- Email: [email protected]
Supraeruption of the unopposed maxillary first molar
MICHOLEAKAGE
OF
I’OMPOSI’IE
RESINS
tions. Tenure anti Scotchbond 2 bonding agents were the most effective, followed by Gluma and conventional Scotchbond bonding agents
12. ::I.
REFERENC’FS 2 JL Spanauf .4.1. I )owel and core found Itions using the crmpwite .4daptic Quintessence lnt 197%: 1:49-51. Stahl GJ, 0’Neal F1H. ‘I he complrsi e resin dowel and core .I PROS?‘HE? Ikw l975.:u:642 8. Steele GD. Rcinfo,ced ~vmpw;ite resin foundations lor rndodonticall! treat,ed teeth. .I PIIOSTHETDE:NT 1973;30:816-9. Moll JFP, Howe I)F, ivare (‘IV. Cast gold post and o,re and pink retamed composite resin bases: a comparative study in strength. .I
1% 16.
I'RosTH~':~'l&wr 1978;40:fi42-4.
17.
I 1.
.j.
Rzepka H:;, Abrams FL. Simplifiration of cast and composite resin buildups. .J ~'HOs'rHE:I‘IlENT !982;18:544-6. Ii. Howen HI,. Properties of a silira-re nforced polymer for dental rest~~ra tions. d An] Ilent 4~~0~ 196:3;66:57-61. ‘7. Than AHL. C‘hui .J. Microleakage of xze materials for complete cast
13. 19
20.
I&NT 19;8::iY:l69 7".
!9.Bowen
RI,, Nemuirl K, Rapson JE. Adhesive bondinK of various materials to hard rooth tiskues; forces developing in compostte materials during hardening. .I Am Dent Assoc 1982;106:475-7. 10. 1)avidson (‘I,. de&e A.i, Fe&w A. The compet.ition between the cornposite-dentin hontl strength and the polymerization contraction stress. J Dent Res 19H4:6:i:l:l!~(i-9. 1 I.
Supraeruption D. Campagnon, Laboratoire
of the unopposed DCD!. DU, and A. Woda,
de Physiologie
Orofaciale,
DCD,
Facultb de Chirurgie
t+wall polymerization contraction in dentm cawtw treattad with various bonding agents. &and .I Dent Res 1985;93:216-9. ADA Council on Dental Materials, Instruments. and Equipment. Dentm bonding systems: an update. .I .4m l)enl Asso~ 19X7:1 14:91-5. Jlunksgaard EC’, Asmussen E. Bond strength between dent,in and restorative resins mediated by rmxtures of HKM.4 dnd glut,araldehyde. .J Dent Res 1984;63:1087-9. Robins)n I’B, Moore BK, Sxartz ML,. ‘l’hr elfect 01 microleakage of intrrchanging dentine adhesives in two composite w;ln systrms in vitro. Br Dent J 1988:161:7i-9. swift E.1 Jr A rewew of dentin bonding. (:en Dent 198&:X:396-9. Asmussen E, Munksgaard EC. Adhesirm of’restoralive rebins TOdentin tissues. In: VHnhrrlr G. Smith I)(‘, eds. l’,strrior composite resin dental restoraiive matrrials. LTtrrcht: Peter S,~ulc l’uhlishing (‘0. 1985:2I?“il Brann~trom h,I, Vojinovic 0. Response ot :hc, dental pulp to invasion of bacteria around t,hree tilling materials. J Ilent Child 1976:43:8:3-t). Brannsrdm M. Communication between TOPoral c,sity and the dental pulp asswiated with restorative treatmrnt. Oper I)pnt 1984;9:57-68. Howen RL,. Adhesive bonding of various materials to hard tooth tissues. III. Bonding to dentin improved by pwtreatmtnt and the USC’ of swtace-active comonwner. .J Dent Res l!W:-l4:9O:i-.i. Howen RL.. Adhesive bonding of variuua materials tu hard tooth tissues. 1V. Bonding to dentin. enamel, and flurrapatite improved by the use of ii hurfacr-active monomer. .I Drnt Kes 1?C I-l?Wi 1
maxillary
first molar
DSO, D es Scienceb Dentaire,
Clermont-Ferrand.
France
Supra.eruption of the maxillary first molar in the absence of the mandibular first molar was observed in subjects with both normal and pathologic periodontics. Both the migration of the gingival margin and the increase in the crown height were evaluated in terms of the length of time the antagonist tooth had been missing. Values obtained were compared with those of a reference group with complete normal dentitions. The results show that in the first years following the loss of the opposing tooth, supraeruption is mainly due to growth of the periodontium. Later, or in the ca.se of periodontal pathosis, tooth movement beyond the occlusal plane is due principally to active eruption. (J PROSTHET DENT 1991;66:29-34.)
I
t has often been shown that tooth eruption in man is a continuous process.1-4 ,41sc, several authors have demonstrated in animal experiments continuous periodontal growth that accompanies supraeruption of one or several teeth following the loss of occlusal contacts or orthodontic therapy.5-s However, few reports have been published on supraeruption in humans.”
