Download 72-77 Ask an Expert - Vela y Lasagabaster

Ask an Expert
T H I N G S
Y O U
W A N T
T O
K N O W
Repositioning of the Gingival Margin by
Extrusion and Intrusion
In one of my recent cases, I used active intrusion of two maxillary central
incisors to reposition their gingival margins in an apical direction. These teeth
were then restored with porcelain laminate veneers, and the final result was
esthetically improved with regard to both clinical crown lengths and labial marginal gingival levels. This case indicates to me that orthodontic treatment can
contribute to results that are difficult, if not impossible, to obtain by other
means of esthetic dentistry. Furthermore, a recent AJODO article1 from a team
in Hong Kong demonstrated that the labial gingival margin of a maxillary canine
substituting for a congenitally missing lateral incisor was moved almost 9 mm
incisally by means of orthodontic extrusion. These cases imply that the potential
of an orthodontist in improving gingival levels may often be overlooked by other
dentists. As far as I know, most research on orthodontic intrusion and extrusion
of teeth has dealt with tissue reactions other than changes of the gingival levels. What is actually the present knowledge or state-of-the-art when it comes to
changes in crown lengths and repositioning of gingival levels associated with
tooth movements in the vertical plane? —Arni Thordarson, Reykjavik, Iceland
BJÖRN U. ZACHRISSON, OSLO, NORWAY
Evaluating crown length discrepancies
Ideally, maxillary central incisors are equal in length and the lateral incisors are
slightly shorter. The gingival margin of the lateral incisor is located more
incisally than on the central incisor. The maxillary canines are about the same
length as the central incisors, and their cusp tips are located at the same level
as the incisal edges of the centrals. The gingival margins of the canines are at
the same height as those of the central incisors.2
If the difference in crown length and gingival contour of the maxillary
incisors is substantial, the esthetic appearance can be unsatisfactory, depending on the tooth display on smiling. The discrepancy in crown length is accentuated (1) if a central incisor is abraded or fractured and allowed to erupt, (2)
when maxillary canines are substituted for lateral incisors3 or (3) when lateral
incisors are moved orthodontically to replace central incisors.4 If both central
incisors are shorter than the lateral incisors, like in your case (Fig 1a), your
treatment strategy to simultaneously intrude both central incisors to reposition
their gingival margins apically (Fig 1b) and create space for porcelain laminate
veneers or crowns (Fig 1c) is the optimal method.
Extrusion
Selective orthodontic extrusion of one, or more, teeth is easy to achieve from a
biomechanical point of view. Biologically, such movements closely resemble
72
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
a
c
b
Fig 1 Frontal view of female patient, 28 years of age, with a Class II, Division 2 malocclusion, in whom the pretreatment labial
gingival levels of both maxillary central incisors were located more incisally than the gingival levels of the lateral incisors and
canines (a). The clinical crowns of the central incisors were short, due to abrasive wear and supraeruption. During the orthodontic
treatment, the central incisors were actively intruded to normalize the gingival levels of the six anterior teeth (b). Two porcelain
laminate veneers (courtesy of Dr Sverker Toreskog, Göteborg, Sweden) were used for crown lengthening (c). (Orthodontic treatment by Dr Arni Thordarson, Reykjavik, Iceland)
the natural eruptive tooth movement. The stretching of the gingival and most coronal periodontal ligament fibers leads to coronal migration of the gingiva and attachment apparatus. To allow forced eruption without supraocclusion and occlusal interferences, the crown
of the tooth will need to be continuously shortened by grinding (Figs 2 and 3). Since the
vertical dimension of the alveolar process and gingiva around the extruded tooth is
increased, whereas the osseous and gingival structure of neighboring teeth remain
unchanged, 5 a change in the contour of the hard and soft tissues surrounding the
extruded tooth will be observed (Figs 2 and 3). Orthodontic extrusion of a “hopeless” tooth
that needs to be extracted is thus an excellent method for improvement of the marginal
bone and gingival levels associated with the surgical placement of implants.
