(CIinical Report) Matsumoto Shigaku 20 : 197--2o2, 1994
key words : periotest value - 2-piece implant - Periotest@Clinical Applicability of the Periotest[•›!Y]for Implants
SHOGO KANDA and YUKITADA HYO
DePartment of Oral Szarge7pa, Kyoto IVational(Chief: Y. Hyo)
HosPital
Summary
It is necessary to establish objective criteria for determining the optimal time to
connect the super structure to the implant.
Several studies have examined the usefulness of the Periotest @ for determining this timing. However, few investigators have studied the usefulness of this test, based on
analysis of the reproducibility of the periotest @ values (PTV). We are studying the clinical applicability of the Periotest for POI 2-Piece implants,@ using a post specially designed for this test. The results obtained were as follovgTs.
1 . It seems possible that the Periotest @ allows surgeons to predict the prognosis of implants based on an analysis of the time course of PTV for the same type of implants and
to determine the optimal time to connect the super structure to the implant. In our
department, a PTV below +9 is regarded as indicating the optimal timing of super
structure connectlon.2. It seems possible that the Periotest@ can be used in judging whether or not a 2-piece implant@ should be connected to natural teeth or that the optimal post can be
selected based on an analysis of the PTV of natural teeth.
3. The Periotest@ seems to allow surgeons to check that an implant has been
bicortically inserted. This check seems to be most useful when it is done immediately after implant insertion. In practice, however, the use of the Periotest @ for this check immediate-ly after implant insertion is not possible because the accuracy of drilling differs amongdifferent surgeons. The Periotest@ may therefore be used in making such a check at the time of super structure application and in predicting long-term prognosis after super
structure application. Although the Periotest @ seems to be clinically applicable to these purposes, it seems indispensable to pay attention to the reproducibility of the PTV and to
standardize the conditions for PTV measurement.
Introduction
Although the optimal timing for attaching the super structure (crown, dentures, bridges, etc.) to the implant is often considered to be about 6 months after implant insertion in the maxilla and about
198 Kanda and Hyo : Clinical App]icability of the Periotest@ for lmplants
3 months after implant insertion in the mandible the determination of the optimal timing in
individual cases depends greatly on the judgment of the surgeon, based on assessment of the clinical symptoms. Thus, it is necessary to establish objective criteria for determining the optimal time to
connect the super structure to the implant. Several studies have examined the usefulness of the
Periotest@ for determining this timing. However, few investigators have studied the usefulness of this test, based on analysis of the reproducibility of the Periotest@ values (PTV). We are studying the clinical applicability of the Periotest@ for POI 2-piece implants@, using a post specially designed for this test. Preliminary results of this study are presented here.
Materials and Methods
1. Test piece
POI2 piece implants@ (Kyocera Co.) were used for this study. 2 . Apparatus and the Periotest@ post
1 ) The Periotest@ used is a product of the Siemens Co. (Fig. 1). When the start button on the hand piece is pushed, while the hand piece is held O.5-2,5 mm away from the tooth surface, a metal rod is pulsed at a rate of O.2 mm/sec. The frequency of the rod vibrations is 41sec (16 pulses in total). The duration of the contact betvLTeen the rod and the tooth surface during the pulses is measured,
using a microaccelerometer. The data are processed, using a microprocessor, to yield the PTV, using the predesignated equation. The PTV is displayed as a value in a range between -8 and +
50 (Table 1)i'.
2) Post for Periotest@
The usefulness of a post for the Periotest@ has been endorsed by Kanada et a12). The use of this post elevates the reproducibility of the PTV to a clinically acceptable level. The post can be simply manufactured. That is, 5 mm pieces of plastic connectors are cast, and a 10 mm grip is then soldered to the head of the coronal screw. We took care not to allow the total length of the post to rise over 20 mm. This limitation is necessary to permit the Periotest@ to be used within the entire oral cavity
(Fig. 2 and 3).
3. Measurement
1 ) The PTV was always measured by the same examiner.
2 ) A post was used for the PTV measurement.
3 ) PTV was measured at a point 5 mm above the gingival margin. That is, the tip of the post was
driven with a hammer.