-a19ssistant, Department
of Prosthetic
Dentistry,
bProfessor, Department of Operative Dentistry. 10/l/28256
THE
JOURNAIL
OF PROSTHETIC
DENTISTRY
This study was concerned with the behavior of the human periodontium following the loss of occlusal contact. Taking advantage of the frequency of mandibular first molar extractions, the supraeruption of the antagonist maxillary first molar was explored. Our analysis was based on the measurements of the visible crown and on the observation of the gingival margin evaluated in relation to that of the two adjacent teeth. To study the evolution of these parameters over a number of years, particular attention was paid to the length of time the antagonist tooth had been missing. The values obtained were compared with those made from complete dentitions. and from dentitions
29
COMPAGNON
Initial
-
I. Use of periodontal
state
indexes in constitution
Tooth missi
11s <
10
c
of
Give (Periodontal
Indexes
Group 2 Healthy periodontium
Group 3 Pathologic periodontium
0 o-1 o-1 0 <2 mm
>1 >I >1 >o >2 mm
ICI y. < tooth missing
< IS y.
pockets
4-
A
In
I
--
P\
+
METHOD Choice of samples In the first. group (the reference group or group l), the selected population was made up of 25 white subjects living in France, between 18 and 50 years of age, with healthy and complete dentitions. The criteria for normality have been described in a previous study.lO A second group (group 2) consisted of 40 white subjects between 18 and 45 years of age who, unlike those of the former group, had an edentulous space in the mandibular
Passive eruption
C# Active eruption + Passive crup;ion
15 y.< Tooth missing
presenting a pathologic periodontium and where the mandibular first molar had been extracted. Examination of the different situations permitted the distinction of several phenomena known as supraeruption, active or passive continuous eruption, and periodontal growth. Supraeruption can be defined as a phenomenon whereby the crown of the tooth erupts beyond the occlusal plane. As will be seen later, supraeruption consists of two components: active eruption and growth of the periodontium. In active eruption, the tooth erupts out of its socket while the periodontium remains stable. The term periodontal growth means growth in an occlusal direction of the periodontal tissues including the alveolar bone, carrying the tooth with it. Since passive eruption is not a true eruption but a regression of the gingiva, it does not lead to supraeruption.
eruption resression)
Cf Active eruution + passive erupiion
/
30
growth = Cte
y.
groups
Periodontal disease index26 Calculus surface indexz7 Plaque index2s Mobility index2s Measurements of periodontal
WODA
-periodontal
Fig. 1. Method of measurement. C, Height of clinical crown; P, difference in height between gingival margin of maxillary first molar and gingival margins of two adjacent teeth.
Table
AND
2. Migration of gingival margin and increase in height of clinical crown in terms of length of time antagonist tooth was missing. In each of four phases (panels 1 to 4) there is an increase in supraeruption. In panel 2, P increases due to periodontal growth and C is constant. In panel 3, P decreases because of passive eruption. This and active eruption lead to an increase in value of C. In panel 4, the same phenomena as in panel 3 but more advanced. Gingival margin is now located beyond its initial position represented in panel 1. Vertical arrows indicate coronal (panel 2) or apical (panels 3 and 4) movement of gingival margin. Fig.
arch allowing supraeruption of only the maxillary first molar. The observed tooth, as well as those adjacent, had an intact crown and a normal periodontium, as shown by the values of the indexes presented in Table I.11-13The date of the extraction, obtained from the patient file, enabled classification of the subjects into four subgroups according to the length of time between the extraction and the study (Table II). The third group (group 3) was made up of 10 subjects with a missing mandibular first molar and with visible signs of periodontal pathosis confirmed by the values of the different indexes, as shown in Table I. The length of time since the extraction was between 5 and 15 years for these subjects.
JULY
1991
VOLUME
66
NUMBER
1
SUPRAERUPTION
Table
II.
Oj
MAXILLARY
ZIRST
AMOLAR
Results of second group in terms of length of time without Time without
III. Comparison occlusal contact
Table
using Student’s
t-test between different
occlusal contact occlusal
contact
(years)
subgroups made up according to length of time without
Pairs of subgroups
P
t = 4.04 p .:: 0.0’) p < 0.001 c ! = 7.3’ t = 8.02 p *:. O.OII1 p < 0.001 --dt’, Degree of f~redml; ns, wnsignificcnt
Method
20 yr (df = 26)
10<<15 yr and 15<<20 yr (df = 20)
t = 5.64 p < 0.001 t = 11.36 p < 0.001
t = ‘3.40 p < 0.0!5 1 = 2.00 1,s
of measurement
For the three g.roups, impressions of the two arches were made using irreversible hydrl,colloids into which dental stone was poured. l4 Two measurements were made of the upper first molars. First, the height of the clinical crown (C) was measured, defined as the c:istance between the limit of the vestibular gingival margin at its most inclined point and the straight line joining the tips of the two vestibular cusps. This value C was obtained using two rulers, the first held against the cusp tips and. the second placed perpendicular to the first, allowing a measurement to be taken (Fig. 1). Second, l;he level of the gingival margin was evaluated by measuring the distance between the most inclined point of the gingival margin and a segment of the line joining equivalent points of the two adjacent teeth. This length was called P A strip of rigid cardboard representing the segml?nt was placed against the cast and the measurement was, made using the same ruler (Fig. 1). For group 1, measurements were taken from both right and left sides.
Data processing The average values obtained from the three groups were called Cl and Pl for group 1 (the reference group), C2 and P2 for group 2 (those with normal periodontium), and C3 and P3 for group 3 (those with pathologic periodontium). The equation P = P2 - Pl expresses the migration of the gingival margin in the absence of an antagonist tooth and
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IO<<15 yr and >20 yr (df = 19) t = 4.19 p < 0.00; t = 4.88 p < 0.00~ __.-..
15<<20 yr and > 20 yr (df = 11) t = 1.71 Llh t = 2.29 p -.c0.05
the equation C = C2 - Cl expresses t,he variation in height of the clinical crown. The averages were calculated for each subgroup representing the length of time the antagonist tooth had been missing. The combined use of P and C, as will be discussed later, permitted an assessment of how much supraeruption was due to active eruption and horn much was due to periodontal growth. The equations P ’ = P3 - Pl and C ’ = C3 - Cl had the same significance in group 3 as P and C in group 2. The Student’s t-test was used to compare the averages obtained from the four subgroups and to compare the averages obtained from groups 2 and 3
RESULTS In the first group, the averages (m t si’\jn) obtained from the left hemiarches (PI = 0.06 + 0.11 mm and C = 6.84 + 0.22 mm, n = 25), and from the right hemiarches (Pl = 0.06 + 0.13 mm and Cl = 6.90 + 0.23 mm, n = 25), did not show any significant difference (t = 0.19, df = 48). Therefore the values from right and left sides were grouped together and the results were: PI = 0.06 + 0.08 mm and Cl = 6.87 + 0.16 mm (n = 50). Table II shows that where there was no pathosis of the periodontium, migration of the periodontal margin (P) took place in an occlusal direction during the early years following extraction and then the direction ofthe migration reversed to apical. The differences observed with respect to the gingival margin limit in the four subgroups taken two
81
COMPAGNON
AND
WODA
r i Tzqyp Periodontal
Active
growth
eruption
Pf
Cf
Passive cruptim
p’,cl’
3iiIGkj
Fig. 3. Schematic definition of supraeruption and passive eruption. Supraeruption equals periodontal growth plus active eruption. Passive eruption alone does not modify the level of cusps in relation to the occlusal plane.
