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TECHNICAL NOTE
Year : 2018  |  Volume : 8  |  Issue : 1  |  Page : 116-117

Osteosynthesis using the uncalcined and unsintered hydroxyapatite / Poly-L-Lactic acid system


Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan

Date of Web Publication12-Jun-2018

Correspondence Address:
Dr. Hiroyuki Nakano
Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka 812-8582
Japan
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DOI: 10.4103/ams.ams_192_17

PMID: 29963435

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  Abstract 


The poly-L-lactic acid mini-plate system accomplished rapid development. However, the system still has a variety of problems. One such problem is the breakage of screws. In this technical report, we develop the temporary fixing screws made from stainless with hexagon steel that exhibit a hexagonal head and thread part that also features a tapping function.

Keywords: PLLA mini-plate system, reconstruction surgery, temporary fixing screws


How to cite this article:
Nakano H, Inoue K, Sumida T, Yamada T, Mori Y. Osteosynthesis using the uncalcined and unsintered hydroxyapatite / Poly-L-Lactic acid system. Ann Maxillofac Surg 2018;8:116-7

How to cite this URL:
Nakano H, Inoue K, Sumida T, Yamada T, Mori Y. Osteosynthesis using the uncalcined and unsintered hydroxyapatite / Poly-L-Lactic acid system. Ann Maxillofac Surg [serial online] 2018 [cited 2019 May 26];8:116-7. Available from: http://www.amsjournal.com/text.asp?2018/8/1/116/234291




  Introduction Top


The poly-L-lactic acid (PLLA) mini-plate system is one of the various bioabsorbable materials that are used during plastic and reconstruction, orthopedic, craniofacial, and oral, and maxillofacial surgeries. This is because the system was rapidly developed and deployed. Despite its widespread use, the breakage of mini-screw heads regularly occurs during screw removal. Therefore, we developed temporary fixing screws made from stainless steel that exhibit a hexagonal head and thread and features a tapping function because uncalcined and unsintered hydroxyapatite (u-HA)/PLLA screw is very expensive.


  Technical Note Top


The application of the temporary fixing screws in clinical practice is described for a hypothetical plate with four holes. First, holes are made using a drill, and the temporary fixing screws are placed into the two medial holes [Figure 1]. Second, u-HA/PLLA screws are placed into the two external holes that were created using the thread portion of the tapping driver. Finally, the temporary fixing screws are replaced by the u-HA/PLLA screws without tapping [Figure 2] and [Figure 3].
Figure 1: First step: The temporary fixing screws are used to construct two medial holes

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Figure 2: Second step: The temporary fixing screw is removed

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Figure 3: Final step: The temporary fixing screws are replaced by the Super-Fixsorb MX® screws without tapping

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  Discussion Top


In the past, several researchers have reported the utility of the PLLA plate system (Fixsorb™-MX; Takiron, Osaka, Japan) as well as of the conventional titanium mini-plate system. Recently, a new bioabsorbable mini plate system has been developed, which is made of forged composite material containing u-HA particles and PLLA (u-HA/PLLA system: Super Fixsorb™ MX; Takiron, Osaka, Japan).[1],[2],[3] This u-HA/PLLA system is stiff, completely bioabsorbable, and osteologically bioactive. Moreover, it exhibits a stronger fixation power than the PLLA system. Therefore, the thickness of the plate was changed from 1.5 mm to 1.0 mm, thereby reducing the sensation of the presence of a foreign object in the patient's body. As a result, we aggressively use the u-HA/PLLA system for orthognathic surgery, particularly for Le Fort 1 osteotomies, since there is no need for a second operation to remove the implant.

Nevertheless, the u-HA/PLLA system is complicated by the susceptibility of the screw heads to breaking if a sufficiently strong force is applied. Therefore, an exclusive driver system that contains a clutch with limited torque is needed, which can prevent the breakage of screw heads since the clutch detaches when the screw is fully inserted. However, the breakage of the mini-screw head still can occur when these screws are removed, possibly because the removal system does not have a clutch function when inverse rotation is applied. The u-HA/PLLA plates are placed in the lateral border of the piriform aperture and bilaterally in the lower ridge of the zygomatic bone during Le Fort 1 osteotomy. At that time, the u-HA/PLLA screw often has to be removed because the bone of the lateral border of the piriform aperture is often thin.

Therefore, we developed the temporary fixation screw system to address this problem. In general, the u-HA/PLLA screw is placed after tapping. Therefore, we developed a temporary fixing screw made from stainless steel with a hexagonal head and thread part that features a tapping function. When using this method, it is not necessary to remove the u-HA/PLLA screws. Moreover, our system is sufficiently simple to operate. Finally, use of the temporary fixative screws will be done with greater confidence as the use of the system increases.


  Conclusion Top


We believe that this temporary fixing screw system is remarkably valuable and economical.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Shikinami Y, Okuno M. Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly-L-lactide (PLLA): Part I. Basic characteristics. Biomaterials 1999;20:859-77.  Back to cited text no. 1
[PUBMED]    
2.
Shikinami Y, Okuno M. Bioresorbable devices made of forged composites of hydroxyapatite (HA) particles and poly L-lactide (PLLA). Part II: Practical properties of miniscrews and miniplates. Biomaterials 2001;22:3197-211.  Back to cited text no. 2
[PUBMED]    
3.
Shikinami Y, Matsusue Y, Nakamura T. The complete process of bioresorption and bone replacement using devices made of forged composites of raw hydroxyapatite particles/poly l-lactide (F-u-HA/PLLA). Biomaterials 2005;26:5542-51.  Back to cited text no. 3
[PUBMED]    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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   Abstract
  Introduction
  Technical Note
  Discussion
  Conclusion
   References
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