The effect of orthodontic extrusion on the periodontal tissues has been assessed in
both clinical studies and animal experiments. Early studies6-9 documented that extrusion
results in (1) bone apposition at the alveolar crest as well as at the apex of the relocated
tooth, (2) a normal relationship with the cemento-enamel junction (CEJ), and (3) an
increase of the width of the zone of attached gingiva (ie, distance from free gingival margin
to mucogingival line minus sulcus depth10). These findings demonstrate that the marginal
periodontium migrates with the erupting tooth and that the mucogingival junction remains
stable. If a coronal displacement of the gingiva and supracrestal connective tissue is not
aimed at, and crestal bone apposition is undesired, the forced eruption should be combined with fiberotomy procedures repeated at least every 2 weeks.5,11
The movement of the labial gingival margins with extrusion (3, 6, and 9 mm) of maxillary incisors was studied clinically and histologically in monkeys by Kajiyama, et al.12 Two
tattoo marks were placed to indicate the vertical positions of the clinical sulcus bottom
and the mucogingival junction. The results showed that the CEJ followed the extruded
teeth closely, and the tattoo mark representing the sulcus bottom followed the teeth about
90%. The labial gingival margins followed the teeth about 80%, as the clinical crown length
increased with about 20%. The sulcus depth was slightly reduced on the extruded teeth,
which could be a temporary reaction. The distance between the two tattoo marks
increased; that is, the width of the attached gingiva increased.
73
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
a
c
b
Fig 2 Marked labial gingival recession of the maxillary right lateral and central incisors (arrows) in female patient, 55 years of age
(a). The brackets on these teeth were rebonded in an apical location and the incisal edges were ground to allow forced eruption
without occlusal interferences (b). After 3 months, the gingival levels were more optimal. Four porcelain laminate veneers were
then made for esthetic reasons (courtesy of Dr Roy Samuelsson, Oslo, Norway). Note posttreatment symmetry of gingival levels
of the six anterior maxillary teeth (c).
a
b
d
e
c
Fig 3 Marked labial gingival recession on maxillary right lateral incisor in female
patient, 57 years of age. The exposed root is discolored because of previous endodontic treatment (arrow in a). Bracket on lateral incisor was bonded in an apical location (b).
Incisal (arrow in c) and lingual equilibration (d) was made to avoid occlusal interferences
during the orthodontic extrusion. After 3 months, the gingiva is repositioned incisally
(c). Note amount of grinding (b and c) and that the gingiva did not completely follow the
extrusion (see text for explanation), so there is more dark root exposed posttreatment
(compare b and c). New, more esthetic, restorations were made on the anterior teeth
(courtesy of Dr Roy Samuelsson) after the orthodontic treatment (e and f).
f
Similarly, Berglundh, et al11 observed in experiments with dogs that orthodontic extrusion without adjunctive fiberotomy induced coronal “growth” of the periodontium. Experimental roots were forced to extrude an average distance of 4.5 mm. The probing depths
remained unchanged and the gingival margin receded only by an average of 0.5 mm. This
implies that orthodontic extrusion may change the position of the gingival margin and
bone crest without undue encroachment of the supracrestal attachment apparatus. The
width of the zone of attached gingiva increased, confirming the observations that the marginal periodontium migrates with the erupting tooth, whereas the location of the mucogingival junction remains stable.7,13,14
74
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
a
b
c
d
e
f
Fig 4 Active intrusion á la Kokich2,16 with small archwire bends on either side of supraerupted maxillary right central incisor in
young adult female patient (a to c). These bends produce an interrupted continuous force with rest periods between the activations. After the orthodontic intrusion of the right central incisor and its labial gingiva, a porcelain laminate veneer (courtesy of Dr
Sverker Toreskog) was made to lengthen the clinical crown (d to f) and improve the esthetic result.
