the handle, a blade tip perpendicular to the handle, and a shank closer to parallel with the handle.
The Langer and Mini Langer curettes are a set of three curettes combining the shank design of the standard Gracey #5-6, 11-12, and 13-14 curettes with a universal blade honed at 90 degrees rather than the offset blade of the Gracey curette. This marriage of the Gracey and universal curette designs allows the advantages of the area-specific shank to be combined with the versatility of the universal curette blade. The Langer #5-6 curette adapts to the mesial and distal surfaces of anterior teeth; the Langer #1-2 curette (Gracey #11-12 shank) adapts to the mesial and distal surfaces of mandibular posterior teeth; and the Langer #3-4 curette (Gracey #13-14 shank) adapts to the mesial and distal surfaces of maxillary posterior teeth (Figure 46-32). These instruments can be adapted to both mesial and distal tooth surfaces without changing instruments. The standard Langer curette shanks are heavier than a finishing Gracey but less rigid than the rigid Gracey. Langer curettes are also available with either rigid or finishing shanks and can be obtained in the extended-shank (After Five) and mini-bladed (Mini Five) versions.
The Schwartz Periotrievers are a set of two double-ended, highly magnetized instruments designed for the retrieval of broken instrument tips from the periodontal pocket (Figures 46-33 and 46-34). They are indispensable when the clinician has broken a curette tip in a furcation or deep pocket.138
Several different companies are manufacturing plastic and titanium instruments for use on titanium and other implant abutment materials. It is important that plastic or titanium instruments be used to avoid scarring and permanent damage to the implants* (Figures 46-35, 46-36, and 46-37).
Hoe scalers are used for scaling of ledges or rings of calculus (Figure 46-38). The blade is bent at a 99-degree angle; the cutting edge is formed by the junction of the flattened terminal surface with the inner aspect of the blade. The cutting edge is beveled at 45 degrees. The blade is slightly bowed so that it can maintain contact at two points on a convex surface. The back of the blade is rounded, and the blade has been reduced to minimal thickness to permit access to the roots without interference from the adjacent tissues.
1. The blade is inserted to the base of the periodontal pocket so that it makes two-point contact with the tooth (see Figure 46-38). This stabilizes the instrument and prevents nicking of the root.
Files have a series of blades on a base (Figure 46-39). Their primary function is to fracture or crush large deposits of tenacious calculus or burnished sheets of calculus. Files can easily gouge and roughen root surfaces when used improperly. Therefore they are not suitable for fine scaling and root planing. Mini-bladed curettes are currently preferred for fine scaling in areas where files were once used. Files are sometimes used for removing overhanging margins of dental restorations.
The chisel scaler, designed for the proximal surfaces of teeth too closely spaced to permit the use of other scalers, is usually used in the anterior part of the mouth. It is a double-ended instrument with a curved shank at one end and a straight shank at the other (see Figure 46-39); the blades are slightly curved and have a straight cutting edge beveled at 45 degrees.
The chisel is inserted from the facial surface. The slight curve of the blade makes it possible to stabilize it against the proximal surface, whereas the cutting edge engages the calculus without nicking the tooth. The instrument is activated with a push motion while the side of the blade is held firmly against the root.
The Quétin furcation curettes are actually hoes with a shallow, half-moon radius that fits into the roof or floor of the furcation. The curvature of the tip also fits into developmental depressions on the inner aspects of the roots. The shanks are slightly curved for better access, and the tips are available in two widths (Figure 46-40). The BL1 (buccal-lingual) and MD1 (mesial-distal) instruments are small and fine, with a 0.9-mm blade width. The BL2 and MD2 instruments are larger and wider, with a 1.3-mm blade width.
These instruments remove burnished calculus from recessed areas of the furcation where curettes, even the mini-bladed curettes, are often too large to gain access. Using mini-bladed Gracey curettes and Gracey Curvettes in the roof or floor of the furcation may unintentionally create gouges and grooves. The Quétin instruments, however, are well suited for this area and lessen the likelihood of root damage.
Diamond-coated files are unique instruments used for final finishing of root surfaces. These files do not have cutting edges; instead, they are coated with very-fine-grit diamond (Figure 46-41). The most useful diamond files are the buccal-lingual instruments, which are used in furcations and also adapt well to many other root surfaces.
