Intrusion of incisors in adult patients with marginal bone loss

of incisors in adult patients with Birte Melsen, Nina Agerbaek,

and G&an Markenstam

Aarhus, Denmark Elongated and spaced incisors are common problems in patients suffering from severe per~od~~ta~ disease. Thirty patients characterized by marginal bone loss and deep overbite were treated by intrusion of incisors, Three different methods for intrusion were applied: (1) J hooks and extraoral high-pull headgear, (2) utility arches, (3) intrusion bent into a loop in a 0.17 x 0.25~inch wire, and (4) base arch as described by Burstone. The intrusion was evaluated from the displacement of the apex, incision, and the center of resistance of the most prominent or elongated central incisor. Change in the marginal bone level and the amount of root resorption were evaluated on standardized intraoral radiographs. The pockets were assessed by standardized probing and the clinical crown length was measured on study casts. The results showed that the true intrusion of the center of resistance varied from 0 to 3.5 mm and was most pronounced when intrusion was performed with a base arch. The clinical crown length was generally reduced by 0.5 to 1 .O mm. The marginal bone level approached the cementoenamel junction in all but six cases. All cases demonstrated root resorption varying from 1 to 3 mm. The total amount of alveolar support-that is, the calculated area of the alveolar wall-was unaltered or increased in 19 of the 30 cases. The dependency of the results on the oral hygiene, the force distribution, and the perioral function was evaluated in relation to the individual cases. It was obvious that intrusion was best performed when (1) forces were low (5 to 15 gm per tooth) with the line of action of the force passing through or close 1.0 the center of resistance, (2) the gingiva status was healthy, and (3) no interference with perioral function was present. (AM J ORTHOD DENTOFAC ORTHOP 1989;96:232-41.)

common problem in adult patients suffering from periodontal disease is the migration, elongation, and spacing of incisors.‘” Disjunction of the equilibrium between the available periodontal support and the forces acting on the teeth may result in positional changes. This frequently leads to trauma from occlusion, a situation that might enhance destruction of the periodontium if plaque-associated inflammatory lesions of the gingiva are present.4-7 Anterior teeth are specially prone to elongation since they are not protected by occlusal forces and have no anteroposterior contacts inhibiting migration.8 Masticatory forces are predominantly anterolaterally directed and little resistance exists, particularly if there is already an increased overjet. With progressive bone loss, the center of resistance moves apically’ and the forces acting on the crowns generate a larger moment, adding to the progressive displacement. Intrusion, retraction, and/or uprighting of incisors seem to be the liogical solution to the orthodontic problem of these patients when considered from causative,

8/l/11467

232

esthetic, and functional points of view. However, orthodontic correction of malaligned, tipped, or spaced teeth with horizontal and vertical bone losses may also be related to improvement of bone support. Geraci,” Brown,” and Sternlicht8 even suggest that orthodontic correction may contribute to regeneration of periodontal tissue. On the other hand, orthodontic treatment, especially that involving intrusive moverments, does include a risk of aggravation of the periodontal condition, 12-14 In support of this point of view, experiments carried out on dogs clearly demonstrate that ~~hodontic movement may shift supragingival plaque into a subgingival position and thereby result in formation of an infrabony pocket.” On the other hand, tipping of a tooth into an infrabony defect may result in a long epithelial attachment without further bony resorption, provided the oral hygiene is good.34 However, many authors have recommended forced eruption as the method of choice in the treatment of an osseous defect caused by periodontal disease. “J The advantage of this treatment is that a leveling of the marginal bone level takes place and diseased pockets can thereby be eliminated.lg However, a drawback is the occlusal reduction that is a necessary consequence

V&me 96 Number 3

Intrusion of incisors in adult patients with marginai bone loss

233

Fig. 1. Intraoral photographs of patients before (A and C) and after intrusion (B and D). A shortening of the clinical crown through treatment is obvious