Together, these animal studies indicated that although the labial gingiva will generally
follow an orthodontically extruded tooth, it may be prudent for a clinician to predict that
the amount of vertical gain in gingival level will be about 80% of the distance that a tooth
is extruded (see Figs 2 and 3). There are few clinical studies in humans on orthodontic
extrusion to correct gingival recessions. However, the esthetic improvement in gingival levels in Figs 2 and 3, and in the case report mentioned above,1 is remarkable and should
constitute a piece of information for dentists.
Intrusion
Similar to the case with extrusion, metric and histologic studies have been made after
experimental intrusion (1.5 to 5.5 mm) of incisors in monkeys. According to Murakami, et
al,15 the gingiva moved about 60% of the distance when the teeth were intruded with a
continuous force of 80 to 100 g. The clinical crown shortened and the gingival sulcus
deepened because of an accumulation of gingival tissue, not due to swelling of the gingival margin or migration of the sulcus bottom beyond the CEJ. The distance between the
incisor edge and the sulcus bottom was unchanged. The data were taken right after the
intrusion, so future studies are needed to find out whether the accumulation of gingiva in
the animals is temporary or not.
Kokich, et al16 reported on five cases with either fractured or traumatically avulsed central incisors in which selective intrusion and restorative techniques were used during the
finishing stages of orthodontic treatment to improve the esthetic result. An interrupted,
continuous force with small archwire bends on each side of the tooth to be intruded (Figs
4a and 4b) was used for leveling of gingival margins on supraerupted teeth. The stability of
tooth intrusion is most likely related to the occlusion. If occlusal contact is re-established
after intrusion, the intruded tooth probably will not re-erupt.2
If, due to inadequate oral hygiene measures during the orthodontic treatment or other
reasons, some increased probing pocket depth is found at the time of debonding, the
75
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
A
a
b
c
d
e
f
Fig 5 Traumatic injury case with ankylosed maxillary right central incisor (arrow) in girl, 8 years of age (a). The case was treated by
careful extraction of the ankylosed incisor and mesial movement of all teeth in the maxillary right quadrant. During treatment, the lateral incisor to replace the extracted right central incisor was intruded with interrupted continuous forces to make the gingival level
more similar to that of the left central incisor (b). The canine to replace the lateral incisor was extruded (c) to move the gingival margin incisally. A local gingivectomy was needed to level the gingiva of the “new” right and the intact left central incisors (d). At a later
visit, gingivectomies were also made on the right first premolar to substitute for the canine and on the left lateral incisor. A porcelain
laminate veneer was made on the mesially moved lateral incisor, and the chipped left central incisor edge was restored with a composite resin “corner” (both courtesy of Dr Sverker Toreskog). The final result is an almost natural-looking dentition (e and f).
incisor intrusion may be supplemented with a simple gingivectomy to correct the crown
length discrepancies (Fig 5). A permanent crown length increase corresponding to close to
50% of the original probing depth can be expected when the gingivectomy is made to the
bottom of the pocket in young patients.17 In other words, about half the amount of excised
gingival tissue will regenerate within some months. However, the gingivectomy after the
healing period must not expose the cementum of the tooth, which can lead to tooth sensitivity and an undesirable esthetic result. If inflammation occurs because of a violation of
the biologic width, corrective periodontal surgery with flap procedure and ostectomy/osteoplasty is necessary to complete the repositioning of the gingival margin. The alveolar crest
should generally be positioned at a distance of at least 3 mm from the future crown margin
when prosthetic reconstructions are planned.18 In esthetically critical and visible areas, any
occurrence of gingival recession should be observed for about 6 months before a final prosthetic restoration is inserted.18
The effect on crown lengths and gingival levels by intrusion of pathologically extruded
incisors in adults with severe periodontal tissue breakdown is discussed elsewhere.19,20
Conclusion
The gingiva around a tooth moves along with the tooth in whatever direction the tooth is
moved orthodontically. Through slow extrusion or selective intrusion of the appropriate
teeth and either reduction or restoration of the incisal edges, the gingival contours and
crown lengths of incisors can be made more esthetic. Orthodontic extrusion may be a viable
biologic alternative to gingival grafting in some cases of marked labial recession on
incisors, particularly if they have been treated endodontically.
