Tooth survival following various methods of sub-apical osteotomy

hit. J. oral Sttrg. 1972: 1:81-86 (Key words: ial~'~, o.~teotomy; tooth, vitality)

Tooth survival following various methods of sub-apical osteotomy D. H U T C H I N S O N A N D A. J. M A C G R E G O R

Dental School and Hospital, Leeds, England

ABSTRACT Color, firmness, radiographic change and thermal and electrical tests were employed to judge the quality of tooth survival following sub-apical osteotomy. Twenty-eight procedures were carried out on 24 patients putting 237 teeth at risk. Ten of these procedures were carried out in the incisor-canine region of the mandible by labial flap reflection. In the maxilla 3 Wassmund procedures were carried out, as well as a further 6 Wassmund procedures with the addition of a mid-line sagittal spilt and 9 Wunderer procedures. T h e period of follow-up varied from 6 months to 3 years. A total of 53 teeth which were adjacent to the site of section and undamaged at operation, survived unchanged. At first the 181 transposed teeth did not respond to stimulation, but 177 of these later returned to normal functional and esthetic value. No significant difference could be detected in the quality of survival of the teeth in the different procedures used. it is concluded that unpredictable tooth loss is unlikely as a result of any of the sub-apical osteotomy procedures used here. -

-

(Received for publieatiol~ 9 May, accepted 3 June 1972)

Sub-apical osteotomy is a t e r m used for the p r o c e d u r e in which teeth are transposed together with their supporting bone on a pedicle. W h e n the segment is mobilized the n e r v e and blood supply to these teeth is disrupted. In these circumstances it becomes interesting to k n o w if tooth loss is a result of these procedures and also to evaluate the functional and esthetic value of surviving teeth. Pulpal sensitivity and vascutarity m a y be affected as m a y be the periodontal tissues and root integrity.

To s o m e extent the first p r o b l e m has been answered in that the operations h a v e been carried out since 1928 and h a v e become widespread since K o l e ' s article in English (Kole 1959). It is unlikely t h a t the techniques would continue to be u s e d if there had been u n d u e loss of teeth. D e tailed studies of w h a t p u r p o r t s to be t o o t h vitality h a v e been carried o u t (Johnson & Hinds 1969, Leibold, Tilson & Rask 1971, J o h n E w i n g & D u e l 1970). J o h n s o n & Hinds (1969) claim that ahnost all t e e t h re-

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gain their blood supply and that 132/169 regain a nerve supply after six raonths. Leibold et al. (1971) found that 27 % of 60 teeth w e r e non-responsive to electrical stimulation aft er 12 months. As the pre-operatire state o f the teeth is not reported, it m a y well be that the surgical method is better than it appears, for many of the patients m a y h a v e had unsuccessful orthodontic treatment which itself m a y have resulted in pulpal changes. T h e second problem was whether different procedures gave different results. H e r e detailed evidence has been obtained by experimental work on monkeys (Bell 1969). Th e conclusion was that the segments could survive w h e n the entire labial mucosa was detached, if the nasal and palatal mucosa were kept relatively intact. The loss of a segment has been reported following a onestage procedure with very extensive flap reflection (Parries & Becket 1972). Some operators carry out two-stage procedures in order to preserve blood supply (Henry & Wreakes 1968). One-stage operations have been r e c o m m e n d e d for anterior maxillary osteotomy by Wassmund (1936) who preserves the palatal blood supply, and Wunderer (1962) who relies on the nasal and Iabial pedicles only. This present paper gives the results of sub-apical osteotomies in 24 patients and shows the quality of survival judged by various criteria in four different procedures.