New diamond files are sharply abrasive and should be used with light, even pressure against the root surface to avoid gouging or grooving. When viewing the root surface with the dental endoscope after all tactilely detectable deposits are gone, small embedded remnants of calculus in the root surface can be observed. Diamond files are used similar to an emery board to remove these minute remnants of calculus from the root, creating a surface that is free of all visible accretions. Diamond files can produce a smooth, even, clean, and highly polished root surface.
Diamond files must be used carefully because they can cause overinstrumentation of the root surface. They will remove too much root structure if they are used with excessive force, are poorly adapted to root morphology, or used too long in one place.
A dental endoscope has been introduced for use subgingivally in the diagnosis and treatment of periodontal disease (Figure 46-42). The Perioscopy system (Perioscopy, Inc., Oakland, CA) consists of a 0.99-mm-diameter, reusable fiberoptic endoscope over which is fitted a disposable, sterile sheath. The fiberoptic endoscope fits onto periodontal probes and ultrasonic instruments that have been designed to accept it (Figure 46-43). The sheath delivers water irrigation that flushes the pocket while the endoscope is being used, keeping the field clear. The fiberoptic endoscope attaches to a medical-grade charged-coupled device (CCD) video camera and light source that produces an image on a flat-panel monitor for viewing during subgingival exploration and instrumentation. This device allows clear visualization deeply into subgingival pockets and furcations (Figure 46-44). It permits operators to detect the presence and location of subgingival deposits and guides them in the thorough removal of these deposits. Magnification ranges from 24 to 48 times, enabling visualization of even minute deposits of plaque and calculus. Using this device, operators can achieve levels of root debridement and cleanliness that are much more difficult or impossible to produce without it.149,150,167,168 The Perioscopy system can also be used to evaluate subgingival areas for caries, defective restorations, root fractures, and resorption.
Rubber cups consist of a rubber shell with or without webbed configurations in the hollow interior (Figure 46-45). They are used in the handpiece with a special prophylaxis angle. The handpiece, prophylaxis angle, and rubber cup must be sterilized after each patient use, or a disposable plastic prophylaxis angle and rubber cup may be used and then discarded (Figure 46-46). A good cleansing and polishing paste that contains fluoride should be used and kept moist to minimize frictional heat as the cup revolves. Polishing pastes are available in fine, medium, or coarse grits and are packaged in small, convenient, single-use containers. Aggressive use of the rubber cup with any abrasive may remove the layer of cementum, which is thin in the cervical area.
Dental tape with polishing paste is used for polishing proximal surfaces that are inaccessible to other polishing instruments. The tape is passed interproximally while being kept at a right angle to the long axis of the tooth and is activated with a firm labiolingual motion. Particular care is taken to avoid injury to the gingiva. The area should be cleansed with warm water to remove all remnants of paste.
The first specially designed handpiece to deliver an air-powered slurry of warm water and sodium bicarbonate for polishing was introduced in the early 1980s. This device, called the Prophy-Jet (Dentsply International, York, PA) is very effective for the removal of extrinsic stains and soft deposits (Figure 46-47). The slurry removes stains rapidly and efficiently by mechanical abrasion and provides warm water for rinsing and lavage. The flow rate of abrasive cleansing power can be adjusted to increase the amount of powder for heavier stain removal. Currently, many manufacturers produce air-powder polishing systems that use various powder formulas.
The results of studies on the abrasive effect of the air-powder polishing devices using sodium bicarbonate and aluminum trihydroxide on cementum and dentin show that significant tooth substance can be lost.2,19,110,118 Damage to gingival tissue is transient and insignificant clinically, but amalgam restorations, composite resins, cements, and other nonmetallic materials can be roughened.13,43,67,89,161 Polishing powders containing glycine rather than sodium bicarbonate recently have been introduced for subgingival biofilm removal from root surfaces.97,117 Air-powder polishing can be used safely on titanium implant surfaces.74,91,126
Patients with medical histories of respiratory illnesses and hemodialysis are not candidates for the use of the air-powder polishing device.145,165 Powders containing sodium bicarbonate should not be used on patients with histories of hypertension, sodium-restricted diets, or medications affecting the electrolyte balance.125 Patients with infectious diseases should not be treated with this device because of the large quantity of aerosol created. A preprocedural rinse with 0.12% chlorhexidine gluconate should be used to minimize the microbial content of the aerosol.17 High-speed evacuation should also be used to eliminate as much of the aerosol as possible.57
Effective instrumentation is governed by a number of general principles that are common to all periodontal instruments. Proper position of the patient and the operator, illumination and retraction for optimal visibility, and sharp instruments are fundamental prerequisites. A constant awareness of tooth and root morphologic features and of the condition of the periodontal tissues is also essential. Knowledge of instrument design enables the clinician to select the proper instrument for the procedure and the correct area in which it will be performed. In addition to these principles, the basic concepts of grasp, finger rest, adaptation, angulation, and stroke must be understood before clinical instrument-handling skills can be mastered.