76
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.
References
1. Chay SH, Rabie ABM. Repositioning of the gingival margin by extrusion. Am J Orthod Dentofacial
Orthop 2002;122:95–102.
2. Kokich VG. Esthetics and anterior tooth position: An orthodontic perspective. Part I: Crown length. J
Esthet Dent 1993;5:19–23.
3. Rosa M, Zachrisson BU. Integrating esthetic dentistry and space closure in patients with missing maxillary lateral incisors. J Clin Orthod 2001;35:221–234.
4. Zachrisson BU. Improving orthodontic results in cases with maxillary incisors missing. Am J Orthod
1978;73:274–289.
5. Kozlovsky A, Tal H, Soldinger M, Straus M. Two different techniques of forced eruption as an aid in the
treatment of severely damaged teeth. J Israel Dent Assoc 1988;6:3–8.
6. Reitan K. Clinical and histologic observations on tooth movement during and after orthodontic treatment. Am J Orthod 1967;53:721–745.
7. Batenhorst KF, Bowers GM, Williams JE Jr. Tissue changes resulting from facial tipping and extrusion
of incisors in monkeys. J Periodontol 1974;45:660–668.
8. Simon JHS, Lythgoe JB, Torabinejad M. Clinical and histologic evaluation of extruded endodontically
treated teeth in dogs. Oral Surg 1980;50:361–371.
9. Van Venroy JR, Yukna RA. Orthodontic extrusion of single teeth affected with advanced periodontal disease. Am J Orthod 1985;87:67–74.
10. Hall WB. The current status of mucogingival problems and their therapy. J Periodont
1981;52:569–575.
11. Berglundh T, Marinello CP, Lindhe J, Thilander B, Liljenberg B. Periodontal tissue reactions to orthodontic extrusion. J Clin Periodontol 1991;18:330–336.
12. Kajiyama K, Murakami T, Yokota S. Gingival reactions after experimentally induced extrusion of the
upper incisors in monkeys. Am J Orthod Dentofacial Orthop 1993;104:36–47.
13. Ainamo J, Talari A. The increase with age of the width of attached gingiva. J Periodont Res
1976;11:182–188.
14. Ainamo A. Influence of age on the location of the maxillary mucogingival junction. J Periodont Res
1978;13:189–193.
15. Murakami T, Yokota S, Takahama Y. Periodontal changes after experimentally induced intrusion of the
upper incisors in Macaca fuscata monkeys. Am J Orthod Dentofacial Orthop 1989;95:115–126.
16. Kokich VG, Nappen DL, Shapiro PA. Gingival contour and clinical crown length: Their effect on the
esthetic appearance of maxillary anterior teeth. Am J Orthod 1984;86:89–94.
17. Monefeldt I, Zachrisson BU. Adjustment of clinical crown height by gingivectomy following orthodontic
space closure. Angle Orthod 1977;47:256–264.
18. Brägger U, Lauchenauer D, Lang NP. Surgical lengthening of the clinical crown. J Clin Periodontol
1992;19:58–63.
19. Zachrisson BU. Orthodontics and periodontics. In: Lindhe J, Karring T, Lang NP (eds). Clinical Periodontology and Implant Dentistry. Copenhagen: Munksgaard 1997;741–793.
20. Cardaropoli D, Re S, Corrente G, Abundo R. Intrusion of migrated incisors with infrabony defects in
adult periodontal patients. Am J Orthod Dentofacial Orthop 2001;120:671–675.
Have a question you would like to see featured in this column?
Send it to: T. M. Graber, Editor-in-Chief
or E-mail to: [email protected]
University of Illinois at Chicago,
College of Dentistry
801 South Paulina, M/C 842
Chicago, Illinois 60612, USA
77
COPYRIGHT © 2002 BY QUINTESSENCE PUBLISHING CO, INC.
PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY.
NO PART OF THIS ARTICLE MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM
WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.