Table 1, Relationship between clinical dental mobility and Periotest@ values
CLINICALDENTAL
PERIOTEST
clinicalviewMOBILITY
value o-8--+9
physiologicalsymptom 1+10--+19
Pl--2 2+20-+29
P2--3 3+30-+50
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o
' ' ' ' 1 t. .. t..tlt..t tl t.t t t Post for PTV tA*capa..,.1, i,1 i', , ,.1 •i,'11:'i•1111iiiiil,il,lllll[IS.t:•-,lili '' ' - t/,/ :-.. :t,:
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tt. t ,/.' L., '1 t tt t /l t/t]: ttl ' ''t"/'- :;"'1'i-ti"t"": ,i '.,-'••.',••i-',l,;--/"tt:-1 . . ,, ,.,, •- ,-iL.• iti,il•//lgii measurement 20Åq2) 1994 199Fig. 3. The PTV measuring post in the oral
cav!ty
4 ) For each point, 3 measurements were taken. The most frequent value was adopted as the PTV
for a given point.
Analyses
1 . PTV measurement using piaster models
A POI 2 piece implant@ (32-18F) was inserted into a plaster model. First, the PTV was measured during the condition when the 5mm screw post, 5mm straight post and the post for measurement were completely locked. In subsequent measurements, these posts were loosened by
turns of 45 degrees at a time (Fig. 4)
2 . PTV measurement in clinical cases
The PTV was measured for 15 POI 2 piece implants@ i'nserted into patients at the Department of Oral Surgery, Kyoto National Hospital between January 1992 and September 1992. The post for PTV measurement was used in each case.
Results
1 . When the PTV of the posts in plaster models were examined in a completely locked condition, the PTV was -2 for the 5 mm straight post, -2 for the PTV measuring post and -1 for the 5 mm screw post. When the posts were loosened by turns of 45 degrees, the PTV was +12 for the 5 mm straight post and the PTV measuring post, and +8 for the 5 mm screw post. When the posts were
Fig.4, Plaster model
PTV +50 +40 +30 +20 +lo o
/
/
1
+] ..i+8
1 / / / / , +50 / straight post +32 PTVmeasuring post . +16 screw post Fig. 5. -I' -3o" 4so
Changes in the following lock90" Angle
PTV of various posts screw leosening200 Kanda and Hyo: Clinical Applicability of the Periotest@ for lmplants
loosened by turns of 90 degrees, it was +50 for the 5 mm straight post, +32 for the PTV measuring post and +16 for the 5 mm screw post (Fig. 5).
2 . The width of the implants inserted into our patients was 3.2 mm in 13 implants and 3.7 mm in
2 implants (Fig. 6).
3 . Even when the width and the length of the intraosseous segment of the implants were the same,
the PTV varied greatly among individual implants.
PTV +lo +9 +8 +7 +6 +5 +4 +3 +2 +1 . . . . . . . . . : : : : :
.
: : . : : . : : : : : : : : : : '32 32 32 32 37 37
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ll 13 l7 19 11 13
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implantsizeThe length of the inserted segment of implants and their PTV
PTV +10 +9 +8 +7 +6 +5 +4 +3 +2 +1
o
o
o
e
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o
o
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Fig. 6. PTV +lo +9 +8 +7 +6 +5 +4 +3 +2 +[(anterier tooth region)
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. e male O female . . . Fig. 8. PTV +10 +9 +8 +7 +6 +5 +4 +3 +2 +1 30 l 40 32 [ 11 F 40 [ 50 50 [ 60 60 1 70 Age 32 32 32 32 32 32 32 32 32 32 32 32 37 3711[1 lillli[111
[3 17 [7 19 13 l3 13 [3 I3 17 l7 [7 ll 13FFFF FFFFFFFFFF
implant sizeThe length of the inserted segment of implants and their PTV at different sites
Comparison of PTV between males and
females for each age group
o
Fig. 7.o
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oo
o
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e male O femaleo
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Fig. 9.32 32 32 32 37 37
il 13 17 19 ll l3
implant sizeComparison of PTV between males and
thJitsicaEL]iL, 20(2) 1994 201
4. The length of the inserted segment of the implant and its PTV were greater for the anterior
tooth region than for the molar region (Fig. 7).
s . Although the number of subjects was small, the PTV was slightly smaller in males than in females in each age group. No aging-related increase in the PTV was noted (Fig. 8).