IV. Influence of periodontal pathosis (group 3) and comparison with values from group 2 (supraerupted upper maxillary molar and healthy periodontium)
Table
Group 2 m f s/\/n
P2 = 0.41 * 0.83
C2 = 8.51 rt 1.57
P3 = -1.0 * 0.37
C3 = 11.55 + 0.25
(n = 50) Group 3
m + s/\/n (n = 10) Comparison
(betweengroups
t = 4.556
t = 5.941
p < 0.001
p < 0.001
2 and 3)* (df = 58) *Comparison limeters.
was made using Student’s
t-test and values are given in mil-
by two were significant or highly significant, except for a single pair (Table III). The height of the clinical crown increased with the length of time the antagonist tooth had been missing (Table III). The comparison between the different subgroups showed highly significant differences in four subjects and a nonsignificant difference in one (Table III). Finally, Table IV shows that where a pathologic condition of the periodontium exists, the apical drift of the gingival margin was pronounced and the height of the clinical crown increased considerably (3 mm). DISCUSSION The results from Tables II and III produced the schematized evolution represented in Fig. 2, which shows that
32
during the period that the antagonist tooth was missing a continuous movement of the cusps beyond the occlusal plane took place. This is a sign of an active phenomenon called supraeruption. Many authors have noted this occurrence in man as well as in animals.5r Q,15,l6 Fig. 2, panel 2 shows that the gingival margin evolves in an occlusal direction in the first years after loss of occlusal contacts (Table II). From the referenced data, it appears that the migration of the gingival margin is a sign of subjacent bone growth and in this study it corresponds to P.** l7 This phenomenon is periodontal growth. In the absence of occlusion for more than 10 years (Fig. 2, panels 3 and 4), the gingival margin not only stopped migrating occlusally, but on the contrary, started moving apically (Table II). This phenomenon exposes the crown and often a part of the root. It does not participate in supraeruption and belongs to passive eruption. Also important to note is that after 10 years without occlusal contacts and despite the absence of periodontal growth, the tooth continues to erupt in an occlusal direction (Table II, and Fig. 2, panels 3 and 4). This phenomenon is called active eruption. From the Results section it can be inferred that the role played by periodontal growth in supraeruption is important during the early stages after loss of occlusal contacts, then becomes less so and, after about 10 years, can be considered negligible. From then on it would seem that only active eruption is responsible for supraeruption. It was seen therefore that the increase in height of the clinical crown results from active eruption (the tooth erupts out of its socket) as well as from passive eruption (the periodontium regresses apically). The above-defined phenomena are schematized in Fig. 3.
JULY
1991
VOLUME
06
NUMBER
1
SIt!PRAER~~PTION
OF MM.\ ;ILLAKY
I‘IRST
MOLAH
If this study leads t ) a better understanding of the cornponents making up s~praeruption, with supraeruption be ing the sum of active: erupticln and periodontal growth. several questions still remain tJ be answered. For example. observation of the first subgroup (0 to 10 years without occlusal contacts) does not permit us to give a precise chronology of the stages )f periodontal growth. which would require a longitudinal study. Furthermore, the pilenomena described in this study are perhaps not entirel! physiologic. Indeed, it should be pointed out that the ,:bserved teeth do not enter into mastication. Histologic s: udies have shown a disorganization and then a degeneration of the periodontal ligament and alveolar bone of noniunctional teeth.“, 1ym7’i Active eruption OI curs either when a tooth has been nonfunctional for a lc’ng time )r as a result of a pathologic periodontium (group 3). It is therefore tempting to conclude that periodont 11growth is more a physiologic phenomenon that is acti .le eruption. Several studies on complete dentitions 2 1 “’- I2 have shown that a generalized and continuous supraeru!,tion exists in man and that, it compensates for #)cclusal Near. For example, using ac reference the inferior alveolar :anal, Whittaker et al.‘” have shown that the occlusal plat:e is maintained despite considerable occlusal wear of the ailatomic crown. It also appears in their n,tudy, as in curs, that the occlusal migration oft he cemen toenamel junction re.,ults from periodontal growth and ac tive eruption. Final11 these authors confirm the findings 01’ other studies that sh jw that t.ne migration of the apices in an occlusal direction 2sless than that of the cementoenamel junction, this diff’erei!ce being due to cementum formation at the apex,’ 1.“I 2 The mechanism ot supraeruption still remains to be determined and, in pat titular, its possible relationship with occlusal wear. Begg, reported that supraeruption occur\ independently of OCIlusal weir, which would explain tht increase in the occlu:.al vertical dimension of modern pop ulations presenting little occlusal wear.23* ‘4 Conversely. rapid wear sould lead to a decrease in the occlusal vertical dimension. If, however, as proposed by Levers anti Darling,2 supraeruption compensates for wear, the occlusal vertical dimension would remain constant. This occurs in Eskimos who often present surprisingly high alveolar ridges as well as an Jmost tc.tal attrition of the crow11.~’ From these reported result,;, it would seem that the de sire to maintain the height 0’ the clinical crown const.ant l;hroughout .2 lifetime is a cultural and not a physiolagil, product.“‘
Clinical
implication
From a clinical point of view, this study emphasizes the importance of periodontal health in minimizing active eruption following ioss of occlusal contact. When the antagonist tooth has been missing for many years, provided that periodontal health has been preserved, supraeruption appears to stop. Wh2:n a pathologic condition of the peri-
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I>ENTISTRY
c)dontium sets in, the situation ot I nc nonfunctional tooth is aggralrated by l;he phenomenon cf p:;ssib,r eruption and the acceleration Iof act& erupt,ion 51 )ree>ver, this study raises the question of the particul~tr clinical situation in which antagonist teeth are not in contact in the intercuspal position. whether there is contact in ecccentric excursion ,,r not. X further study 1s necessary t ) determine which forces in rhis case inhibit periodontal _ur,owthand!or active erupt ior;,
CONCLUSION Supraeruption of a tooth following the ~CJSS of antagonist ccInt,act is shown by the movement ofthe crown beyond the occlusal plane. This phenomenon can r)e divided into periodontal growth on the one hand :md active eruption on the other. With a normal dentit,ion. periodontal growth seems to be liberated b> the loss of occlusal contacts but only takes place during t,he early years following the extraction. Later, when the hypofunctioning continues, supraeruption is t:hiefly the result ol’act ive eruption. In the case of’ an inflamed periodontium, supraeruption is more prorlounc,ed and is mainly due to active eruption.