Fig. 2. Appliances used for intrusion. A, J hooks for high-pull headgear. B, Utility-type arch used in combination with high-pull headgear to upper first molars. C, Intrusion bend into loops of full arch. D, Intrusion performed with base arch as described by Burstone. Point of force application is distal to the lateral incisors

of the lengthening of the crown and often leads to the need for prosthetic and endodontic treatment.2”,2’ If intrusion could be performed without any iatrogenie consequences, this would lead to reduced demands for reconstruction since the facial height would be unaltered and the clinical crowns would not be elongated. On the basis of pilot studies,‘2mU we decided to perform a series of orthodontic procedures on adult patients

in an attempt to intrude elongated teeth with varying degrees of periodontal damage for the purpose of studying the results clinically and radiographically and thus evaluating the influence of treatment on the periodontal status. Patients studied The subjects of this sample comprised 30 patients, five men and 25 women, aged 22 to 56 years. All

34

M&en, Agerback, and Markenstam

Fig. 4 . S c h e m a t i c d r a w i n g o f t h e i n d i v i d u a l f i l m h o l d e r u s e d f o r production of reproducible intraoral radiographs.

. 3. Rigid anchorage unit solders posterior teeth together, maximizing the anchorage.

patients had malocclusions in which intrusion of the upper incisors constituted a major part of the treatment. Xn 24 patients migration of incisors had been noted in relation to progressing periodontal disease. The remaining six patients observed spontaneous tooth displacement after the extraction of teeth in the posterior segment. The majority of the patients had increased length of the clinical crown, leaving a variable amount of cementum visible (Fig. 1). er~o~o~tal preparation

Before treatment all patients received adequate periodontal treatment involving instruction, cleansing, and curettage. In 15 patients a modified Widman flap operation was necessary to reduce to pocket depth to 3 mm or less. Apart from single localization with three wall pockets submitted to a thorough curettage during surgery this was obtained in all patients. Fixed appliances were inserted within 1 week after the surgical procedures. The gingival conditions were registered as sound, no bleeding was observed at probing, and the plaque index based on staining of the incisors was close to zero at the start of orthodontic treatment.

loop of a 0.017 x 0.025inch stainless steel wire (Fig. 2, C). All other patients (N = 22) were treated with a base arch intrusive mechanism, full or segmented, as described by Burstone (Fig. 2, 0). The point of force application was chosen after judging the position of the center of resistance (CR) for the incisor segment with regard to the desirable change in inclination (Fig. 4). The force used varied from 10 to 20 gm per tooth, depending on the amount of periodontal support. The anchorage consisted of a 0.036-inch transpalatal arch and two 0.021 X 0.026-inch stainless steel segments connecting all teeth within the posterior segment. In five cases in which single teeth had been lost or the periodontal support was seriously reduced, the bands on the teeth of the posterior segments were soldered together with a 1 .O mm stainless steel wire cross adapted to the palate and soldered to the side segments (Fig. 3). Periodontal cantrol

During treatment the patients were under continuous periodontal control and underwent subgingival curettage when considered necessary. Orthodontic ueatment time varied from 6 to 18 months. A number of patients (N = 5) needed further surgery following the orthodontic treatment since the retraction of an incisor often leads to an accumulation of gingival tissue and, as a consequence, pseudopockets lingual to the incisors. Analysis applied

Four different types of appliance were used for correction of the overbite by intrusion. One patient was treated by use of an edgewise appliance with a J hook for intrusion, adapted for 100 gm per side, as recommended by JanzenZ5 (Fig. 2, A). Four patients were treated by use of 0.016 x 0.016-inch edgewise utility arches with high-pull headgear as anchorage as described by RickettP as part of the Bioprogressive technique (Fig. 2, B). Three patients had t-be intrusion adjustments bent into a

