Principles of instrumentation

The accurate use of periodontal instruments is fundamental for appropriate periodontal treatment. The outcome of periodontal therapy to a great extent depends on the operator’s skill to use the periodontal instruments in an accurate manner, following the principles of instrumentation. With clinical experience, the principles of periodontal instrumentation can be mastered. In the following sections, various aspects of periodontal instrumentation shall be discussed.

Principles of instrumentation

The basic principles of periodontal instrumentation are 1,

  1. Accessibility (operator’s posture and patient positioning)
  2. Visibility, illumination, and retraction
  3. Selection of proper instrument
  4. Condition of instruments (sharpness)
  5. Maintaining a clean field
  6. Instrument stabilization
  7. Instrument activation

Accessibility (operator’s posture and patient positioning)

The clinician’s position relative to the patient should provide complete accessibility to the area of operation.  First of all, the clinician must be seated comfortably on the operating stool. A correct position of the operator is very important to help the operator to have good visibility and accessibility of the oral cavity. Improper positioning of chair height will cause premature tiring of the operator and also adversely affect the quality of instrumentation 2, 3. For the ease of understanding, the patient’s face is assumed as a clock with patient’s chin having 6 o’clock position. The right-handed clinician sits between 9 and 12 o’clock whereas the left-handed clinician sits on the opposite side, from 12 to 3 o’clock position (Figure 50.1).

Figure 50.1 Operator’ s chair side positions around the dental chair

Operator’ s chair side positions around the dental chair

Operator’s posture during dental treatment:

The operator should be in optimum comfort during operating to adequately perform instrumentation (Figure 50.2).

Figure 50.2 Operator’ s posture while working on the patient

Operator’ s posture while working on the patient

  • The seat height of the dental stool should be low enough so that the heels of the operator touch the floor. The angle between lower and upper legs at knee joint of about 110° or a little more, with the legs, slightly spread.
  • The operator should sit in a relaxed, symmetrical posture upright with the arms against the upper body which minimizes the static load of upper arms and shoulders. While operating, the operator should minimize the……………………………

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  • The operator (right handed), when working at 9.00 to 12.00 o’clock position should spread the feet apart so that the legs and the dental stool make a tripod, creating a stable position for the operator. The same position should be achieved for a left-handed operator at 12.00 to 3.00 o’clock position.
  • For operating the maxillary teeth, patient’s chair height should be 8 cm or 3 inches below the shoulder level of the operator. While operating on mandibular teeth, the patient chair height should be 16 cm or 6 inches below the level of operator’s……………

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  • While working, the distance between working field in the mouth and eyes or spectacles normally ranges between 35-40 cm.
  • The back of the operator should be supported at the upper/back side of the pelvis. It helps in maintaining the upright position when muscles in the pelvic region become too fatigued to maintain an upright position of the back 4.
 

Know more…………

Operating zones for dental team 5:

Operator’s zone:

The operator’s zone is the working area of the clinician or operator to have access to all areas of the patient’s oral cavity. For the right-handed operator, the operating zone is 8 to 12 o’clock whereas for a left-handed patient it is 12 to 4 o’clock.

Dental assistant’s zone:

This is the area where dental assistant assists the operator. For the right-handed operator, the dental assistant’s zone is 2 to 4 o’clock and for the left-handed operator, it is 8 to 10 o’clock 6.

Transfer zone:

This is the area where the operator and dental assistant exchange instruments and materials for delivery to or from the oral cavity during the treatment. The transfer zone is 4 to 8 o’clock.

Static zone:

The 12 to 2 o’clock (for the right-handed operator) and 10 to 12 o’clock (for the left-handed operator) positions are referred to as static positions which are in the non-active zone. Equipment such as the instrument cart or mobile cabinet can be placed in this zone.

