Fragment Retrieving Apparatus (FRA) for removal of broken instrument or file fragment from the root canal of tooth.

Abstract

The separation of an endodontic instrument during a root canal procedure is one of the most common endodontic mishaps. During routine therapy, at any stage, an endodontic instrument (endodontic K-files) can fracture due to flexural fatigue, torsion or due to excessive torque, during canal negotiation or shaping, inadequate access or visibility in the root canal during endodontic procedures. The incidence rate of intracanal fracture of endodontic hand instruments ranges between 0.25% and 6% (Crump & Natkin, 1970; Hülsmann & Schinkel, 1999; Iqbal et al., 2006; Spili et al., 2005).. A separated instrument (SI) poses major challenges, including the possibility of intracanal corrosion and limited or no accessibility for chemo mechanical preparation of the canal apical to the SI. Hence, retrieval of broken instrument is necessary to gain access to the entire length of the root canal. Generally, mechanical methods for instrument retrieval can be classified into two groups, namely those involving trephine burs to trough the fractured instrument periphery in the preparation step followed by removal attempts using various devices and those involving ultrasonics or special files to create a tiny space only on the side of the fractured instrument in the preparation step followed by removal attempts using devices or ultrasonics. Mechanical devices involving trephine burs include the Masserann Kit (Micro-mega), Cancellier Extractor Kit (SybronEndo), Endo Extractor (Brasseler Inc.), Endo Rescue (Komet/Brasseler), Micro Retrieve & Repair System (Superline NIC Dental) and iRS (Dentsply Tulsa Dental). Also, recently, XP Endo shaper and XP Endo Finisher file systems are available for removal of the nonvisible fractured instrument. However, all these devices and methods requires creation of a a thin space between the canal wall and the fractured instrument apart from extensive dentin removal along the inner canal wall for loosening of the fractured file. This results in the decrease in fracture resistance of radicular dentin which ultimately leads to a poor prognosis of the particular tooth. Hence, a new and effective device is needed which should overcome the above shortcomings and increase the prognosis of the tooth. Our Fragment Retrieving Apparatus (FRA) is planned to work in such a way that there will be minimum requirement for removal of radicular dentin for retrieving fractured instrument or files and this will result in the preservation of sufficient dentin thickness at the same time. Also, the tooth can be saved from undergoing endodontic surgery or extraction once the fractured instrument is removed.

Specification

Description:FRA will be made for precise and stable grasping of various shapes and sizes of files and broken
instrument. The gripper is designed to be compact, allowing it to be used in root canal of the
tooth during endodontic procedure. The FRA will be constructed using the sliding mechanisms
which encourage the opening and closing of the jaws for proper grip and extraction of the
broken instrument from the root canal during endodontic procedure
Components-
1. Central rod: The central rod will be embedded into the main external rod (the base
structure of instrument) and glides in it with grease mechanism.
2. Gripper Jaws: Are the parts that will actually grip the broken instrument, usually
located at the ends of the FRA tool. The gripper jaw will be angulated for proper
mechanism of the apparatus.
3. Striated terminal end of jaws: The terminal ends of the gripper jaw will have
striations for precise grip of broken instrument or files during endodontic procedures.
4. Base: That part of FRA structure which will support the entire mechanism i.e.
external hollow cylinder.
Mechanism of action-
The instrument will be constructed on the basis of sliding tube mechanism in which the inner
I-shaped cylinder will help for movement of the jaws of the FRA tool. The FRA will be easy
to use and can be operated manually to retrieve the broken fragment of file or instrument in
root canal during endodontic procedures.
Opening of the jaws (Input Motion) -
The inner angulated jaw arm will be articulated between the I-shaped inner cylinder which will
help to manipulate the opening and closing of the jaws. For opening of the jaw, the inner
cylinder needs to be pushed in so that the lower side of the I-shape cylinder will hit the inner
angulated jaw arm which will deliver force on the pivot joint and ultimately causes opening of
the jaw of the FRA tool.
Closing of the jaw (Gripping Action) -
For closing the jaws, the inner cylinder needs to be pulled out so that the upper side of the I
shape cylinder will hit the inner angulated jaw arm which will deliver force on the pivot joint
and ultimately cause closing of the jaw of the FRA tool. Once the broken instrument will be
gripped it can be confirmed by radiographic evaluation then the FRA tool can be held with the
forceps and can be removed easily. , Claims:1. This FRA tool will help in retrieval of broken instrument from the root canal of tooth.
This FRA tool will be precisely designed with above mentioned specific dimensions.
2. Due to increase refinement of this innovative tool, there will be no need for trephination
and loss of tooth structure could be minimized.
3. Finely designed FRA tool with very less dimensions.
4. Sliding mechanism of action.
5. Components including hollow tube, two angulated gripper jaw, the inner cylinder with
I-shaped upper end
6. Easy to use because of simple mechanism.

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