REFEREPiCEP
COMPAGNONANDWODA
18. Stallard RE. The effect of occlusal alterations on collagen formation within the periodontium. Periodontics 1964;2:49-52. 19. Cohn SA. Disuse atrophy of the periodontium in mice following partial loss of function. Arch Oral Biol 1966;11:95-105. 20. Levy GG, Mailland ML. Etude quantitative des effects de l’hypofonction occlusale sur la largeur desmodontale et la resorption osteoclastique chez le rat. J Biol Buccale 1980;8:17-31. 21. Berry DC, Poole DFG. Attrition: possible mechanisms of compensation. J Oral Rehabil 1976;3:201-6. 22. Whittaker DK, Parker JH, Jenkins C. Tooth attrition and continuing eruption in a Romano-British population. Arch Oral Biol 1982;27: 405-g. 23. Tallgreen A. Changes in adult face height due to ageing, wear and loss of teeth and prosthetic treatment. Acta Odontol Stand 1957;15(suppl 24:1-122. 24. Thompson JL, Kendrick GS. Changes in the vertical dimensions of the human male skull during the third and fourth decades of life. Anat Ret 1964:150:209-14.
A crown
for clinically
25. Cran JA. Notes on the teeth and gingivae of Central Australian aborigines. Aust Dent J 1957;2:277-82. 26. Ramfjord JP. Indices for prevalence and incidence of periodontal disease. J Periodontol 1959;30:51-9. 27. Ennever J, Sturzenberger CP, Radike AW. Calculus surface index for scoring. Clinical calculus studies. J Periodontol 1961;32:54-7. 28. Loe H. The gingival index, the plaque index, and the retention index systems. J Periodontol 1967;38:610-6. 29. Muhlemann HR. Periodontometry: a method for measuring tooth mobility. Oral Surg 1951;4:1220. Reprint requests to: PROF. A. WODA FACULT~~ DE CHIRURGIE DENTAIRE 11 BD CHARLES DE GAULLE 63000 CLERMONT-FERRAND FRANCE
investigating
microleakage
D. A. Felton, DDS, MS,B S. C. Bayne, MS, PhD,b B. E. Kanoy, and D. Zapaterod University
of North
Carolina,
School of Dentistry,
DDS,C
Chapel Hill, N.C.
This investigation evaluated a cast crown with an access port for in vivo microleakage studies. Fifteen complete cast crowns containing an access port in the facial surface were cast. The gingival margins of the crowns were modified to test the sealing ability of the access port. Each casting was thermocycled 750 times at 5’ to 60’ C over a 24-hour period. Air pressure of 90 psi followed by 28 mm Hg vacuum was applied for 1 hour each during immersion of the devices in silver nitrate solution. Castings were embedded in acrylic resin and sectioned with a diamond saw through the sealing device. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed no leakage with the 13 test devices and 100% leakage with the controls. The device should be effective for use in human subjects. (J PROSTHET DENT 1991;66:34-8.)
M.
lcroleakage associated with various temporary and permanent restorations has been well documented.lm6 Numerous studies have demonstrated that bacteria and bacterial by-products around dental restorations can have detrimental effects on pulpal tissues.7-14 Only recently, however, has the significance of microleakage below complete-coverage restorations been considered. Studies of microleakage under cemented cast crowns have been limited to a few in vitro investigations. Mondelli et a1.15evaluated the ability of cavity liners and varnishes
This investigation was supported in part by NIH/NIDR grant No. RR05333. aAssistant Professor, Department of Prosthodontics. bAssociate Professor and Head, Section of Biomaterials, Department of Operative Dentistry. cClinical Associate Professor and Acting Chairman, Department of Prosthodontics. dSenior Predoctoral dental student.
10/l/25874
34
to seal the margins of complete crowns against microleakage. They reported that two coats of copal varnish applied to the preparation margins significantly reduced microleakage. However, more recent findings by Pashley et a1.16demonstrated that copal varnishes do little to seal the opening of dentinal tubules or to prevent fluid flow both into and out of the pulp through the permeable dentin. Tjan et a1.17evaluated the effect of thermocycling on microleakage at the margins of cemented cast crowns. All of the specimens exhibited microleakage. Similar findings were reported by Kawamura et al.18 for crowns cemented with zinc phosphate, polycarboxylate, or glass ionomer luting agents. Larsen and Jensenlg compared microleakage of crowns cemented on prepared teeth with microleakage of crowns on teeth with amalgam or composite resin foundations. They found minimal microleakage with previously unrestored teeth, statistically more microleakage with amalgam foundations, and the greatest degree of microleakage with composite resin foundations. They suggested that differ-
JULYlBBl
VOLUME66
NUMBER1
OF
I’OMPOSI’IE
RESINS
tions. Tenure anti Scotchbond 2 bonding agents were the most effective, followed by Gluma and conventional Scotchbond bonding agents
12. ::I.