Operator’s positions around dental chair while operating:

An appropriate positioning of the operator while working on different parts of the dentition is necessary to efficiently perform the instrumentation 7. The operator positions around the patient based on the operator’s working hand may be the following,

Right handed operator or clinician:

  • 7 o’clock position- to the front of the patient’s head.
  • 9 o’clock position- to the side of the patient’s head.
  • 10 to 11 o’clock position- to the back of the patient’s head.
  • 12 o’clock position- directly behind the patient’s head.

Left handed operator or clinician:

  • 5 o’clock position- to the front of the patient’s head.
  • 3 o’clock position- to the side of the patient’s head
  • 2 to 10 o’clock position- to the back of the patient’s head.
  • 12 o’clock position- directly behind the patient’s head.

While working on different parts of maxillary and mandibular arches, the operator position varies according to the teeth to be operated and tooth surfaces to be operated. For the ease of understanding, the maxillary and mandibular arches have been divided into six sextants (Figure 50.3 a, b). The facial and lingual/palatal surfaces of posterior teeth and mesial and distal surfaces in the sextant 2 and 5 have been shown with different colors (Figure 50.4 a, b).

Figure 50.3 a, b The maxillary and mandibular arches have been divided into six sextants and color coding has been done for the ease of understanding of operator’ s position during instrumentation.

Operator’ s  position  during  instrumentation

Positioning for sextants 1 and 3:

Right handed operator:

To operate on the facial surfaces of sextant 1 (blue) and palatal surfaces of sextant 3 (blue), the clinician sits in the region from 9 to 12 o’clock. The patient’s head is turned away from the clinician with the head tilted upward. To work on the palatal surfaces of sextant 1 (yellow) and the facial surfaces of sextant 3 (yellow), clinician sits in 10 to 12 o’clock region. The patient’s head is turned toward the clinician with the chin tilted upward.

Left handed operator:

For a left-handed clinician, to operate on the facial surfaces of teeth in sextant 1 (blue) and palatal surfaces of sextant 3 (blue), the clinician sits in the region of 3 to 12 o’clock. The head of the patient is tilted towards the clinician with chin tilted upwards. To operate on the palatal surfaces of sextant 1 (yellow) and facial surfaces of sextant 3 (yellow), the clinician sits in 2-12 o’clock region with the patient’s head tilted away from the clinician and chin tilted upwards.

Figure 50.4 The maxillary (a) and mandibular (b) anterior teeth have been color coded and divided into two halves for the ease of understanding of the operator’ s position during instrumentation

Operator’ s  position  during  instrumentation

Positioning for sextant 2:

Right handed operator:

The lingual and labial surfaces of the maxillary teeth in the second sextant can be divided into two portions at the midline. For a right-handed operator, the blue portions are toward the clinician and yellow portions are away from the clinician during treatment. To operate on the blue surfaces (towards the operator), the patient’s head should be……………………

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Left handed operator:

To operate on the yellow (towards the clinician) surfaces, the operator sits in 1-3 o’clock region with the head of the patient turned away from the clinician and the chin tilted upwards. To operate on blue surfaces (away from the operator) surfaces, the operator sits in 1-12 o’clock region with the head of the patient tilted towards the clinician and chin tilted upwards

Positioning for sextant 5:

Right handed operator:

Similar to the sextant 2, the facial and lingual surfaces of mandibular teeth are divided into two halves at midline. To operate on the surfaces towards the operator (blue), the patient’s head is turned…………………

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Left handed operator:

To operate on yellow surfaces (towards the clinician), the operator sits in 2-12 o’clock region with the patient’s head turned away from the operator and the chin tilted down. To operate on the blue surfaces (away from the patient), the operator sits in 12-1 o’clock region with the patient’s head is tilted towards to operator and chin is tilted down.

Positioning for sextants 4 and 6:

Right handed operator:

To operate on the facial surfaces in sextant 4 (blue) and the lingual surfaces in sextant 6 (blue), head of the patient is turned toward the operator with the chin tilted down. The operator’s position is 9 to 11 o’clock region. To operate on the lingual surfaces in sextant 4 (yellow) and the facial surfaces in sextant 6 (yellow), the patient’s head is tilted away from the operator and the chin is tilted upwards. The operator sits in 9 to 10 o’clock position.