6 . Even when the PTV was compared between males and females for each size of implants, PTV
was smaller in males than in females (Fig. 9).
Diseussion
According to Kanda et al., the PTV of individual posts is determined by the lock screw locking
conditions2). The PTV is also affected by the morphology of the post's bottom and by the contact
area between the post and the fixture. When the straight post, which fits best the hexagorial fixture, is locked, the PTV is low. The PTV of the screw post is affected by its bottom morphology. Because the PTV measuring post has a tapered bottom, we initially expected that the PTV of this post would be greater than that of the straight post. In practice, however, these two posts has a similar PTV,
probably because the PTV measuring post had been locked more firmly than the straight post. Of the 15 implants used in our department, 13 had a width of 3.2 mm, probably reflecting the
frequent clinical use of 3.2 mm wide implants which fit the jaw of Japanese people well.
Even when the width and the length of the inserted segment of implants were the same, their
PTV varied greatly, This difference probably reflects the different manners of implant insertion.
Bicortically inserted implants seem to have a smaller PTV when compared te the implants inserted
in other fashions, even when their length of the inserted segment are the same.
The analysis of the PTV in relation to the site of insertion revealed that the PTV was greater in the anterior tooth region than in the molar region, probably because the anterior tooth region has
no anatomical structures which can restrict the size of implants. When the PTV of the 32-17F
implant was analyzed in relation to the site of insertion, the PTV was smaller in the anterior tooth region than in the molar region. This result endorses the finding that the PTV of the bicortically
inserted implants had a smaller PTV when compared with implants of the same size and length of
the inserted segment which were inserted in different fashions.
In each age group, the PTV was slightly smaller in males than in females. There was no aging-related increase in PTV.
Although we anticipated that PTV would be affected by postmenopausal osteoporosis in
females, this effect could not be confirmed because sufficient data were not available3).When the PTV was compared between males and females for each size of implants, PTV
tended to be smaller in males than in females, probably because the length of the inserted segment of implants was greater in males.Conclusion
We examined the clinical applicability of the Periotest@ to implants. The following possibilities were suggested :
1 . It seems possible that the Periotest@ allows surgeons to predict the prognosis of implants based on an analysis of the time course of PTV for the same type of implants and to determine the
optimal time to connect the super structure to the implant. In our department, a PTV below +9 is
regarded as indicating the optimal timing of super structure connection.
202 Kanda and Hyo: Clinical Applicability of the Periotest@ for lmplants
should be connected to natural teeth or that the optimal post can be selected based on an analysis of the PTV of natural teeth.
3 . The Periostest@ seems to allow surgeons to check that an implant has been bicortically
inserted. This check seems to be most useful when it is done immediately after implant insertion. In practice, however,the use of the Periostest@ for this check immediately after implant insertion is not possible because the accuracy of drilling differs among different surgeons. The Periotest @
may therefore be used in making such a check at the time of super structure application and in
predicting Iong-term prognosis after super structure application. AIthough the Periotest@ seems to
be clinically applicable to these purposes, it seems indispensable to pay attention to the
re-producibility of the PTV and to standardize the conditions for PTV measurement (e. g., the use of
a standard PTV measuring post in many facilities).
References
1 ) Iijima, T. and Takeda, T. (1990) An observation of chronological change of mobility of ITI implants
with periotest. J. Jpn. Soci. Oral Implantol, 3 : 191-I99.
2) Kanda, S. and Yokota, Y. (1993) An experimental study on a post for periotest measurement in two piece implant. J. Kinki Hokuriku Tiku Sika Igaku Taikai. 45 : 45-4Z
3 ) Murakami, H. and Matsuda, T. (1991) A case report about mobility of implants by periotest. J. Jpn. Soci. Oral Implantol, 4 : 221-229.
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