REFERENC’FS 2 JL Spanauf .4.1. I )owel and core found Itions using the crmpwite .4daptic Quintessence lnt 197%: 1:49-51. Stahl GJ, 0’Neal F1H. ‘I he complrsi e resin dowel and core .I PROS?‘HE? Ikw l975.:u:642 8. Steele GD. Rcinfo,ced ~vmpw;ite resin foundations lor rndodonticall! treat,ed teeth. .I PIIOSTHETDE:NT 1973;30:816-9. Moll JFP, Howe I)F, ivare (‘IV. Cast gold post and o,re and pink retamed composite resin bases: a comparative study in strength. .I
1% 16.
I'RosTH~':~'l&wr 1978;40:fi42-4.
17.
I 1.
.j.
Rzepka H:;, Abrams FL. Simplifiration of cast and composite resin buildups. .J ~'HOs'rHE:I‘IlENT !982;18:544-6. Ii. Howen HI,. Properties of a silira-re nforced polymer for dental rest~~ra tions. d An] Ilent 4~~0~ 196:3;66:57-61. ‘7. Than AHL. C‘hui .J. Microleakage of xze materials for complete cast
13. 19
20.
I&NT 19;8::iY:l69 7".
!9.Bowen
RI,, Nemuirl K, Rapson JE. Adhesive bondinK of various materials to hard rooth tiskues; forces developing in compostte materials during hardening. .I Am Dent Assoc 1982;106:475-7. 10. 1)avidson (‘I,. de&e A.i, Fe&w A. The compet.ition between the cornposite-dentin hontl strength and the polymerization contraction stress. J Dent Res 19H4:6:i:l:l!~(i-9. 1 I.
Supraeruption D. Campagnon, Laboratoire
of the unopposed DCD!. DU, and A. Woda,
de Physiologie
Orofaciale,
DCD,
Facultb de Chirurgie
t+wall polymerization contraction in dentm cawtw treattad with various bonding agents. &and .I Dent Res 1985;93:216-9. ADA Council on Dental Materials, Instruments. and Equipment. Dentm bonding systems: an update. .I .4m l)enl Asso~ 19X7:1 14:91-5. Jlunksgaard EC’, Asmussen E. Bond strength between dent,in and restorative resins mediated by rmxtures of HKM.4 dnd glut,araldehyde. .J Dent Res 1984;63:1087-9. Robins)n I’B, Moore BK, Sxartz ML,. ‘l’hr elfect 01 microleakage of intrrchanging dentine adhesives in two composite w;ln systrms in vitro. Br Dent J 1988:161:7i-9. swift E.1 Jr A rewew of dentin bonding. (:en Dent 198&:X:396-9. Asmussen E, Munksgaard EC. Adhesirm of’restoralive rebins TOdentin tissues. In: VHnhrrlr G. Smith I)(‘, eds. l’,strrior composite resin dental restoraiive matrrials. LTtrrcht: Peter S,~ulc l’uhlishing (‘0. 1985:2I?“il Brann~trom h,I, Vojinovic 0. Response ot :hc, dental pulp to invasion of bacteria around t,hree tilling materials. J Ilent Child 1976:43:8:3-t). Brannsrdm M. Communication between TOPoral c,sity and the dental pulp asswiated with restorative treatmrnt. Oper I)pnt 1984;9:57-68. Howen RL,. Adhesive bonding of various materials to hard tooth tissues. III. Bonding to dentin improved by pwtreatmtnt and the USC’ of swtace-active comonwner. .J Dent Res l!W:-l4:9O:i-.i. Howen RL.. Adhesive bonding of variuua materials tu hard tooth tissues. 1V. Bonding to dentin. enamel, and flurrapatite improved by the use of ii hurfacr-active monomer. .I Drnt Kes 1?C I-l?Wi 1
maxillary
first molar
DSO, D es Scienceb Dentaire,
Clermont-Ferrand.
France
Supra.eruption of the maxillary first molar in the absence of the mandibular first molar was observed in subjects with both normal and pathologic periodontics. Both the migration of the gingival margin and the increase in the crown height were evaluated in terms of the length of time the antagonist tooth had been missing. Values obtained were compared with those of a reference group with complete normal dentitions. The results show that in the first years following the loss of the opposing tooth, supraeruption is mainly due to growth of the periodontium. Later, or in the ca.se of periodontal pathosis, tooth movement beyond the occlusal plane is due principally to active eruption. (J PROSTHET DENT 1991;66:29-34.)
I
t has often been shown that tooth eruption in man is a continuous process.1-4 ,41sc, several authors have demonstrated in animal experiments continuous periodontal growth that accompanies supraeruption of one or several teeth following the loss of occlusal contacts or orthodontic therapy.5-s However, few reports have been published on supraeruption in humans.”