Study casts, profile radiographs, and fuil intraoral clinical status assessment were made at the start of treatment and at the time of initiation of retention. In several cases reconstructions such as bridgework were performed. The alveolar bone level was measured on the intraoral radiographs taken with 70 kV tube voltage and a film focus distance of 20 cm, using a special film holder.28 In the first six cases, this film bolder was further developed with the purpose of increasing the reproducibility. A piece of 0.021 X 0.02%inch Hgiloy

Intrusion af incisors in adult patients with marginal bone loss

2

Fig. 5. Illustration of the film holder (Fig. 4) in use

wire was bent to fit the bracket of the individual incisor. The ends of the wire were heated and inserted into the plastic part of the film holder. The wire was adjusted so that the film was placed parallel to the long axis and perpendicular to the x-ray (Fig. 4, A and B). The individual film holder was kept for each incisor and used for exposures after treatment (Fig. 5). Since the benefit of this method was considered limited in relation to the resources used, the bone level was evaluated as described by Zachrisson and AIII~s~~-~” in the remaining 24 cases. The change in marginal bone level and root length caused by resorption was expressed by a percentage relative to the original root length. The intraoral radiographs, before and after intrusion, were magnified X 8. Drawings were made of external and internal structures of the tooth, the wire connected to the film holder, and the alveolar contour with special attention to the marginal bone level. Superimpositions were made with pulp structure and wire used as references (Figs. 6 and 7). The influence of the treatment OR root length and the marginal level of the bone supporting the incisor were evaluated through the estimation of the area of the root surrounded by the alveolus, the shape of which stimulated that of a cone. To obtain the best possible approximation, a differentiation in the apical region was fitted to a cone and the remaining root to a truncated cone. The calculations made to estimate the surface of the root surrounded by bone appear in Fig. 8. The amount of displacement of the most prominent control incisor was evaluated on the profile radiographs. A coordinate system was established, the X-axis being the palatal plane, the Y axis perpendicular through the reference point pterygomaxillare. To evaluate the validity of this method, four patients had tantalum implants’” inserted in the maxilla. To facilitate and im-

Fig. 6. Measurement made of the superimposed inrraoral radiographs. So/id line, Before treatment; dashed line, after intrusion.

prove the reproducibility, individual templates of the incisors from the first profile radiograph were produced for each individual patient. On these templates the center of resistance was marked according to the margmal bone level as described by Burstone and Pryputniewicz.g The orthodontic movement of the most prominent incisor was then expressed as the displacement of incision, apex, and the CR in relation to the previously mentioned coordinate system. The influence of the treatment on the gingival condition and esthetics was controlled in the following manner. On study casts at the start and at the end of treatment, the clinical crown height was measured from the incisal edge to the most apical margin of the gingiva labially, mesially, lingually, and distally. The same procedure was repeated on the study casts after treatment.

36

Melsen,

Agerbazk,

and Markenstam

Fig. 7. A, 6, and E, Radiographs of three incisors before intrusion. Note the marked marginal bone ioss. B , D, a n d F , s a m e t e e t h a f t e r i n t r u s i o n . N o t e t h e s l i g h t r o o t r e s o r p t i o n a n d t h e c o r o n a l d i s p l a c e m e n t of the marginal bone level.

Pockets were measured but since the only data available before treatment were statements from the periodontists that no pockets greater than 3 mm were available, the same check was performed after treatmentthat is, the localization and the depth of pockets greater than 3 mm were noted. Probing was performed labially, lingually, mesially, and distally on each of the four incisors.

At the start of treatment, the overjet of the patients varied from 3 to I7 mm. The overbite ranged from 3 to 14 mm with an average of 5.8 mm. The bone loss was likewise variable, the most dramatic found in patient no. 5 who had lost more than 60% of bone on two incisors. The least bone loss was close to zero found in three Glass II, Division 2 patients who had developed their deep bite in relation to ex-

traction of one or more premolars in the lower jaw. These extractions had been performed because of increasing crowding in both arches. The displacement of the most prominent incisor of the individual patients appears in Fig. 9. It is seen that the amount of intrusion varied greatly when judged by the displacement of the incision, apex, or the center of resistance. This variation was a result of the change in inclination and was related to the center of rotation of the total movement.32 The maximum intrusion observed at the apex was 5.0 mm. In relation to the type of appliance, it was obvious that the major intrusion: without corresponding apical root resorption, occurred as a result of the base arch. The horizontal movement of incision varied from a protrusion of 5.5 mm to a retraction of 10 mm. Treatment time varied from 6 to 18 months. The evaluation of the bony level as studied on the

