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2 Armamentarium

LEARNING OBJECTIVE

At the end of the chapter, the student should have knowledge of the various applications of the armamentarium used for tooth carving and wax‐up technique.

Wax Block

Carving wax (Figure 2.1) is used in dentistry to study and simulate dental anatomy.

Content of carving wax includes

1 Paraffin wax (55–60%)Solid hydrocarbon mixture obtained from petroleum products. The straight‐chain hydrocarbon has 26 carbon atoms.

2 Beeswax (5%)Obtained from honeycombs. Composition includes ester complex mixture, saturated and unsaturated hydrocarbons, and high molecular weight organic acid. Two types of beeswax are used: yellow beeswax and bleached beeswax.

3 Carnauba wax (25%)An exudate obtained from the pores of the leaves of the Brazilian wax palm tree (Copernicia prunifera). It is used to increase melting point and hardness of the paraffin.

4 Inorganic filler (10–15%)Most commonly used filler particles are silica and calcium bentonite. Increases hardness, linear thermal expansion, and melting point of carving wax. Filler materials are also added to increase toughness, improve accuracy, obtain smoother carving, avoid bubbles and flaking, and free models and instruments from tackiness [1, 2].

Inlay Wax

Inlay wax is used in waxing or building the anatomy of the tooth for crowns and bridge units that are formed by a casting process using lost‐wax pattern technique. It may contain 60% paraffin, 25% carnauba, 10% ceresin, and 5% beeswax. Based on their flow, inlay waxes are classified as hard, regular (medium), or soft. The flow of the inlay wax can be reduced by increasing the percentage of composition of carnauba wax or by adding a paraffin wax with a higher melting point or small amount of resin. Inlay waxes are available in various colours such as deep blue, green, or purple and in various forms such as small pellets or cones or in jars [3].

Lecron Carver

The Lecron carver is a stainless‐steel instrument used for carving tooth morphology on carving wax. It is also used for carving on inlay wax [4].

It has the following parts (Figure 2.2):

1 The knife end

2 The spoon end/excavating end

3 The handle

4 The shank

The Knife End

Cutting Edge

The knife end has a cutting edge or blade which has a curved anterior part (Figure 2.3a). This edge is used for carving bulk wax. This part of the cutting edge also helps in creating concavities (Figure 2.3b) on the wax surface (eg, in creating the concave lingual or palatal outline of the anterior teeth) [5].

Figure 2.1 Rectangular wax block used for carving human dentition.

Figure 2.2 Parts of the Lecron carver.

Figure 2.3 Edges of the knife end of the Lecron carver.

Non‐cutting Edge/Side

The non‐cutting edge/side is used for smoothing wax and creating the slopes of the triangular ridge. Figure 2.4 shows the carving of the mesial slope (2.4a) and distal slope (2.4b) of the mandibular first molar mesiobuccal cusp.

The Spoon End/Excavating End

This end is used in carving lingual or palatal fossae on the crown of anterior teeth and developmental depression on the roots of all teeth (Figure 2.5a–d), by excavating wax [6].

The Handle

This part of the instrument is used to hold the carver (Figure 2.2) [7].

The Shank

The shank connects handle to knife (Figure 2.2). It may be either straight or angled. In carvers the shank is straight [8].

Figure 2.4 Carving the slopes of the triangular ridge using the non‐cutting side of the carver.

Figure 2.5 (a–d) Carving the developmental depression on the root portion using the spoon end of the carver.

Metallic Scale or Ruler

The metallic scale (Figure 2.6) is used to measure the dimension of the carving before and after the carving procedure.

Vernier Caliper

The Vernier caliper (Figure 2.7) is an aid used to measure

1 Diameter of a small spherical/cylindrical body

2 The dimensions of a given regular body of known mass and hence to determine its density

It has a main scale and a sliding Vernier scale and four jaws [8].

Waxing Instruments

Based on their use waxing instruments are classified as wax addition, carving, or burnishing. PKT instruments (Figure 2.8) used for waxing technique were designed by Dr. Peter K. Thomas. PKT no. 1 and no. 2 are used for adding wax. (They can also be used for burnishing.) PKT no. 3 is a burnisher for refining the occlusal anatomy, and PKT nos. 4 and 5 instruments are wax carvers. For larger increments of wax, PKT no. 1 is used; for smaller increments, PKT no. 2 is used. A no. 7 waxing spatula is used for adding large increments of wax, especially for the initial coating. Wax is melted by heating the instrument first near its shank, then touching the wax and quickly reheating the shank [9].

Figure 2.6 Metallic scale with markings in centimetres.

Figure 2.7 Vernier caliper.

Figure 2.8 PKT instruments set.

Instrument Grasps

The modified pen grasp improves the tactile sense. The pads of the thumb and of the index and middle fingers contact the instrument, while the tip of the ring finger (or tips of the ring and little fingers) is placed on the opposing hand to obtain the rest (Figure 2.10a and b) [7].

Figure 2.9 Pen grasp.

Figure 2.10 Modified pen grasp used for holding the instruments.

References

1 1 Widjijono Widjijono, Purwanto A, Dyah I. (2009).Mechanical properties of carving wax with various Ca‐bentolite filter composition. Dental Journal 42. (3): 114–117

2 2 Widjijono (2009). Correlation between calcium bentonite concentration and paraffin wax to the hardness of carving wax. Dental Journal 14 (1): 20–23

3 3 Craig, R.G. and Powers, J.M. (2012). Restorative Dental Materials, 11e. St. Louis, MO: Mosby.

4 4 Tony, J., David, G.P., Christopher, W.S., and David, G.W. (2016). Basics of Dental Technology: A Step by Step Approach, 2e. West Sussex: Wiley Blackwell.

5 5 Veecarestores (2019). Lecron carver: Use in dentistry. https://veecaredentalinstruments.tumblr.com/post/189770090499/lecron‐carver‐use‐in‐dentistry (accessed 19 March 2020).

6 6 Medical Tools (2020). Lecron wax carver. https://medical‐tools.com/shop/lecron‐wax‐carver.html (accessed 19 March 2020).

7 7 Harald, O.H., Edward, J.S., and Andre, V.R. (2013). Sturdevant's Art and Science of Operative Dentistry, 6e. St. Louis, MO: Elsevier.

8 8 National Council of Educational Research and Training (n.d.). Experiments. http://ncert.nic.in/ncerts/l/kelm102.pdf (accessed 19 March 2020).

9 9 Stephen, F.R., Martin, F.L., and Junhei, F. (2016). Contemporary Fixed Prosthodontics, 5e. St. Louis, MO: Elsevier.