-a19ssistant, Department
of Prosthetic
Dentistry,
bProfessor, Department of Operative Dentistry. 10/l/28256
THE
JOURNAIL
OF PROSTHETIC
DENTISTRY
This study was concerned with the behavior of the human periodontium following the loss of occlusal contact. Taking advantage of the frequency of mandibular first molar extractions, the supraeruption of the antagonist maxillary first molar was explored. Our analysis was based on the measurements of the visible crown and on the observation of the gingival margin evaluated in relation to that of the two adjacent teeth. To study the evolution of these parameters over a number of years, particular attention was paid to the length of time the antagonist tooth had been missing. The values obtained were compared with those made from complete dentitions. and from dentitions
29
COMPAGNON
Initial
-
I. Use of periodontal
state
indexes in constitution
Tooth missi
11s <
10
c
of
Give (Periodontal
Indexes
Group 2 Healthy periodontium
Group 3 Pathologic periodontium
0 o-1 o-1 0 <2 mm
>1 >I >1 >o >2 mm
ICI y. < tooth missing
< IS y.
pockets
4-
A
In
I
--
P\
+
METHOD Choice of samples In the first. group (the reference group or group l), the selected population was made up of 25 white subjects living in France, between 18 and 50 years of age, with healthy and complete dentitions. The criteria for normality have been described in a previous study.lO A second group (group 2) consisted of 40 white subjects between 18 and 45 years of age who, unlike those of the former group, had an edentulous space in the mandibular
Passive eruption
C# Active eruption + Passive crup;ion
15 y.< Tooth missing
presenting a pathologic periodontium and where the mandibular first molar had been extracted. Examination of the different situations permitted the distinction of several phenomena known as supraeruption, active or passive continuous eruption, and periodontal growth. Supraeruption can be defined as a phenomenon whereby the crown of the tooth erupts beyond the occlusal plane. As will be seen later, supraeruption consists of two components: active eruption and growth of the periodontium. In active eruption, the tooth erupts out of its socket while the periodontium remains stable. The term periodontal growth means growth in an occlusal direction of the periodontal tissues including the alveolar bone, carrying the tooth with it. Since passive eruption is not a true eruption but a regression of the gingiva, it does not lead to supraeruption.
eruption resression)
Cf Active eruution + passive erupiion
/
30
growth = Cte
y.
groups
Periodontal disease index26 Calculus surface indexz7 Plaque index2s Mobility index2s Measurements of periodontal
WODA
-periodontal
Fig. 1. Method of measurement. C, Height of clinical crown; P, difference in height between gingival margin of maxillary first molar and gingival margins of two adjacent teeth.
Table
AND
2. Migration of gingival margin and increase in height of clinical crown in terms of length of time antagonist tooth was missing. In each of four phases (panels 1 to 4) there is an increase in supraeruption. In panel 2, P increases due to periodontal growth and C is constant. In panel 3, P decreases because of passive eruption. This and active eruption lead to an increase in value of C. In panel 4, the same phenomena as in panel 3 but more advanced. Gingival margin is now located beyond its initial position represented in panel 1. Vertical arrows indicate coronal (panel 2) or apical (panels 3 and 4) movement of gingival margin. Fig.
arch allowing supraeruption of only the maxillary first molar. The observed tooth, as well as those adjacent, had an intact crown and a normal periodontium, as shown by the values of the indexes presented in Table I.11-13The date of the extraction, obtained from the patient file, enabled classification of the subjects into four subgroups according to the length of time between the extraction and the study (Table II). The third group (group 3) was made up of 10 subjects with a missing mandibular first molar and with visible signs of periodontal pathosis confirmed by the values of the different indexes, as shown in Table I. The length of time since the extraction was between 5 and 15 years for these subjects.
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Table
II.
Oj
MAXILLARY
ZIRST
AMOLAR
Results of second group in terms of length of time without Time without
III. Comparison occlusal contact
Table
using Student’s
t-test between different
occlusal contact occlusal
contact
(years)
subgroups made up according to length of time without
Pairs of subgroups
P
t = 4.04 p .:: 0.0’) p < 0.001 c ! = 7.3’ t = 8.02 p *:. O.OII1 p < 0.001 --dt’, Degree of f~redml; ns, wnsignificcnt
Method
10<<15 yr and 15<<20 yr (df = 20)
t = 5.64 p < 0.001 t = 11.36 p < 0.001
t = ‘3.40 p < 0.0!5 1 = 2.00 1,s
of measurement
For the three g.roups, impressions of the two arches were made using irreversible hydrl,colloids into which dental stone was poured. l4 Two measurements were made of the upper first molars. First, the height of the clinical crown (C) was measured, defined as the c:istance between the limit of the vestibular gingival margin at its most inclined point and the straight line joining the tips of the two vestibular cusps. This value C was obtained using two rulers, the first held against the cusp tips and. the second placed perpendicular to the first, allowing a measurement to be taken (Fig. 1). Second, l;he level of the gingival margin was evaluated by measuring the distance between the most inclined point of the gingival margin and a segment of the line joining equivalent points of the two adjacent teeth. This length was called P A strip of rigid cardboard representing the segml?nt was placed against the cast and the measurement was, made using the same ruler (Fig. 1). For group 1, measurements were taken from both right and left sides.
Data processing The average values obtained from the three groups were called Cl and Pl for group 1 (the reference group), C2 and P2 for group 2 (those with normal periodontium), and C3 and P3 for group 3 (those with pathologic periodontium). The equation P = P2 - Pl expresses the migration of the gingival margin in the absence of an antagonist tooth and
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DIZNTISTRY
IO<<15 yr and >20 yr (df = 19) t = 4.19 p < 0.00; t = 4.88 p < 0.00~ __.-..
15<<20 yr and > 20 yr (df = 11) t = 1.71 Llh t = 2.29 p -.c0.05
the equation C = C2 - Cl expresses t,he variation in height of the clinical crown. The averages were calculated for each subgroup representing the length of time the antagonist tooth had been missing. The combined use of P and C, as will be discussed later, permitted an assessment of how much supraeruption was due to active eruption and horn much was due to periodontal growth. The equations P ’ = P3 - Pl and C ’ = C3 - Cl had the same significance in group 3 as P and C in group 2. The Student’s t-test was used to compare the averages obtained from the four subgroups and to compare the averages obtained from groups 2 and 3
RESULTS In the first group, the averages (m t si’\jn) obtained from the left hemiarches (PI = 0.06 + 0.11 mm and C = 6.84 + 0.22 mm, n = 25), and from the right hemiarches (Pl = 0.06 + 0.13 mm and Cl = 6.90 + 0.23 mm, n = 25), did not show any significant difference (t = 0.19, df = 48). Therefore the values from right and left sides were grouped together and the results were: PI = 0.06 + 0.08 mm and Cl = 6.87 + 0.16 mm (n = 50). Table II shows that where there was no pathosis of the periodontium, migration of the periodontal margin (P) took place in an occlusal direction during the early years following extraction and then the direction ofthe migration reversed to apical. The differences observed with respect to the gingival margin limit in the four subgroups taken two
81
COMPAGNON
AND
WODA
r i Tzqyp Periodontal
Active
growth
eruption
Pf
Cf
Passive cruptim
p’,cl’
3iiIGkj
Fig. 3. Schematic definition of supraeruption and passive eruption. Supraeruption equals periodontal growth plus active eruption. Passive eruption alone does not modify the level of cusps in relation to the occlusal plane.