Intrusion of incisors in adult patients with marginal bone loss

h

= height

s

= length of side

R

= radius of base

s1 = surface area

Truncated

cone

h

= height

S

= length of side

R1

= radius, upper

base

R2 = radius, lower base = surface area s2

s2

=Iji-'(R1

+ R2)s

s 3 - s 1 =x%ofS 1 +s 2 = gain/loss of attachment Fig. 8. Mathematic model of a cone and a truncated cone used for calculations of bony alveolus area. h, Height; s, length of side; r, radius; S, surface area.

enlarged intraoral exposures showed that the bony level had approximated the cementoenamel junction (Fig. 7). At the same time, apical root resorption also could be observed in all cases. The total influence of the orthodontic tooth displacement on the bony support was on average an increase of 6.8% with a minimum of minus 15% and a maximum of plus 22% (Table I). The measurement of the clinical crown length demonstrated a reduction of 1.08 mm, varying from an increase of 1.3 mm to a reduction of 3.8 mm. The reduction was the most pronounced lingually and least pronounced laterally. The periodontal assessment demonstrated that these patients had developed pockets of about 3 mm in all cases localized to the lingual surfaces. In four cases the pockets were pseudopockets, which could be ascribed to a dramatic lingual tipping of the incisors. In two cases the pockets were found in relation to a vertical

three-wall pocket. No teeth were beyond periodontal therapy. DISCIJSSION

The present article summarizes the effects of treatment carried out with the common purpose of intruding upper incisors. Apart from the need for intrusion, the patients varied considerably. Hence the individual tracings are presented. In some patients the intrusion was combined with proclination; in others, the majority, variable amounts of retraction and uprighting were needed. Also the level of the marginal bone varied greatly among the patients, some having experienced no bone loss, whereas others suffered from severe bone loss. However, the patients were accepted for treatment only when the periodontal condition was under control-that is, apart from single localization with vertical bone loss, no pockets of more than 3 mm could

Am J. Orthud. Deniofac. &hop. September 1989

Melsen, Agerhk, and Markenstarn

26

-

25

-

Fig. 9 (Cont’d). Fig. 9. lndividuai tracings of the 30 patients studied. Numbers correspond to those on Table I. Note the large individual variation related to variation in type of movement tipping-retraction. No root resorption can be noted since the tracings were performed with individually produced templates of the incisors.

be detected by the periodontist. This limitation was selected because Waerhaug34 had shown that deeper pockets are not easily subject to efficient curettage. It was considered crucial for treatment results that the gingival inflammation be kept at a minimum during treatment. Numerous studies have convincingly shown the detrimental effects of plaque, inflammation, and orthodontic tooth movement in combination,‘5J6.22 especially in relation to intrusion.35 Since the primary purpose of the study was to evaluate the result of the orthodontic treatment, we attempted to standardize the depth of the pocket, ensure good oral hygiene before treatment, and keep the periodontal condition under control throughout treatment.

The attachment level was not measured because it was anticipated that a long epithelial attachment as described following a successfully intrusion’4,36-38 might invalidate these measurements. Among the variables influencing the results, the following were studied: the variation in orthodontic appliances, individual responses to the orthodontic stimuli, and interaction of the responses with the forces acting on the teeth and the periodontium from occlusion and the tongue, lips, and cheeks at the start of treatment. In all four types of appliance used, an attempt was made to adjust the forces to the amount of existing periodontium. Thus the forces were generally lower than those recommended by the authors25,26,27 in describing the appliances. Only in the utility and base arches, however, was it possible to monitor the appliance to a low and constant force ranging from 10 to 25 gm per tooth. Since the number of patients with the four appli-

intrusion

of incisors in adult patients with

marginal bane loss

Tabie 1. Alteration occurring by intrusion in

crown length measured on study casts and in alveolar bone level measured on intraoral radiographs

Patient No.