Left handed operator:

To operate on the facial surfaces of sextant 4 (blue) and lingual surfaces of sextant 6 (blue), the operator sits in 1-3 o’clock region with the patient’s head is tilted away from the operator and the chin is tilted downwards. To operate on the lingual surfaces of sextant 4 (yellow) and facial surfaces of sextant 6 (yellow), the operator sits in 2-3 o’clock region with the head of the patient is turned toward the operator with the chin tilted downwards.

Patient’s position during dental treatment:

The common patient positions during dental treatment are,

  • Supine position
  • Reclined position
  • Upright position

The most common patient position during periodontal treatment is the……………….

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Know more…………..

Instrument delivery during the treatment 8:

There are primarily three methods adopted by dentists for the instrument and material delivery to and from the oral cavity. These are,

  • Over the patient instrument delivery
  • Side instrument delivery
  • Rare instrument delivery

Over the patient instrument delivery:

Over the patient instrument delivery is used by the majority of clinicians. In this instrument delivery system, the dental unit is mounted with an arm system which brings the chair controls near the operator. The exchange of the instruments and dental material between the dentist and dental assistant takes place across the patient’s chest (trans thorax delivery).

Advantages:

  • All the instruments and materials are in close proximity to the dentist or dental assistant, facilitating minimum movement of the operator during the treatment.
  • Minimizes operatory floor space utilization.
  • Minimizes eye fatigue because the operator does not need to adjust the eyes in the oral cavity from distantly placed instruments.

Disadvantages:

  • While transferring the dental material, it may slip and fall on the patient, which is a source of embarrassment to the operator. So, both the dentist and dental assistant should be very careful while transferring the instruments and dental materials over the patient.
  • It reduces dental assistant’s access to chair controls.

Side instrument delivery:

The side instrument delivery system has been specifically designed for four-handed sit-down dentistry. Here, instrument tray is placed on a cabinet or cart in close proximity to the dentist. The instrument placement and transfer in this delivery system is outside the normal center of vision of the patient.

Advantages:

  • Allows good vision of the oral cavity both to the operator and dental assistant.
  • Allows flexible seating and instrument location.
  • Instruments are out of the patient’s view which may help in reducing patient anxiety.
  • Allows more mobility of the operator and chairside assistant around the dental chair due to the mobile instrument cart or cabinet.

Disadvantages:

  • Requires more operatory floor space.
  • Access of dental assistant to operator’s instruments is reduced.

Rare instrument delivery:

In this delivery system, instruments are placed behind the dental chair on a cart or cabinet. Here, instruments are always behind the patient and are usually out of his/her view. This is the most effective instrument delivery system for sit down four-handed dentistry.

Advantages:

  • Excellent access to instruments, both by the dentist and the dental assistant.
  • Instruments are out of the patient’s view.
  • Requires minimal operatory floor space.
  • Allows flexibility for changing positions by the operator and the dental assistant while treating the patient.

Disadvantages:

  • Its use is primarily limited to sit down dentistry.

 

Visibility, illumination, and retraction

The second principle of periodontal instrumentation is good visibility, illumination, and retraction. The operator should preferably operate on the patient with direct vision and direct illumination. If working under direct vision is not possible, indirect vision may be obtained by using mouth mirror for reflecting light to the site to be operated. The light beam of the dental chair lamp should be oriented parallel to the viewing direction in order to obtain shadow free lighting. It minimizes shadows from the hands, teeth, lips and cheek on and around the working field. To achieve this, the dental light should have three axis of adjustment (orthogonal), allowing the lamp to turn in all directions.

