Simple Templates for Predictable, Minimally Invasive Axial Walls Preparation

Research Article

A Case Report. J Dent & Oral Disord. 2018; 4(2): 1087.

Simple Templates for Predictable, Minimally Invasive Axial Walls Preparation

Smarandescu D*

Str. Banu Dumitrache 33, Bucharest, Romania

*Corresponding author: Dragos Smarandescu, Str. Banu Dumitrache 33, Bucharest, Romania

Received: January 04, 2018; Accepted: February 07, 2018; Published: February 22, 2018


Statement of the Problem: There is often a problem to make parallel preparation of multiple abutments

Aim: To reproduce intra-orally the preparation that has been previously carried out on a diagnostic cast.

Materials and Methods: After initial impression in silicones, the diagnostic cast is being developed. The abutments are milled individually, the tip of the bur (torpedo) accurately following the finish line. On the remaining occlusal/ incisal surface of each tooth block-out resin is applied. Resin occlusal templates are obtained, which are placed intraorally on respective teeth and fixed with bonding, without etching the tooth surface. During preparation the bur (same dimension and shape as the one used while milling the cast) follows a vector that stretches from the margins of the template to the finish line. Parallel axial surfaces are prepared. Further vestibular and occlusal/incisal reduction is then carried on.

Results & Conclusion: The abutments will be ideally parallel, with minimum loss of tooth substance.

Keywords: Minimally invasive; Predictable preparation; Guided preparation


Preparing parallel abutments may be a difficult task, especially when:

Geometric concepts have been presented and thought to help improve the quality of preparations [1-3]. They are currently the most widely used method of teaching students in dental universities worldwide. However, Gold [4]. has shown that “casts from a number of preparations by dentists with a variety of fixed prosthodontic experience levels were surveyed, and the preparations were commonly found to contain undercuts, over tapered surfaces, and lack of a parallel path of insertion.” He therefore suggested the use of an intra-oral paralleling device.

The option for such a device for intra-oral surveys has stirred the imagination of inventors [5-7], and many articles in prestigious journals point to the importance of their use [8-13].

Dental inspection mirrors with paralleling guiding lines have also been patented [13,14].

In 1989, Möllersten showed that “compared with results from a previously performed model study carried out during ideal preparatory conditions, the current investigation showed that the paralleling precision of guiding instruments used clinically in fact decreases considerably, remaining, however, at an acceptable level.” [15]. In the same year [16], he compared guided and freehand preparations and concluded that “both instrument preparation and freehand preparation were influenced by the dentist’s dexterity and technical capability”, showing that paralleling devices do not seem a reliable solution thus far, though they might be of help. Other options for parallel abutment preparation include pins, jigs, and templates, placed intra-orally on the teeth to be milled.

Resin jigs have been designed as aids to parallel guiding plane preparation for removable partial dentures [17,18].

Resin templates have also been designed for easing the task of abutment preparation [19,20]; a preparation technique of this type is described in this article.


The method described below allows the clinician to reproduce accurately in the oral cavity the preparation of the patient’s teeth that was previously carried out on a diagnostic cast. Ideally, the cast is to be milled with the use of a parallelometer. What has been achieved on the diagnostic cast can then be easily reproduced intra-orally.

Methods and Materials

For the experiments on casts and on extracted teeth, impressions were taken with condensation-type silicones, and casts were developed with class III plaster. For the clinical cases, initial impressions were taken with C-type silicones, and the final impressions were taken with A-type silicones. For the casts of the clinical cases, we used class IV plaster. The technique described below also implies the use of self- or light-curing pattern resins.

Description of the method

The example is of two molars and the corresponding diagnostic casts.

1. One lower right second molar is placed in a plaster base (class III plaster; color: pink) that reaches the dentin-enamel junction. An impression is taken, and the diagnostic cast is developed (class IV plaster; color: ivory) (Figure 1). Then, a parallelometer and a torpedo diamond bur are used for the preparation of the cast (Figure 2). A pencil is used to mark the occlusal line angle resulting after the preparation of the axial walls (Figure 3). For accurate reproduction, on the real tooth, of the preparation that was carried out on the diagnostic cast, the occlusal line angle is first transferred from the cast to the tooth. This is easily done by making a resin template on the cast after preparation and insulation with water base gel (Figure 4), then fixing the template with regular bonding to the occlusal surface of the tooth to be milled (Figure 5). The tooth preparation is then carried out, with the same type of bur as that used to mill the cast. As the tip of the bur follows the finish line marked by the retraction cord (blue), the turbine is guided to bring the bur into contact with the resin template (Figure 6). In this way, the “vector” of the bur is guided by the template, which is why we call this the “template-guided vector” (TGV) technique.