Accessibility facilitates thoroughness of instrumentation. The position of the patient and operator should provide maximal accessibility to the area of operation. Inadequate accessibility impedes thorough instrumentation, prematurely tires the operator, and diminishes his or her effectiveness.
The clinician should be seated on a comfortable operating stool that has been positioned so that the clinician’s feet are flat on the floor with the thighs parallel to the floor. The clinician should be able to observe the field of operation while keeping the back straight and the head erect.
The patient should be in a supine position and placed so that the mouth is close to the resting elbow of the clinician. For instrumentation of the maxillary arch, the patient should be asked to raise the chin slightly to provide optimal visibility and accessibility. For instrumentation on the mandibular arch, it may be necessary to raise the back of the chair slightly and request that the patient lower the chin until the mandible is parallel to the floor. This will especially facilitate work on the lingual surfaces of the mandibular anterior teeth.
Whenever possible, direct vision with direct illumination from the dental light is most desirable (Figure 46-48). If this is not possible, indirect vision may be obtained by using the mouth mirror (Figure 46-49) and indirect illumination may be obtained by using the mirror to reflect light to where it is needed (Figure 46-50). Indirect vision and indirect illumination are often used simultaneously (Figure 46-51).
Retraction provides visibility, accessibility, and illumination. Depending on the location of the area of operation, the fingers and/or the mirror are used for retraction. The mirror may be used for retraction of the cheeks or the tongue; the index finger is used for retraction of the lips or cheeks. The following methods are effective for retraction:
When retracting, care should be taken to avoid irritation to the angles of the mouth. If the lips and skin are dry, softening the lips with petroleum jelly before instrumentation is a helpful precaution against cracking and bleeding. Careful retraction is especially important for patients with a history of recurrent herpes labialis because these patients may easily develop herpetic lesions after instrumentation.
Before any instrumentation, all instruments should be inspected to make sure that they are clean, sterile, and in good condition. The working ends of pointed or bladed instruments must be sharp to be effective. Sharp instruments enhance tactile sensitivity and allow the clinician to work more precisely and efficiently (see later discussion). Dull instruments may lead to incomplete calculus removal and unnecessary trauma because of the excess force usually applied to compensate for their ineffectiveness.
Despite good visibility, illumination, and retraction, instrumentation can be hampered if the operative field is obscured by saliva, blood, and debris. The pooling of saliva interferes with visibility during instrumentation and impedes control because a firm finger rest cannot be established on wet, slippery tooth surfaces. Adequate suction is essential and can be achieved with a saliva ejector or, if working with an assistant, an aspirator.
Gingival bleeding is an unavoidable consequence of subgingival instrumentation. In areas of inflammation, bleeding is not necessarily an indication of trauma from incorrect technique but rather may indicate ulceration of the pocket epithelium. Blood and debris can be removed from the operative field with suction and by wiping or blotting with gauze squares. The operative field should also be flushed occasionally with water.
Compressed air and gauze squares can be used to facilitate visual inspection of tooth surfaces just below the gingival margin during instrumentation. A jet of air directed into the pocket deflects a retractable gingival margin. Retractable tissue can also be deflected away from the tooth by gently packing the edge of a gauze square into the pocket with the back of a curette. Immediately after the gauze is removed, the subgingival area should be clean, dry, and clearly visible for a brief interval.
Stability of the instrument and the hand is the primary requisite for controlled instrumentation. Stability and control are essential for effective instrumentation and avoidance of injury to the patient or clinician. The two factors of major importance in providing stability are the instrument grasp and the finger rest.