IV. Influence of periodontal pathosis (group 3) and comparison with values from group 2 (supraerupted upper maxillary molar and healthy periodontium)
Table
Group 2 m f s/\/n
P2 = 0.41 * 0.83
C2 = 8.51 rt 1.57
P3 = -1.0 * 0.37
C3 = 11.55 + 0.25
(n = 50) Group 3
m + s/\/n (n = 10) Comparison
(betweengroups
t = 4.556
t = 5.941
p < 0.001
p < 0.001
2 and 3)* (df = 58) *Comparison limeters.
was made using Student’s
t-test and values are given in mil-
by two were significant or highly significant, except for a single pair (Table III). The height of the clinical crown increased with the length of time the antagonist tooth had been missing (Table III). The comparison between the different subgroups showed highly significant differences in four subjects and a nonsignificant difference in one (Table III). Finally, Table IV shows that where a pathologic condition of the periodontium exists, the apical drift of the gingival margin was pronounced and the height of the clinical crown increased considerably (3 mm). DISCUSSION The results from Tables II and III produced the schematized evolution represented in Fig. 2, which shows that
32
during the period that the antagonist tooth was missing a continuous movement of the cusps beyond the occlusal plane took place. This is a sign of an active phenomenon called supraeruption. Many authors have noted this occurrence in man as well as in animals.5r Q,15,l6 Fig. 2, panel 2 shows that the gingival margin evolves in an occlusal direction in the first years after loss of occlusal contacts (Table II). From the referenced data, it appears that the migration of the gingival margin is a sign of subjacent bone growth and in this study it corresponds to P.** l7 This phenomenon is periodontal growth. In the absence of occlusion for more than 10 years (Fig. 2, panels 3 and 4), the gingival margin not only stopped migrating occlusally, but on the contrary, started moving apically (Table II). This phenomenon exposes the crown and often a part of the root. It does not participate in supraeruption and belongs to passive eruption. Also important to note is that after 10 years without occlusal contacts and despite the absence of periodontal growth, the tooth continues to erupt in an occlusal direction (Table II, and Fig. 2, panels 3 and 4). This phenomenon is called active eruption. From the Results section it can be inferred that the role played by periodontal growth in supraeruption is important during the early stages after loss of occlusal contacts, then becomes less so and, after about 10 years, can be considered negligible. From then on it would seem that only active eruption is responsible for supraeruption. It was seen therefore that the increase in height of the clinical crown results from active eruption (the tooth erupts out of its socket) as well as from passive eruption (the periodontium regresses apically). The above-defined phenomena are schematized in Fig. 3.
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1991
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SIt!PRAER~~PTION
OF MM.\ ;ILLAKY
I‘IRST
MOLAH
If this study leads t ) a better understanding of the cornponents making up s~praeruption, with supraeruption be ing the sum of active: erupticln and periodontal growth. several questions still remain tJ be answered. For example. observation of the first subgroup (0 to 10 years without occlusal contacts) does not permit us to give a precise chronology of the stages )f periodontal growth. which would require a longitudinal study. Furthermore, the pilenomena described in this study are perhaps not entirel! physiologic. Indeed, it should be pointed out that the ,:bserved teeth do not enter into mastication. Histologic s: udies have shown a disorganization and then a degeneration of the periodontal ligament and alveolar bone of noniunctional teeth.“, 1ym7’i Active eruption OI curs either when a tooth has been nonfunctional for a lc’ng time )r as a result of a pathologic periodontium (group 3). It is therefore tempting to conclude that periodont 11growth is more a physiologic phenomenon that is acti .le eruption. Several studies on complete dentitions 2 1 “’- I2 have shown that a generalized and continuous supraeru!,tion exists in man and that, it compensates for #)cclusal Near. For example, using ac reference the inferior alveolar :anal, Whittaker et al.‘” have shown that the occlusal plat:e is maintained despite considerable occlusal wear of the ailatomic crown. It also appears in their n,tudy, as in curs, that the occlusal migration oft he cemen toenamel junction re.,ults from periodontal growth and ac tive eruption. Final11 these authors confirm the findings 01’ other studies that sh jw that t.ne migration of the apices in an occlusal direction 2sless than that of the cementoenamel junction, this diff’erei!ce being due to cementum formation at the apex,’ 1.“I 2 The mechanism ot supraeruption still remains to be determined and, in pat titular, its possible relationship with occlusal wear. Begg, reported that supraeruption occur\ independently of OCIlusal weir, which would explain tht increase in the occlu:.al vertical dimension of modern pop ulations presenting little occlusal wear.23* ‘4 Conversely. rapid wear sould lead to a decrease in the occlusal vertical dimension. If, however, as proposed by Levers anti Darling,2 supraeruption compensates for wear, the occlusal vertical dimension would remain constant. This occurs in Eskimos who often present surprisingly high alveolar ridges as well as an Jmost tc.tal attrition of the crow11.~’ From these reported result,;, it would seem that the de sire to maintain the height 0’ the clinical crown const.ant l;hroughout .2 lifetime is a cultural and not a physiolagil, product.“‘
Clinical
implication
From a clinical point of view, this study emphasizes the importance of periodontal health in minimizing active eruption following ioss of occlusal contact. When the antagonist tooth has been missing for many years, provided that periodontal health has been preserved, supraeruption appears to stop. Wh2:n a pathologic condition of the peri-
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JOURNAI,
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PROqTHETIC
I>ENTISTRY
c)dontium sets in, the situation ot I nc nonfunctional tooth is aggralrated by l;he phenomenon cf p:;ssib,r eruption and the acceleration Iof act& erupt,ion 51 )ree>ver, this study raises the question of the particul~tr clinical situation in which antagonist teeth are not in contact in the intercuspal position. whether there is contact in ecccentric excursion ,,r not. X further study 1s necessary t ) determine which forces in rhis case inhibit periodontal _ur,owthand!or active erupt ior;,
CONCLUSION Supraeruption of a tooth following the ~CJSS of antagonist ccInt,act is shown by the movement ofthe crown beyond the occlusal plane. This phenomenon can r)e divided into periodontal growth on the one hand :md active eruption on the other. With a normal dentit,ion. periodontal growth seems to be liberated b> the loss of occlusal contacts but only takes place during t,he early years following the extraction. Later, when the hypofunctioning continues, supraeruption is t:hiefly the result ol’act ive eruption. In the case of’ an inflamed periodontium, supraeruption is more prorlounc,ed and is mainly due to active eruption.