Group 1 Patient 1 Group 2 Patient 2 Patient 3

Change in crown length

Change in bone in percent of calculated area of bony alveolus

(mm)

(%I

1.3

-A

20 0 - 10

- 1.5 0 10

Patient

4

Patient Group 3 Patient Patient Patient Group 4 Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient Patient

5

- 2.3 +0.2 - 1.2 -0.7

6 7 8

-1.0 -0.4 -1.2

9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

-0.7 1.3 - 1.3 -0.9 -0.8 -0.5 -2.6 -0.3 +2.1 -0.9 -0.1 - 1.2 -3.8 -2.1 -0.5 -1.1 -1.7 - 1.0 - 1.9 -3.0 -1.2 -2.4

x SD Minimum Maximum

1.08 1.14 -3.8 2.1

0 -5

- 15 0

10 1.5 2 12 0

15 20 15 0 10 8 9 10 18 22 6.76 9.03 - 15 22

antes varied greatly, no statistical comparison could be carried out. The utility arch and the base arch seemed to result in both the largest intrusion and the largest gain in bony support. The amount of intrusion carried out was related not only to the force system as shown by Dellingeti’ but also to the type of tooth movement produced-that is, the amount of sagittal movement and change in inclination. As anticipated, the largest vertical displacement was seen in cases with retroclination and the largest movement of CR was in cases of pure translatory intrusion. The maximum intrusion

-jp=-+ I

-rL /‘” ’ if-----

Fig. 9 (Cont’d).

of incision was seen in combination with pro&nation. Of all the patients treated, only two exhibited loss of periodontal tissue during treatment, a finding that confirmed the importance of the controlled periodontal status. Ericsson and associates3’ also found slight bone loss in some cases, but this could be ascribed to the fact that tooth movements were carried out by means of removable plates, which often are slightly extrusive due to tipping and rapidity of movement. A tooth can be extruded too fast for an adaptation of the periodontal ligament tissue, leading to a relative loss of attachment and supporting bone.” On the other hand, extrusion has been advocated as the method of choice in cases of vertical bone loss because apposition associated with extrusion can help to fill in vertical bone loss by apposition and result in a leveling of the alveolar bone.13,‘7 When relating the change in the distance between

a

M&en, Agerbczk, and Markenstam

the marginal gingiva and the cementoenamel junction to the amount of intrusion and the change in marginal bone level, it could be anticipated that major infrabony pockets had developed during treatment. The fact that pockets could not be measured clinically did not imply that new attachment had taken place, but could very well be a sign of resolution of the inflammatory process and an increase in resistance of the tissue to probing. In that case the patients had a long junctional epithelium extending below the level of the marginal bone. Histologic studies on monkeys of the effect of intrusion of previously extruded teethI did in fact show a coneshaped development around the teeth. This defect was filled in if inflammation of the overlying tissue could be controlled. The bone margin would in itself prevent the probe from reaching the epithelial junction. Similar findings have been described previously by Caton, Nyman and Zander,37 Moscow, Karsh, and Stein,36 and Melien and associates.38 Until recently the clinical observation of a new attachment would have been considered very doubtful. However, histologic studies of similar treatment of monkeys38 do support the possibility. Since a new attachment clearly has been shown to depend entirely on the possibility of repopulation of the cells migrating from the periodontal ligament,3g.40 it is hypothesized that the increased mitotic activity of the orthodontic stimu1us41’42 results in an improved prognosis for a new attachment. Regardless of the histologic reactions of the patients presented herein, it is fundamental to note that only rarely does orthodontic treatment have a detrimental effect. In most cases there is a defined beneficial effect on the periodontal condition of the patient when judged at the clinical and radiographic levels. Esthetically the patients in this study benefited from treatment. The orthodontic result was retained by a variety of retention appliances and/or prosthetic reconstruction. The periodontal status was maintained by regular control and by the meticulous hygiene expected of patients who are interested in orthodontic treatment, thus providing satisfactory results. Such patients generally are also highly motivated in the maintenance of teeth after treatment. Satisfaction is positively correlated with hygiene and maintenance .@ This is particularly true when there has been a dramatic improvement in alignment, tissue health, and overall esthetics. 1. Miller BH. Orthodontics for the adult patient. I. Introduction. Br Dent J 1980;148:97-100. 2. Miller BH. The orthodontic role in periodontal occlusal and restorative problems. Br Dent .I 1980;148:128-32. 3. Geiger AM. Orthodontic assistance in the restoration of adult dentitions-the deep overbite. NY J Dent 1985;55:89-98.