Retraction of cheeks, lips or tongue provides the operator a good accessibility to different areas in dentition. Mouth mirror is used to retract cheeks and tongue and index figure may be used to retract the lips or cheeks. While retracting cheek with mouth mirror, the index figure of the non-operating hand should be used to retract the lips and protect the angle of the mouth. The angle of mouth should be protected while using a mouth mirror. If the skin and lips are dry, petroleum jelly should be used to moisten them. It is especially important in cases with recurrent herpes labialis because the patient may develop herpetic lesions following instrumentation.

Selection of proper instrument

It is important to select appropriate instruments for periodontal non-surgical or surgical procedures. For example, scalers are used for supra-gingival calculus removal whereas curettes are used for subgingival calculus removal due to their relatively small working end which can be inserted below the gingival margin. The clinician must choose the best instruments out of those made by various manufacturers, considering their blade quality (size and shape), shank quality (rigid or flexible) and handle quality (solid or hollow). Factors which determine the selection of an instrument include quality and quantity of calculus, severity of periodontal involvement, gingival retractability, root morphology and overall accessibility 9 (Table 50.1)The Gracey curettes have been given numbers so that they can be easily identified for use in various parts of the dentition. The most significant property of an instrument is its blade size. In areas with narrow pockets, narrow blade size is used. Second important property of an instrument is the flexibility or rigidity of the shank. Rigid shank instruments are suitable for tenacious calculus removal whereas flexible shank instruments use suitable for root planing.

The tooth surface on which instrumentation has to be done is another important factor, determining the selection of instruments. Tooth surface associated factors which determine the instrument selection include tooth location within the oral cavity (anterior/posterior/maxillary/mandibular), specific site on the tooth (mesial/distal/buccal/labial/lingual/palatal/line angle areas), the morphology of tooth (anatomy of cementoenamel junction/furcation) and location of the deposit (supra or subgingival). Also, tooth alignment in the dental arch (crowding/spacing), root proximity and missing teeth also affect the instrument selection. Considering all these factors universal or area specific, regular shank or long shank, regular blade or small blade curettes are chosen.

Lastly, the individual choice of the clinician for a particular instrument with which he/she can work comfortably and achieve desired results is considered.

Table 50.1 Factors determining the selection of instruments

[table “131” not found /]

Condition of instruments (sharpness)

The instruments used by the operator should be adequately sharp and clean. Use of the dull instruments results in inadequate instrumentation which may become an important reason for the failure of the treatment. The sharp instruments increase the tactile sensation as well as facilitate good debridement, helping in achieving favorable outcomes of periodontal treatment. Sharp instruments can be used more precisely and efficiently as compared to dull instruments 10.

Maintaining a clean field

The operating field should be free from saliva, blood, and debris. In spite of good illumination and retraction, accumulation of…………………

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Instrument stabilization

The appropriate stabilization of the instrument is the basic requirement of proper instrumentation. The stabilization and control over the instrument are essential for effective instrumentation. The instrument grasp and the finger rest are two major factors determining the stabilization of the instrument.

Instrument grasp:

A proper instrument grasp facilitates adequate tactile sensation, adaptation, activation and comfort to the operator 11. An appropriate instrument grasp minimizes operator fatigue, thus facilitating good instrumentation. The commonly used grasps to hold periodontal instruments include standard pen grasp, modified pen grasp and palm and thumb grasp 12. Out of these, the most effective and stable grasp for all periodontal instruments is the modified pen grasp 13.

Standard pen grasp:

In this grasp, the index finger and thumb Index finger and thumb hold the instrument with side of the middle finger resting on the shank (Figure 50.5). This grasp provides less tactile sensitivity and flexibility of movement during instrumentation as compared to the modified pen grasp. Hence, this grasp has a limited use during instrumentation.