CLINICAL MATERIAL The distribution of the operations performed is shown in Table 1. The 10 osteotomies in the anterior region of the mandible were carried out by an extensive labial flap. The 18 maxillary osteotomies were carried out by different techniques. In the 3 Wassmund procedures the nasal and Iabial pedicles were augmented by a palatal bIood supply preserved by tunneling under the palatal mucoperiosteum. Six patients required an increase in the intercanine width, and to do this the palatal flap was bi-

sected by a midline sagittal incision. In a further nine patients treated by the Wunderer procedure, the palatal flap was transected by excising a strip of mucoperiosteum coronally. Twelve procedures were carried out on males and 12 on females. The age range was 11-28 years. All operations were carried out under endotracheal anesthesia. Hypotensive techniques were not applied. Immobilization was by means of adjustable metal cap splints for 3-5 weeks without intermaxillary fixation (MacGregor 1972). The criteria used to judge the quality of tooth survival were color, mobility, reaction to heat, cold and electrical tests, and radiographic appearance. Heat was applied using guttapercha sticks of approximately 3.5 mm diameter with the terminal 5 mm held in a flame for 2 s, then applied to the middle of the labial surface of the tooth to be tested for 10 s or less if pain was caused (Mumford 1964). Cold stimulation was from a 6-mm diameter pledger of cotton wool held in tweezers and soaked in ethyl chloride until saturated. This was applied to the middle of the labial surface for 10 s or less if pain was caused (Mumford 1964). Electrical testing was carried out with the Scoones' type of pulp tester producing a square wave pulse of approximately 500 #s duration at a rate of 100 pulses per s, variable from 0-500 V peak output. This variation is produced by a pointer moving across a scale calibrated from 0-I00. Repeatability of recordings on different occasions by the same operator testing the same teeth on the same patient gave a variation of up to + 15 divisions so that it was necessary to consider ali teeth as having regained sensitivity if they responded at a stimuIus within 15 divisions of the pre-operative level. These special tests of stimulation by thermal and electrical means were carried out by the same operator in an attempt to reduce the number of variables. The teeth were tested pre-operatively and immediately after the splints were removed. Since the subsequent attendance of patients varied according to their particular needs, it was not possible to repeat tests on all teeth at similar intervals. In general, testing was carried out monthly, then every three months, six months and at present (April 1972) the longest follow-up reported is 3 years. Teeth tested were those on the mobilized segments and those teeth on fixed segments immediately abutting a line of section.

TOOTH SURVIVAL AFTER SUB-APICAL OSTEOTOMY

83

Table 1. Distribution of patients within procedures No. 10

Male 5

Female 5

Age range 14 -23

Maxilla (Wassmund)

3

3

0

12~-I6

21

6

Maxilla (Wassmund with midline split)

6

1

5

15 -23

47

12

Maxilla (Wunderer)

9

3

6

11 -28

56

18

Mandible

No. of teeth Pedicle Fixed 57 20

4 patients had both jaws treated at the same time

RESULTS FIXED TEETH ADJACENTTO A SITE OF SECTION

(a) Pre-operative There were 56 fixed teeth adjacent to a site of section all of normal color and mobility and without radiographic abnormality. One tooth was unresponsive to testing with electrical and thermal stimulation, while a further 4 teeth failed to respond to cold and heat only. F o u r other teeth were unresponsive only to heat. (b) Post-operative 3-5 weeks The behavior of the fixed teeth adjacent to a site of section was generally unchanged except where direct trauma by cutting instruments had occurred. One such tooth became loose and unresponsive, and a further two were removed at operation because the degree of trauma was considered to be excessive. Radiographic appearances showed clearly the lines of section, and root damage where it had occurred. (c) Post-operative follow-up period There were no late changes in the status of any of these teeth and the root damage previously shown radiographically h a d proved to be non-progressive. Bone formation had reestablished continuity between the fixed and mobilized teeth without depression of alveolar crest height or periodontal pocket-

ing as evidenced clinically and radiographieally.

PEDICLE-SUPPORTED TEETH (a) Pre-operative The 181 teeth which were to be transposed were tested. None was abnormally mobile but two were darker in color than their homologs. Five failed to respond to cold, 30 to heat, and two to electrical testing, these being the darkened teeth. Twelve had abnormal radiographic appearances of either root resorption or pulpal occlusion but none showed evidence of periapical pathology. There was virtually no correlation between these appearances and the results given by the tests used f o r pulpal response. See Table 2. (b) Post-operative 3-5 weeks Very few of these teeth responded to stimulation and two teeth adjacent to lines of section had darkened. Radiography showed three teeth to have been inadvertently apieeeted at operation, and a further four showed evidence of lateral root damage. All were symptom-free and of normal mobility. It was our impression that the teeth could be used normally as soon as the splints were removed, and few patients had difficulty with spatial localization of the segments. Surprisingly most patients ac-

