Kourtis S

Research Article

J Dent & Oral Disord. 2018; 4(1): 1084.

A New Type of Radiographic Template for Presurgical Radiographic Examination in Implant Restorations

Kourtis S*

Department of Prosthodontics, National and Kapodistrian University of Athens, Greece

*Corresponding author: Stefanos Kourtis, Associate Professor, Department of Prosthodontics, National and Kapodistrian University of Athens, Greece

Received: December 18, 2017; Accepted: January 31, 2018; Published: February 08, 2018

Abstract

Various radiopaque materials have been used as radiopaque markers for radiographic templates. A new type of diagnostic template is presented in this article that allows radiographic imaging of the intended implant axis and the contour of the restoration in CT Dental Scan and Cone Beam Computer Tomography (CBCT). The use of amalgam powder as a coverage layer on the outer surface of a template offers detailed imaging of the restoration contour in correlation to the bone substrate. The diagnostic template can be transformed easily to an accurate surgical template.

Keywords: CT- Dental scan; CBCT; Radiographic guide/ template, Restoration contour; Dental implants

Introduction

Implant restorations need detailed presurgical planning and radiographic control. CT-Dental Scan and Cone Beam Computer Tomography (CBCT) are used extensively nowadays in the clinical practice, in order to investigate the bone substrate before implant surgery [1-4]. The most common types of diagnostic templates are constructed from autopolymerizing resin with radio-opaque materials used as markers to determine specific anatomical areas. As radio-opaque markers various materials have been used, including metal rods, titanium rods, guttapercha, barium sulfate etc [4-10].

The aim of this paper was to describe a new type of diagnostic template for CT- Dental Scan or CBCT that allows imaging of the restoration contour in relation to the bone substrate.

Technique

Study casts are mounted on a semi-adjustable articulator and a wax-up is made on the area to be restored. In cases of edentulous patients the diagnostic set-up or the existing denture (if satisfactory, as in the presented case) can be used. From the wax-up (or the existing denture) silicone impressions are made and a duplicate from heat polymerizing clear acrylic resin is fabricated. Alternatively autopolymerizing resin can be used (Figure 1).

Figure 1: The existing denture is duplicated using silicone impression material.

    
    
    Figure 1:  The existing denture is duplicated using silicone impression
material.

The acrylic teeth in the duplicate denture are drilled in the center (3 mm diameter) in a parallelographing milling device, along the desired axis of the implant. If the drillings are not necessarily parallel, as in the edentulous maxilla, a line is drawn along the axis of the tooth in the labial area with a marker and the drilling can be accomplished manually parallel to the markings. The parallel axis of the drillings can be checked visually by inserting laboratory rotating instruments in the drillings (Figure 2). The hollow space created by the drilling is filled with guttapercha (Figure 3). Alternatively titanium rods can be used as they do not cause artifacts on the CT image.

Figure 2: Lines are drawn along the teeth axes and the drillings are performed parallel to the markings.

    
    
    Figure 2:  Lines are drawn along the teeth axes and the drillings are performed
parallel to the markings.

Figure 3: The hollow spaces of the drillings are filled with guttapercha.

    
    
    Figure 3:  The hollow spaces of the drillings are filled with guttapercha.

The outer contour of the acrylic teeth is covered with amalgam powder dissolved in transparent nail varnish. The varnish is applied with a soft brush as a thin layer on the whole surface (labially and palatally) up to the cervical areas (Figure 4). The varnish layer should be restricted to the areas where implants are planned to avoid unnecessary image “noise” and to facilitate area recognition on the cross-section images of the Computer Tomography.

Figure 4: The outer surfaces of the template on specific teeth are covered with amalgam powder dissolved in transparent nail varnish.

    
    
    Figure 4:  The outer surfaces of the template on specific teeth are covered
with amalgam powder dissolved in transparent nail varnish.

The patient is then referred to perform a radiographic examination, CT Dental Scan or CBCT. On the examination of the reconstructed cross-section images the radiopaque markers can be easily identified in the specific areas and also the contour of the acrylic teeth. In this way the desired implant axis can be correlated to the existing bone substrate and the contour of the planned restoration (Figure 5,6).

Figure 5: Cross-section images of the anterior maxillary teeth. The guttapercha marker can be distinguished within the radiopaque contour from the amalgam powder.

    
    
    Figure 5:  Cross-section images of the anterior maxillary teeth. The
guttapercha marker can be distinguished within the radiopaque contour from
the amalgam powder.

Figure 6: CBCT cross-section image at the premolar region of another patient with the same type of markers.

    
    
    Figure 6:  CBCT cross-section image at the premolar region of another
patient with the same type of markers.

The diagnostic template can be easily transformed to a surgical guide by removing the nail varnish with acetone and the guttapercha from the hollow spaces. In cases of edentulous patients (as in the presented case) the anterior palatal part of the template is removed to allow better surgical approach, maintaining the guiding labial surfaces (Figure 7,8).

Figure 7: The anterior palatal part of the template will be removed for the use as a surgical guide.

    
    
    Figure 7:  The anterior palatal part of the template will be removed for the use
as a surgical guide.

Figure 8: The template transformed to a surgical guide.

    
    
    Figure 8:  The template transformed to a surgical guide.

The use of a template reproducing the desired contour of the restoration at CT-Scan images may contribute significantly to the treatment planning and provide the clinician with valuable information. In cases with severe bone resorption in the anterior maxillary region, the correlation of the restoration contour to the existing bone substrate may lead the clinician to proceed to bone augmentation or to offer to the patient a removable restoration (Figure 9,10).

Figure 9: Cross-section images of the anterior maxillary region of another patient with severe bone resorption. Amalgam powder has been used to indicate the contour of the restoration and no guttapercha has been inserted. Red line (left) indicates the prosthetically favorable implant axis and blue line (right) the axis of the implant as imposed by the existing bone substrate. In this case an augmentation procedure is necessary.

    
    
    Figure 9:  Cross-section images of the anterior maxillary region of another
patient with severe bone resorption. Amalgam powder has been used to
indicate the contour of the restoration and no guttapercha has been inserted.
Red line (left) indicates the prosthetically favorable implant axis and blue line
(right) the axis of the implant as imposed by the existing bone substrate. In
this case an augmentation procedure is necessary.

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Citation:Kourtis S. A New Type of Radiographic Template for Presurgical Radiographic Examination in Implant Restorations. J Dent & Oral Disord. 2018; 4(1): 1084.

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A New Type of Radiographic Template for Presurgical Radiographic Examination in Implant Restorations

Abstract

Introduction

Technique

Discussion

References