Figure 50.5 Standard pen grasp

Standard pen grasp

Modified pen grasp:

It is the modification of standard pen grasp. In this grasp, the clinician holds the instrument with the pads of the index finger and the thumb opposite to each other on the handle closer to the working end. The thumb and index finger are not touching, thereby creating a tripod effect with the middle finger placed along the shank of the instrument. The tripod effect provides stability to the grasp and facilitates ease of instrument control (Figure 50.6). The forefinger and thumb make a “V” shape during instrument activation in this grasp. While holding the instrument in this grasp, the index finger is kept…………………………..

123The middle and ring finger should always remain in contact somewhere along the length of either finger, facilitating proper wrist motion during instrument activation.

Figure 50.6 Modified pen grasp

Modified pen grasp

Palm and thumb grasp:

This grasp is primarily used while sharpening of the instruments and during manipulation of air and water syringes. This grasp is not recommended for periodontal instrumentation. The tactile sensitivity and control over the instrument are limited with this grasp which is a prime requirement during periodontal instrumentation (Figure 50.7).

Figure 50.7 Palm and thumb grasp

Palm and thumb grasp

Finger rest (fulcrum):

Finger rest serves as a stabilization point for the instrument. It helps the hand and instrument to be moved as a single unit. The lateral surface of the pad of the ring finger of the working hand is most commonly used as the fulcrum. Middle finger may also be used as fulcrum but it is not recommended as it restricts the arc of movement during instrument activation. It also hampers the instrument control and tactile sensitivity. The activation of the instrument is done by exerting downward pressure on the fulcrum finger along with applying pressure on the instrument with the index finger and thumb to increase stability and control during instrumentation. While using fulcrum, maximum control is achieved by placing the ring finger close to the middle finger. These two fingers function as a unit during scaling and root planing.

Finger rests can be classified as intraoral or extra-oral. The intraoral finger rests can be conventional, cross arch, opposite arch or finger on finger. The most commonly used intraoral finger rest is conventional finger rest. Following is the description of the various intraoral finger rests,

  • Conventional rest: Here, finger rest is established on the tooth surface immediately adjacent to the working area (Figure 50.8).
  • Cross-arch rest: In this case, finger rest is established on the tooth surface on the other side of the same arch (Figure 50.9).
  • Opposite arch: Finger rest is established on the tooth surfaces on the opposite arch, for example, while working on the maxillary arch, finger rest is established on the mandibular arch (Figure 50.10).
  • Finger on finger rest: It is established on the thumb or index finger of the non-operating hand (Figure 50.11).

Figure 50.8 Conventional finger rest

Conventional finger rest

Figure 50.9 Cross-arch finger rest

Cross-arch finger rest

Figure 50.10 Opposite arch finger rest

Opposite arch finger rest.

Figure 50.1 1 Finger on finger rest

Finger on finger rest.

Extra- oral fulcrums are sometimes used to achieve instrument stability while doing instrumentation on certain surfaces of posterior maxillary teeth. Extra- oral fulcrums are not exactly “finger rests” because tip or the pad of fingers is not used as a fulcrum, instead, front or back surfaces of the fingers are placed on the patient’s face to achieve appropriate stability. The most important factors affecting extraoral fulcrum include the surface area of contact between the hand and the patient’s face, adequate pressure, and extended grasp. The surface area of contact between the hand and patient’s face should be maximized to establish a firm foundation. Adequate pressure from the part of hand in contact with the face ensures good control over the scaling or root planing strokes. It must be noted that it is bone and soft tissue of the patient’s face that serve as the fulcrum to stabilize the working stroke. The amount of pressure applied depends on the type of stroke. For exploratory strokes, only a light hand pressure is applied, whereas for heavy calculus removal, firm-pressured hand rest is required. For debridement strokes, moderate-pressured hand rest is required. Extra-oral fulcrums use extended grasps. If the instrument is grasped too close to the working end fingers of the clinician may impinge on the lips of the patient, which may result in pain to the patient and instability for the clinician. The extraoral fulcrums may be palm up or palm down.