4. Ericsson I, Lindhe J. The effect of long-standing jigghng on experimental marginal periodontitis in the beagle dog. J Clin Periodontol 1982;9:497-503. 5. Lindhe J, Svanberg G. Influence of trauma from occlusion on progression of experimental periodontitis with beagle dogs. J Clin Periodontol 1974:1:3-14. 6 . Elichman I, Smulov JB. Effect of excessive occlusal forces upon the pathway of gingival inflammation in human. 3 Periodontol 1985;36:141-7. 7. Macapanpan IC, Weinberg JP. The influence of injury to the periodontal membrane on spread of gingival inflammation. J Dent Res 1954;33:263-72. 8. Stemlicht HC. Tooth movement in periodontal disease. Texas Dent J 1959;77:48-55. 9. Burstone CJ, Pryputniewicz RJ. Holographic determination of centers of rotation produced by orthodontic forces. AM J ORTHOD 1980;77:396-409. 10. Ceraci TF. Orthodontic movement of teeth into artificially produced infrabony defects in the rhesus monkey. A histological report. J Periodontol 1973;44:116. 11. Brown IS. The effect of orthodontic therapy on certain types of periodontal defects. Clinical findings. J Periodontol 1973;4:74254. 12. Thilander 8. Orthodontic tooth movement in periodontai therapy. In: Lindhe J, ed. Textbook of clinical periodontology. Copenhagen: Munksgaard, 1984. 13. Vanarsdall RL, Musich DR. Adult orthodontics: diagnosis and treatment. In: Graber TM, Swain BF, eds. Orthodontics: current principles and techniques. St. Louis: CV Mosby, 1985:791. 14. Me&en B. Tissue reaction following application of extrusive and intrusive forces to teeth in adult monkeys. AM J ORTHOD 1986;89:469-75. 15. Ericsson I, Thilander B, Lindhe J, Okamat H. The effect of orthodontic tilting movements on the periodontal tissues of infected and noninfected dentitions in dogs. J Clin Feriodontol 1977;4:278-93. 16. Polson A, Caton J, Polson AP, Nyman S, Novak J, Reed B. Periodontal response after tooth movement into infrabony defects. J Periodontol 1984;55:197-202. 17. Venrooy JR van, Yukna RA. Orthodontic extrusion of singlerooted teeth affected with advanced periodontal disease. AM J ORTHOD 1985;87:67-74.