A proper grasp is essential for precise control of movements made during periodontal instrumentation. The most effective and stable grasp for all periodontal instruments is the modified pen grasp (Figure 46-55). Although other grasps are possible, this modification of the standard pen grasp (Figure 46-56) ensures the greatest control in performing intraoral procedures.
The thumb, index finger, and middle finger are used to hold the instrument as a pen is held, but the middle finger is positioned so that the side of the pad next to the fingernail is resting on the instrument shank. The index finger is bent at the second joint from the fingertip and is positioned well above the middle finger on the same side of the handle.
The pad of the thumb is placed midway between the middle and index fingers on the opposite side of the handle. This creates a triangle of forces, or tripod effect, that enhances control because it counteracts the tendency of the instrument to turn uncontrollably between the fingers when scaling force is applied to the tooth. This stable modified pen grasp enhances control because it enables the clinician to roll the instrument in precise degrees with the thumb against the index and middle fingers to adapt the blade to the slightest changes in tooth contour. The modified pen grasp also enhances tactile sensitivity because slight irregularities on the tooth surface are best perceived when the tactile-sensitive pad of the middle finger is placed on the shank of the instrument.
The palm and thumb grasp (Figure 46-57) is useful for stabilizing instruments during sharpening and for manipulating air and water syringes, but it is not recommended for periodontal instrumentation. Maneuverability and tactile sensitivity are so inhibited by this grasp that it is unsuitable for the precise, controlled movements necessary during periodontal procedures.
The finger rest serves to stabilize the hand and the instrument by providing a firm fulcrum as movements are made to activate the instrument. A good finger rest prevents injury and laceration of the gingiva and surrounding tissues by poorly controlled instruments. The fourth (ring) finger is preferred by most clinicians for the finger rest. Although it is possible to use the third (middle) finger for the finger rest, this is not recommended because it restricts the arc of movement during the activation of strokes and severely curtails the use of the middle finger for both control and tactile sensitivity. Maximal control is achieved when the middle finger is kept between the instrument shank and the fourth finger. This “built-up” fulcrum is an integral part of the wrist-forearm action that activates the powerful working stroke for calculus removal. Whenever possible, these two fingers should be kept together to work as a one-unit fulcrum during scaling and root planing. Separation of the middle and fourth fingers during scaling strokes results in a loss of power and control because it forces the clinician to rely solely on finger flexing for activation of the instrument.
Finger rests may be generally classified as intraoral finger rests or extraoral fulcrums. Intraoral finger rests on tooth surfaces ideally are established close to the working area. Variations of intraoral finger rests and extraoral fulcrums are used whenever good angulation and a sufficient arc of movement cannot be achieved by a finger rest close to the working area. The following examples illustrate the different variations of the intraoral finger rest:
Extraoral fulcrums are essential for effective instrumentation of some aspects of the maxillary posterior teeth. When properly established, they allow optimal access and angulation while providing adequate stabilization. Extraoral fulcrums are not “finger rests” in the literal sense because the tips or pads of the fingers are not used for extraoral fulcrums as they are for intraoral finger rests. Instead, as much of the front or back surface of the fingers as possible is placed on the patient’s face to provide the greatest degree of stability. The two most common extraoral fulcrums are used as follows:
1. Palm up: The palm-up fulcrum is established by resting the backs of the middle and fourth fingers on the skin overlying the lateral aspect of the mandible on the right side of the face (Figure 46-62).
2. Palm down: The palm-down fulcrum is established by resting the front surfaces of the middle and fourth fingers on the skin overlying the lateral aspect of the mandible on the left side of the face (Figure 46-63).
Both intraoral finger rests and extraoral fulcrums may be reinforced by applying the index finger or thumb of the nonoperating hand to the handle or shank of the instrument for added control and pressure against the tooth. The reinforcing finger is usually employed for opposite-arch or extraoral fulcrums when precise control and pressure are compromised by the longer distance between the fulcrum and the working end of the instrument. Figure 46-64 shows the index finger–reinforced rest, and Figure 46-65 shows the thumb-reinforced rest.
Adaptation refers to the manner in which the working end of a periodontal instrument is placed against the surface of a tooth. The objective of adaptation is to make the working end of the instrument conform to the contour of the tooth surface. Precise adaptation must be maintained with all instruments to avoid trauma to the soft tissues and root surfaces and to ensure maximum effectiveness of instrumentation.