REFEREPiCEP
COMPAGNONANDWODA
18. Stallard RE. The effect of occlusal alterations on collagen formation within the periodontium. Periodontics 1964;2:49-52. 19. Cohn SA. Disuse atrophy of the periodontium in mice following partial loss of function. Arch Oral Biol 1966;11:95-105. 20. Levy GG, Mailland ML. Etude quantitative des effects de l’hypofonction occlusale sur la largeur desmodontale et la resorption osteoclastique chez le rat. J Biol Buccale 1980;8:17-31. 21. Berry DC, Poole DFG. Attrition: possible mechanisms of compensation. J Oral Rehabil 1976;3:201-6. 22. Whittaker DK, Parker JH, Jenkins C. Tooth attrition and continuing eruption in a Romano-British population. Arch Oral Biol 1982;27: 405-g. 23. Tallgreen A. Changes in adult face height due to ageing, wear and loss of teeth and prosthetic treatment. Acta Odontol Stand 1957;15(suppl 24:1-122. 24. Thompson JL, Kendrick GS. Changes in the vertical dimensions of the human male skull during the third and fourth decades of life. Anat Ret 1964:150:209-14.
A crown
for clinically
25. Cran JA. Notes on the teeth and gingivae of Central Australian aborigines. Aust Dent J 1957;2:277-82. 26. Ramfjord JP. Indices for prevalence and incidence of periodontal disease. J Periodontol 1959;30:51-9. 27. Ennever J, Sturzenberger CP, Radike AW. Calculus surface index for scoring. Clinical calculus studies. J Periodontol 1961;32:54-7. 28. Loe H. The gingival index, the plaque index, and the retention index systems. J Periodontol 1967;38:610-6. 29. Muhlemann HR. Periodontometry: a method for measuring tooth mobility. Oral Surg 1951;4:1220. Reprint requests to: PROF. A. WODA FACULT~~ DE CHIRURGIE DENTAIRE 11 BD CHARLES DE GAULLE 63000 CLERMONT-FERRAND FRANCE
investigating
microleakage
D. A. Felton, DDS, MS,B S. C. Bayne, MS, PhD,b B. E. Kanoy, and D. Zapaterod University
of North
Carolina,
School of Dentistry,
DDS,C
Chapel Hill, N.C.
This investigation evaluated a cast crown with an access port for in vivo microleakage studies. Fifteen complete cast crowns containing an access port in the facial surface were cast. The gingival margins of the crowns were modified to test the sealing ability of the access port. Each casting was thermocycled 750 times at 5’ to 60’ C over a 24-hour period. Air pressure of 90 psi followed by 28 mm Hg vacuum was applied for 1 hour each during immersion of the devices in silver nitrate solution. Castings were embedded in acrylic resin and sectioned with a diamond saw through the sealing device. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed no leakage with the 13 test devices and 100% leakage with the controls. The device should be effective for use in human subjects. (J PROSTHET DENT 1991;66:34-8.)
M.
lcroleakage associated with various temporary and permanent restorations has been well documented.lm6 Numerous studies have demonstrated that bacteria and bacterial by-products around dental restorations can have detrimental effects on pulpal tissues.7-14 Only recently, however, has the significance of microleakage below complete-coverage restorations been considered. Studies of microleakage under cemented cast crowns have been limited to a few in vitro investigations. Mondelli et a1.15evaluated the ability of cavity liners and varnishes
This investigation was supported in part by NIH/NIDR grant No. RR05333. aAssistant Professor, Department of Prosthodontics. bAssociate Professor and Head, Section of Biomaterials, Department of Operative Dentistry. cClinical Associate Professor and Acting Chairman, Department of Prosthodontics. dSenior Predoctoral dental student.
10/l/25874
34
to seal the margins of complete crowns against microleakage. They reported that two coats of copal varnish applied to the preparation margins significantly reduced microleakage. However, more recent findings by Pashley et a1.16demonstrated that copal varnishes do little to seal the opening of dentinal tubules or to prevent fluid flow both into and out of the pulp through the permeable dentin. Tjan et a1.17evaluated the effect of thermocycling on microleakage at the margins of cemented cast crowns. All of the specimens exhibited microleakage. Similar findings were reported by Kawamura et al.18 for crowns cemented with zinc phosphate, polycarboxylate, or glass ionomer luting agents. Larsen and Jensenlg compared microleakage of crowns cemented on prepared teeth with microleakage of crowns on teeth with amalgam or composite resin foundations. They found minimal microleakage with previously unrestored teeth, statistically more microleakage with amalgam foundations, and the greatest degree of microleakage with composite resin foundations. They suggested that differ-
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