18. Ingber JS. Forced eruption. Part 1. A method of treating isolated one and two wall infrabony defects: rationale and case report. J Periodontol 1974:45: 190-206. 19. Eliasson LA, Hugason A, Kurol J, Siwe H. The effect of orthodontic treatment on periodontal tissues in patients with reduced periodontal support. Eur J Orthod 1982;4:1-9. 20. Wagenberg BD, Eskow RN, Langer B. Orthodontic procedures that improve the periodontal prognosis. J Am Dent Assoc 1980;100:370-3. 21. Roberts WW, Chacker FM, Burstone CJ. A segmental approach to mandibular moiar uprighting. AM J ORTHOD 1982;81:177-84. 22. Melsen B. Treatment problems ir. adult patients. Studieweek 1980:219-36. 23. Melsen B. Die Bedeutung rationaler Biomechanik bei der orthodontischen Behandlung erwachsener Patienten. Prakt Kieferorthop 1986;1:5-14. 24. Melsen B. Stand der Erwachsenen -Kieferorthopadie-Wo liegen die Grenzen? Int Orthod Kieferorthop 1986: 12: 149-76. 25. Janzen EK. A balanced smile-a most important treatment objective. AM 5 ORTHOD 1977:72:359-72. 26. Ricketts RM, Bench RW, Gugino CF, Hilgers JJ, Schulhof RJ.

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Intrusion of incisors in adult patients with

Number 3

27. 28. 29.

30.

31.

32. 33.

34.

35.

36.

Biogressive therapy. Denver, Colorado: Rocky MountainiOrthodontics, 1979. Burstone CJ, Deep overbite correction by intrusion. AM J ORT H O D 1977;‘72:1-22. Eggen S. Beitrag zur Vereinfachung der Riintgentechnik. Quiniessenz 1972;23: il. Zachrisson BU, Alnaes L. Periodontal condition in orthodontically treated and untreated individuals. I. Loss of attachment, gingival pocket depth and clinical crown height. Angle Orthod 1973;43:402-I 1. Zachrisson BU, Ahues L. Periodontal condition in orthodontically treated and untreated individuals. Angle Orthod 1974; 44:4&-55. Bjiirk A. The use of metallic implants in the study of facial growth in children: method and application. Am J Phys Anthropal 1968;29:243-54. Smith RJ, Burstone CJ. Mechanics of tooth movement. AM J ORTHOD 1983;85:294-307. Dellinger EL. A histologic and cephalometric investigation of premolar intrusion in the Macaca speciosa monkey. AM J ORTHOD 1967;53:325-55. Waerhaug J. Healing of the dentogingival junction following subgingival plaque control. I. As observed on extracted teeth. J Periodontol 1978;49: 119-34. Ericsson I, Thilander B, Lindhe J, Okamoto H. The effect of orthodontic tilting movements on the periodontal tissues of infected and non-infected dentitions in dogs. J Clin Periodontol 1978;4:278-93. Moskow B, Karsh F, Stein S. Histological assessment of autogenous bone graft. J Periodontol 1979;50:291-300.

marginal bone loss

37. Caton J, Nyman S, Zander H. Histometric evaluation of periodontal surgery. II. Connective tissue attachment levels after four regenerative procedures. J Clin Periodontol 1980;7:224-31. 38. Melsen B, Agerbzk N, Eriksen J, Terp S. New attachment through periodontal treatment and orthodontic intrusion. AM J ORTHOD DENTOFAC~RTHOP 1988;94:104-16. 39. Nyman S, Karring T, Bergenholtz 6. Bone regeneration in alveolar bone dehiscences produced by jiggiing forces. J Periodont Res 1982;17:316-22. 40. Roberts WE, Jee WSS, Cell kinetics of orthodontically stimulated and non-stimulated periodontal ligament in the rat. Arch Oral Biol 1974;19:17-21. 41. Lindhe J, Nyman S, Karring T. Connective tissue reattachment as related to presence or absence of aiveolar bone. J Clin Periodontol 1984;11:33-40. 42. Sodeck J. A comparison of the rates of synthesis and turnover of collagen and non-collagen proteins in aduit rat periodontal tissues and skin using a microassay. Arch Oral Biol 1974;22:65565. 43. Graber LW, Lucker GW. Dental esthetic self-evaluation and satisfaction. AM J ORTHOD 1980;77:163-73. Reprint requests m: Dr. Birte Melsen Department of Orthodontics Royal Dental College Vennelyst Blvd. DK-8000 Aarhus C Denmark

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