Palm-up fulcrum:

In this fulcrum, the backsides of middle, ring and little fingers are placed straight and together firmly against the skin overlying the lateral aspect of the mandible on the face (Figure 50.12). For right-handed operator, it is used on the right side of the face. Strokes are activated by pulling in a coronal direction with the arm, not by flexing the fingers. The stroke movement is initiated at the shoulder joint and fingers remain stationary in their grasp position as the arm activates the working stroke. To achieve maximum control over the instrument stroke, as much as possible back surfaces of the fingers should be in firm contact with the basal portion of the mandible.

Figure 50.12 Palm-up fulcrum

Palm-up fulcrum

Palm-down fulcrum:

In this fulcrum, the front surfaces of the fingers are placed flatly against the skin overlying the lateral aspect of the mandible (Figure 50.13). For the right-handed operator, it is used on the left side of the face. The palm of the hand should closely cup the mandible to provide additional support whenever possible.

Figure 50.13 Palm down fulcrum

Palm down fulcrum

Reinforced rests:

Reinforced rest can provide extra stability to the extraoral fulcrum. It is established by placing finger or thumb of the non-operating hand to the handle or shank of the instrument during applying working strokes (Figure 50.14 a, b). This type of rest is commonly used when the distance between the fulcrum and the curette blade is more and a precise control and pressure are compromised by this distance. The reinforcing finger acts as a support that provides added control and pressure against the tooth. This type of rest can only be used when the area to be operated is in direct vision of the operator because the non-functioning hand cannot be used to hold the mouth mirror.

Figure 50.14 (a) Thumb re-inforced rest

Thumb re-inforced rest

Figure 50.14 (b) Finger re-inforced rest

Finger re-inforced rest

Instrument activation

The instrument is activated by appropriately adapting it on the tooth/root surface, achieving appropriate angulation of the cutting edge, applying adequate pressure before initiating the stroke and lastly making the desired stroke.

Instrument insertion:

The instrument is inserted into the gingival sulcus or pocket with its blade to tooth angle as close to 0⁰ as possible. This angulation is easy to achieve with instruments like a file that adapts parallel to the calculus deposit. To achieve this angulation with curettes or sickle, the blade of the instrument is completely closed against the tooth surface. To achieve this, the clinician has to…………………………….

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It must be noted that if clinician places the blade of the instrument at the apical edge of calculus and not below the deposit, the apical border of calculus will remain on the root surface after the working stroke is applied.

Some instruments such as explorers and probes are inserted as well as activated in close to 0⁰ angulations. The angulation is increased only when the tip or the terminal end of the instrument is made to touch the tooth surface.

Instrument adaptation:

The adaptation of the instrument depends on the type of procedure to be performed and type of instrument to be used. In general, the instrument is adapted by placing lower 1/3rd to 2/3rd of the blade against the tooth surface. The working end of the instrument is placed on the tooth surface in such a way that it precisely adapts to the contour of the tooth/root surface. The simplest instrument to adapt is a periodontal probe. It is simply placed along the tooth surface with at least two points in contact with the tooth surface along its length. Vertical strokes are given to activate the instrument. Sharp instruments such as curettes and pointed instruments such as explorers are more difficult to adapt because they can injure the soft tissue easily. The lower 1/3rd of these instruments should be kept in constant contact with the tooth/root surface. The appropriate adaptation of curettes on tooth/root surfaces is essential to avoid any soft tissue injury.

Selection of the correct working end and cutting edge:

There are multiple methods to identify a correct working end. The most common method is to identify the working end, which should be directed towards the surface to be debrided. For example, to debride the mesial and the buccal surface of the mandibular first molar the toe of the curette should be directed towards the mesial surface. This can easily be identified by closely adapting the curette on the tooth surface. Only the correct end of a bi-ended instrument with appropriate angulation of the cutting edge will adapt closely to the surface to be debrided.

