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Journal of LSTR Therapy (International WEB version) VOL 8: 1-2-, 2009

MP Penetration through Obturated Root Canals-A Basis for LSTR 3Mix-MP NIET retreatmentNunéz P. Phides D.D.S., Ph.D., Hiba A. Al-Shawafi, H., D.D.S. and Etsuro Hoshino, D.D.S., Ph.D.
Oral Ecology in Health and Infection, Niigata University Graduate School of Medical and Dental Sciences, Niigata,Japan
Abstract

The ability of a mixture of macrogol and propylene glycol (MP) to penetrate through root canal obturation
was tested using a total of 30 root canals of single-canal extracted teeth, being obturated using lateral
condensation method. The obturation was judged to be good radiographically. The MP + dye (Red fooddye) was placed at the orifices of root canals, and time that MP + dye exited to the root apex was measured.
In all the samples, Dye + PM passed through obturation and exited to the root apex, while water + dye did
not exit except for 3 cases. The penetration time of MP + dye was within 24 hours in 11 samples (37%), 48
hours in 8 samples (27%), 72 hours in 7 samples (23%), 96 hours in 2 samples (7%), and 112 hours in theremaining 2 samples (7%). This indicates that propylene glycol may be good vehicle to carry medicaments,
such as 3Mix-MP, through root canal obturation without removal of previous root canal obturation.
Key words:

propylene glycol, root canal obturation, root canal re-treatment

MP is the components of 3Mix-MP preparation (1-3), which
consists of a combination of 3 antibacterial drugs (3Mix)
mixed with macrogol and propylene glycol (3Mix-MP). LSTR(Lesion Sterilization and Tissue Repair) 3Mix-MP therapy has
been reported to give good clinical outcomes in the treatmentof root canals (1, 2), even without root canal preparation androot canal obturation (NIET: Non-instrumentation EndodnticTreatment). In some cases (1) endodontic treatment has
been successful without removal of previous root canalobturation. This may indicate efficient penetration efficiency
of 3Mix-MP through obturated root canals, but it is also
probable that the obturation had not been done well and was
not compactly obturated. In this report, MP penetration wastested using extracted teeth with well-obturated root canals.
A total of extracted 30 single-canal incisors with fully-formedroots was selected and each tooth after obturated using
lateral condensation method as described elsewhere (1).
The obturation was checked radiographically and judged tobe good by 4 dentists.
Macrogol (Solbase®, Dainippon Pharmaceutical Co., Meiji,Tokyo, Japan) and propylene glycol were mixed at a 1:1 ratio(MP), and MP was further mixed with a food red dye (TokyoKasei Kogyo Co., Ltd., Tokyo, Japan; MP+dye). For a control,
MP was replaced by water (water+dye). The MP-dye orwater+dye was placed at the orifice of root canal, and, then,sealed with Caviton (GC Asahi Corp., Aichi, Japan). Eachtooth was placed on separate tubes which had white paper
packed at the bottom. Care was taken to ensure contact
between the root tip and the paper so that any dye exitingfrom the apical foramen would be absorbed into the whitepaper. The time that elapsed from dye application until dye
penetration through the apex was recorded. A pink colorobserved at the apical foramen was considered as positive
dye penetration. Dye exit was checked every 15 minute forthe first hour, every 60 minutes for the next 23 hours, andevery 2-24 hours thereafter.
Accepted: Aug. 1, 2009
Published: Aug 18, 2009

In all samples tested, the MP+dye mixture penetrated
through the obturation and exited to the root apex (Table).
However, the dye exited taking rather long time except for 4
cases, in which the dye exited within 2 hours. The mean timeof dye-exit was 44 hours, ranging from 0.5 hour to 112 hours.
Out of 30 cases, within 24 hours dye exited through theapical foramen in 11 cases (37%), within 25-48 hours in 8cases (27%) and within 49-3 days in 7 cases (23%). Dyeexit was recognized in 2 cases (7%) after 4 days and in theremaining 2 cases (7%) before 5 days. On the contrast,
when the dye was mixed with water (water+dye), dye did notexit to the apex in almost all (90%) cases except for 3 cases(Table).
The present result clearly demonstrated that MP carrieddyes through root canal obturation and exited to apex
foramen. The efficient penetration of propylene glycol within
dentin through dentinal tubules has also been demonstratedby Cruz et al (4) who have shown when propylene glycol isapplied at the orifices of unfilled root canal, it diffuses toentire dentin within a minute in most cases. In the present
study, we use the root canals obturated well using lateral
condensation technique, and the obturation was judged to begood radiographically. However, it has been demonstrated(5) that, even root canal obturation is evaluated will using Xray photes two-dimensionally, defects/spaces between dentin
surfaces and obturation materials, and within/between
obturation materials, are easily hidden, but when the sameobturation was observed 3-dimentionally using the microcomputed tomography, the hidden defects are recognized(Table) in all cases.
It was probable that such defects/spaces are generated
because of minute air-bubbles formation within obturation, of
the complicated root canal structures like fins and isthmuses,boundary problems between root canal wall dentin andobturation materials, etc, and they may further form channels
or tunnels within obturation to allow MP penetration and exit.

Phides et al.

MP penetrates through obturation

Table. Penetration of Propylene Glycol through root canal
Obturation

Sample Number
12
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

Dye Penetration Time
Dye + MP (hours)
Dye + water
0.5
2
22
15
19
22
22
23
23
24
36
39
40
48
48
48
48
48
55
56+60
60+64
64
72
96
96
104+112-These may also indicate, when MP is used as 3Mix-MP in
LSTR 3Mix-MP therapy, MP delivers 3Mix and kill bacterial inendodontic lesions.
In fact, clinical studies havedemonstrated that LSTR 3Mix-MP therapy has been highly
successful in the re-treatment of root canals which had had
been previously treated and obturated but failed (6).
Acknowledgments: This research has been supported by
Grants-in-Aids for Scientific Research 1440628 and17390500 and JSPS Joint Research Projects 151075 and151076.
References
1. Takushige T, Hoshino E: Clinical evaluation of 3Mix-MP
method in endodontic treatment. Jap J Conserv Dent 1998;
41: 970-4 (in Japanese with English Abstract).
2. Takushige T, Cruz EV, M A. Asgor M, Hoshino E:
Endodontic treatment of primary teeth using a combination ofantibacterial drugs. Int Endod J 2004; 37: 132-8.
3. Takushige T, Cruz EV, M A. Asgor M, Hoshino E: Nonsurgical treatment of pulpitis, including those with history ofspontaneous pain, using a combination of antibacterial drugs.
Journal of LSTR Therapy (International WEB version) 7: 1-5,
2008.
4. Cruz EV, Kota K, Huque J, Iwaku M, Hoshino E:Penetration of propylene glycol through dentine. Int Endod J
2002; 35: 330-6.
5. Phides NP, Hoshino E: Evaluation of Obturation by ImageAnalyses and Macrogol and Propylene Glycol Penetration.
Journal of LSTR Therapy (International WEB version) VOL 7:6-10, 2008
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6. Takushige T, Hataoka H, Ando M, Hoshino E:
Endodontic Retreatment using 3Mix-MP without Removal ofPrevious Root Canal Obturation. J LSTR Ther 2009; 8: 3-7.

Journal of LSTR Therapy (International WEB version) VOL 7: 6-10, 20088