Correct adaptation of the probe is quite simple. The tip and side of the probe should be flush against the tooth surface as vertical strokes are activated within the crevice. Bladed instruments (e.g., curettes) and sharp-pointed instruments (e.g., explorers) are more difficult to adapt. The ends of these instruments are sharp and can lacerate tissue, so adaptation in subgingival areas becomes especially important. The lower third of the working end, which is the last few millimeters adjacent to the toe or tip, must be kept in constant contact with the tooth while it is moving over varying tooth contours (Figure 46-66). Precise adaptation is maintained by carefully rolling the handle of the instrument against the index and middle fingers with the thumb. This rotates the instrument in slight degrees so that the toe or tip leads into concavities and around convexities. On convex surfaces such as line angles, it is not possible to adapt more than 1 or 2 mm of the working end against the tooth. Even on what appear to be broader, flatter surfaces, no more than 1 or 2 mm of the working end can be adapted because the tooth surface, although it may seem flat, is actually slightly curved.
If only the middle third of the working end is adapted on a convex surface so that the blade contacts the tooth at a tangent, the toe or sharp tip will jut out into soft tissue, causing trauma and discomfort (Figure 46-67).
If the instrument is adapted so that only the toe or tip is in contact, the soft tissue can be distended or compressed by the back of the working end, also causing trauma and discomfort. A curette that is improperly adapted in this manner can be particularly damaging because the toe can gouge or groove the root surface.
Correct angulation is essential for effective calculus removal. For subgingival insertion of a bladed instrument such as a curette, angulation should be as close to 0 degree as possible (Figure 46-68, A). The end of the instrument can be inserted to the base of the pocket more easily with the face of the blade flush against the tooth. During scaling and root planing, optimal angulation is between 45 and 90 degrees (Figure 46-68, B). The exact blade angulation depends on the amount and nature of the calculus, the procedure being performed, and the condition of the tissue. Blade angulation is diminished or closed by tilting the lower shank of the instrument toward the tooth. It is increased or opened by tilting the lower shank away from the tooth. During scaling strokes on heavy, tenacious calculus, angulation should be just less than 90 degrees so that the cutting edge “bites” into the calculus. With angulation of less than 45 degrees, the cutting edge will not bite into or engage the calculus properly (Figure 46-68, C). Instead, it will slide over the calculus, smoothing or “burnishing” it. If angulation is more than 90 degrees, the lateral surface of the blade, rather than the cutting edge, will be against the tooth, and the calculus will not be removed and may become burnished (Figure 46-68, D). After the calculus has been removed, angulation of just less than 90 degrees may be maintained, or the angle may be slightly closed as the root surface is smoothed with light, root-planing strokes.
Lateral pressure refers to the pressure created when force is applied against the surface of a tooth with the cutting edge of a bladed instrument. The exact amount of pressure applied must be varied according to the nature of the calculus and according to whether the stroke is intended for initial scaling to remove calculus or for root planing to smooth the root surface.
Lateral pressure may be firm, moderate, or light. When removing calculus, lateral pressure is initially applied firmly or moderately and is progressively diminished until light lateral pressure is applied for the final root-planing strokes. When insufficient lateral pressure is applied for the removal of heavy calculus, rough ledges or lumps may be shaved to thin, smooth sheets of burnished calculus that are difficult to detect and remove. This burnishing effect often occurs in areas of developmental depressions and along the cementoenamel junction.
Although firm lateral pressure is necessary for the thorough removal of calculus, indiscriminate, unwarranted, or uncontrolled application of heavy forces during instrumentation should be avoided. Repeated application of excessively heavy strokes often nicks or gouges the root surface.
The careful application of varied and controlled amounts of lateral pressure during instrumentation is an integral part of effective scaling and root-planing techniques and is critical to the success of both these procedures.
Three basic types of strokes are used during instrumentation: the exploratory stroke, the scaling stroke, and the root-planing stroke. Any of these basic strokes may be activated by a pull or a push motion in a vertical, oblique, or horizontal direction (Figure 46-69). Vertical and oblique strokes are used most frequently. Horizontal strokes are used selectively on line angles or deep pockets that cannot be negotiated with vertical or oblique strokes. The direction, length, pressure, and number of strokes necessary for either scaling or root planing are determined by four major factors: (1) gingival position and tone, (2) pocket depth and shape, (3) tooth contour, and (4) the amount and nature of the calculus or roughness.