The second identifying method is the position of the terminal shank. With the position of instrument handle as parallel as possible with the tooth in buccolingual direction, the terminal shank is nearly parallel to the proximal surface of the tooth for a correct working end. On the other hand, if the terminal shank crosses the proximal or buccal/lingual surfaces diagonally or horizontally, the incorrect working end is adapted.

The correct cutting edge for area specific curettes can be identified prior to adaptation by viewing the instrument and looking at the face of the blade when it is held so that its terminal shank is perpendicular with the floor. The correct cutting edge is one which is large and has a convex curve. This cutting edge is farthest from the blade handle and is also designated as inferior cutting edge or leading edge.

Adaptation of the working end:

Once the explorer or curette has been inserted into the gingival sulcus or pocket, 1-2 mm of the terminal 1/3rd of the working end is adapted to the tooth surface, especially at line angles of convex surfaces and concave surfaces of the developmental depressions. If middle 1/3rd is adapted to tooth surface rather than terminal 1/3rd, the tip or the blade frequently results in soft tissue trauma causing discomfort to the patient.

Terminal 1-2 mm of the working end is adapted diagonally to the calculus deposit. This is because if the entire working end is adapted to the surface, the borders and configuration of the deposit cannot be determined. Also, the tactile sensation is reduced when the entire working end is in contact with tooth surface as compared to the terminal portion of the working end. Another reason for adapting the working end of the curette diagonally is that if a large calculus deposit is present, it needs to be fractured and removed in pieces. This fracturing requires the positioning of curette in a diagonal manner because if the entire working end is adapted, the excessive lateral pressure is required to initiate fracturing.

Establishing appropriate blade angulation:

After adapting the working end of the instrument on the tooth surface, appropriate blade angulation is established so that the desired result can be achieved once the stroke is made. The range of angulation of an instrument when it is applied on cementum, enamel or calculus is greater than 45⁰ to less than 90⁰. If the angulation is less than 45⁰, it will lead to burnishing of the deposit whereas if it is more than 90⁰, it will remove the soft tissue pocket lining (gingival curettage). For curettes, the ideal angulation for scaling and root planing is 70⁰ to 80⁰. A detailed description of curette adaptation and activation on the tooth surface has been given in “Periodontal instruments”.

Activating the instrument:

The activation of the instrument involves a combined motion of the hand, wrist and forearm to produce an appropriate stroke to assess or debride the tooth surface. The clinician activates an instrument with wrist-arm motions that roll from the fulcrum finger. The pressure exerted against the fulcrum is a critical component of activation. The wrist flexion……………….

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However, while working on a particular tooth surface one of these motions predominate. Rolling and pivoting motions are required to maintain the adaptation of the working end with the tooth surface during stroke especially at line angles of the tooth.

The pressure applied during making a stroke depends upon the desired action. When removing calculus, initially firm or moderate pressure is applied, which is then progressively diminished, whereas light pressure is applied when root planing is to be done. If insufficient lateral pressure is applied for removing heavy calculus, a burnished surface of calculus may result which is difficult to detect and remove. On the other hand, the uncontrolled heavy force application may result in nicking or grooving of the root surface. Hence, during instrumentation, application of a well-controlled lateral pressure is required to effectively perform scaling or root planing.

Strokes during instrumentation:

During periodontal instrumentation, three types of activation strokes are used: assessment stoke (exploratory stroke), calculus removal stroke (scaling stroke) and root planing stroke 1. These strokes may be activated in vertical, horizontal or oblique direction. Vertical and oblique strokes are most commonly used during periodontal instrumentation. Horizontal strokes are used primarily on tooth line angles and in deep periodontal pockets were vertical or oblique strokes are difficult to apply. The factors that determine pressure, length and number of strokes are,

  • Amount and nature of calculus to be removed,
  • Tone of the soft tissue,
  • Contour of the tooth, and
  • Pocket depth and shape.

