Pravinkumar G Patil
Department of Prosthodontics, Government Dental College and Hospital, Nagpur, Maharashtra, India
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|Date of Submission||04-Sep-2009|
|Date of Decision||09-Sep-2009|
|Date of Acceptance||01-Oct-2009|
|Date of Web Publication||29-Sep-2010|
| Abstract|| |
This article describes a simple technique of useful modification of measuring compass, procured from a school compass box, to make an intraoral paralleling device. This device is useful in examining parallelism of tooth or implant abutment preparations for a common path of placement in fixed dental prostheses. It can be used to examine the parallelism of guiding planes in removable partial denture patients as well.
Keywords: Abutment preparation, fixed dental prostheses, guiding planes, path of placement
|How to cite this article:|
Patil PG. Modified measuring compass as an intraoral paralleling device. Indian J Dent Res 2010;21:452-3
When teeth are prepared for single crowns or abutment of fixed dental prostheses, the goal is to establish a path of placement that allows unimpeded insertion of the restoration in conjunction with an optimum convergence angle of 2.5 to 6.5 degrees to minimize stress concentrations. , When multiple abutments are being evaluated for a common path of placement; use of mouth mirror,  photographic mirror  and dental periscope  were described in previous literature. This article describes a simple technique of modification of a measuring compass (also called as a divider) to make an intraoral paralleling device. This device is useful in examining parallelism of tooth or implant abutment preparations (for common path of placement) in fixed dental prostheses. Chair-side time is reduced by eliminating the need for multiple check impressions and cast fabrication during various stages of abutment preparation. It eliminates the chances of human error by examining the preparations with mouth mirror or photographic mirror (where the preparations are examined by mirror image perception of an operator). The device is autoclavable and can be used to examine the parallelism of guiding planes in removable partial denture patients as well.
| Procedure|| |
- Procure a measuring compass (Camlin Ltd., Mumbai, India) from a commonly available school compass box [Figure 1]. Trim pointed tips of end-rods of both the arms on lathe machine (by keeping long axis of both arms perpendicular to the trimming surface) to make them flat. Trim the tips to measure the end rods approximately 1.5 cm in length.
- With the help of an orthodontic universal plier (Universal Plier, Jaypee General Agencies, Calicut, India), provide ninety degree bend to both end-rods simultaneously, keeping both arms of the compass in close approximation. This will ensure parallelism of one end-rod, at its any possible position, to the other rod, within the entire opening and closing arc of the compass [Figure 2].
- To examine parallelism of abutment preparations, keep one end-rod of the device along one axial surface and stretch other arm till next axial surface to examine the parallelism of it in relation with previous axial surface [Figure 3].
| Acknowledgment|| |
The author thanks Dr. Smita P. Patil (PG student, Dept. of Orthodontics, PMNM Dental College and Hospital Bagalkot, Karnataka, India) and Dr. Mohana Tagore (PG student, Dept. of Prosthodontics, Govt Dental College and Hospital, Nagpur, Maharashtra, India) for their help.
| References|| |
|1.||el-Ebrashi MK, Craig RG, Peyton FA. Experimental stress analysis of dental restorations: IV: The concept of parallelism of axial walls. J Prosthet Dent 1969;22:346-53. |
|2.||Jørgensen KD. The relationship between retention and convergence angle in cemented veneer crowns. Acta Odontol Scand 1955;13:35-40. |
|3.||Shillinberg HT, Hobo S, Whitsett LD. Principles of preparations. Fundamentals of fixed prosthodontics. 2nd ed. Chicago: Quintessence Publishing Co; 1981. p. 79-96. |
|4.||Dumbrigue HB, Gurun DC. Use of intraoral photography mirrors as aids for evaluating parallelism of multiple abutment preparations. J Prosthet Dent 2001;85:95. |
|5.||Patil PG, Parkhedkar RD. Dental periscope: A new device to examine the parallelism of abutment teeth. J Indian Prosthodont Soc 2008;8:27-9. |
Pravinkumar G Patil
Department of Prosthodontics, Government Dental College and Hospital, Nagpur, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]