Assessment (exploratory) stroke:

These strokes are used to evaluate root surface anatomy, surface irregularities, presence of calculus on the root surface and other plaque retentive factors. As the name “exploratory” indicates, these strokes are light strokes applied on the root surface to assess root surface condition. The instruments that are used to assess root surface with exploratory stroke include explorers, probes, sickles, and curettes. During activating these strokes, the instrument is held with light pressure and is moved with light pressure against the tooth surface so that maximum tactile sensitivity is achieved. The best guide to apply light pressure is not to apply any lateral pressure consciously. The strokes applied are of moderate length and must overlap on all surfaces.

Calculus removal (scaling) stroke:

These strokes are employed with calculus removing instruments such as sickles, curettes, and files. These are also used to remove overhanging restoration margins. While activating these strokes, lateral pressure is applied on the cutting edge of the instrument to remove the supra- or subgingival calculus deposited on the tooth/root surface.

The initial step in the activation of scaling stroke is the establishment of a firm grip over the instrument with the help of finger rest. The amount of pressure applied depends on the purpose of stroke and class of instrument used. According to the pressure to be applied during making the stroke, pressure is applied on the finger rest on the tooth on which the finger rest has been established. As the pressure applied by finger rest is on the tooth, the patient feels light pressure and not discomfort. Now, the index finger and thumb are flexed slightly to exert pressure on the instrument and in turn on the tooth surface. The pressure must be equally distributed between the thumb and index finger otherwise the clinician may lose the control over the instrument grasp. The instrument is best under control when the pressure is equally distributed between the index finger and thumb.

The cutting edge of the instrument is then placed below the attachment of calculus on the tooth surface and its apical border is engaged.  A firm movement in the coronal direction is then made to dislodge the calculus from the root surface. There is a combined action of the wrist and hand during this movement. Care must be taken not to move the wrist too much, otherwise, the angle made by the blade of the instrument and tooth surface will change and the desired result of the stroke will not be achieved.

“Channeling” is the procedure by which calculus deposit is removed piece by piece. The procedure is done when…………………..

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Root planing stroke:

The root planing strokes are light to moderate pressure strokes used to remove residual calculus after scaling strokes have removed the main bulk of calculus and for final smoothening and planing of the root surface. These are also used to remove the bacterial plaque and bacterial endotoxins from the root surface. These strokes are multi-directional and cover all the surfaces where instrumentation has been performed. During making root planing strokes, unnecessary removal of cementum should be avoided and strokes should be made only with light pressure.  Use of curettes with a flexible shank is recommended for root planing as these provide good tactile sensitivity and remove less cementum as compared to rigid shank curettes.

Direction of instrument stroke:

The direction of the instrument is designated by its relation to the long axis of the tooth. The instrument stroke may be vertical, oblique, horizontal or circumferential, selection of which depends on the type of instrument used and the function to be performed. Scaling strokes which utilize moderate to high pressure are applied primarily in vertical or oblique direction. Horizontal strokes are directed toward tissue and are applied with light pressure. Instrument strokes also may be described as pull, push, and walking. The pull stroke is used during scaling where after engaging the calculus the stroke is made. It is the most commonly used stroke during periodontal instrumentation. In the push stroke, the instrument is apically moved toward the gingiva. This stroke is rarely used as it may cause trauma to the gingiva. The walking stroke uses both coronal and apical movement of the working end of the instrument. It is used with explorers and probes to assess the root surface.

Conclusion

The goal of instrumentation is to ensure a clean root surface which is biologically acceptable and is the prime requirement for a healthy periodontium. If all the principles of instrumentation are followed, the chances of leaving deposits over the tooth/root surface are minimized. It must be ensured that instrumentation strokes overlap so that no portion of the tooth surface is missed. The effective instrument strokes must cover the tooth surface completely from the junctional epithelium to the gingival margin. An appropriate instrumentation causes minimum trauma to the soft tissue and minimum discomfort to the patient.

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Periobasics: A textbook of periodontics and implantology

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