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HUTCHINSON AND MACGREGOR

Table 2. The response of pedicle-supported teeth to testing Follow-up '. (months)

Number Number of paof tients teeth

Electrical stimulation

Ratio and % responding to: Cold Heat stimulation stimulation

Pre-operative

24

181

1 7 9 / 1 8 1 (99%)

176/181(96%)

1

12

84

33/ 84 (39%)

16/ 84 (19g)

2

11

73

39/ 73 (56%)

16/ 23 (23%)

13/ 23 (18%)

3

6

42

30/ 42 (71%)

21/ 42 (50%)

15/ 42 (35%)

6

12

83

80/ 83 (95g)

42/ 83 (51%)

38l 83 (43%)

I2

8

51

48/ 5i

(94g)

45/ 5I (88%)

35/ 51 (68%)

18

6

46

45[ 46 (98%)

37/ 46 (8O%)

37/ 46 (8O%)

30

2

12

12/ 12 (100%)

8/ 12 (67%)

8l 12 (67%)

eepted anesthesia of the teeth without complaint. Three patients who underwent maxillary push-back procedures and had anterior abnormal swallowing patterns experienced some difficulty in swallowing but only for the first 48 hours following operation. See Table 2. (c) Post-operative Jollow-up period None of the transposed teeth was lost as a result of surgery but one maxillary central incisor was lost in an accident 6 months post-operatively. Histologic examination of the pulp of this tooth showed vessels and nerves to be present. Three of the teeth of normal color at splint removal had darkened and had become unresponsive to testing, In the 7 teeth seen to have been damaged radiographically at operation, root destruction was not progressive and only one of these was unresponsive to all the tests. N o radiographic changes were seen in the Structures of the roots or supporting bone of the remaining teeth and mobility remained normal. A typical pattern of recovery could be discerned and was common to the teeth in

151/181 (84%) 7/ 84

(8%)

both jaws irrespective of the operative procedure used. Within 1 to 3 months of operation the first response to r e a p p e a r was that to electrical stimulation followed by response to cold, and later to heat. Over the year most teeth recovered to their pre-operative response level. As in the pre-operative testing, response to heat was the most commonly negative result. There was no general tendency towards regression in sensitivity over the period of the investigation, and the overall number of teeth recovering sensitivity, and the time in which they recovered, were comparable among the different procedures. See Table 3.

DISCUSSION The overwhelming result was that teeth survived the immediate period of operation and there were no changes detected to suggest that long-term survival was unlikely. Even teeth damaged at operation could be expected to survive unless the degree of trauma was excessive. This result is to be contrasted with the fate of autogenous tooth transplants (Natiella, A r m i t a g e &

TOOTH SURVIVAL AFTER SUB-APICAL OSTEOTOMY

85

Table 3. Results of testing 6 months after operation Procedure

Ration and % responding to: Cold Heat stimulation stimulation

No. of teeth

Electrical stimulation

20

20/20 (100%)

20/20 (100%)

18/20 (90%)

Maxilla Wassmund

7

7/ 7 (100%)

6/ 7 (85%)

51 7 (71%)

Maxilla Wassmund with midline split

33

30/33 (91%)

27]33 (82g)

26/33(79%)

MaxillaWunderer

18

16/18 (89%)

16/18 (89%)

15/18 (82%)

Mandible incisor/ canine surgery

Greene 1970) and autogenous transplants of osseous dental units (Luke & Boyne 1968). In both these procedures progressive root resorption is a common sequel and would seem to follow total disruption of the blood supply to the periodontal tissues. The absence of root resorption in sub-apical osteotomy procedures, therefore, suggests than an adequate blood supply has been maintained by the pedicles. These vascular pedieles may also transmit proprioceptive impulses along perivascular nerves and this mode of transmission may account for the virtual absence of proprioceptive problems. The clinical tests used to detect the presence of nervous elements in the pulp were electrical stimulation and exposure to heat and cold. However, these results cannot be used to determine accurately the histopathologic state of the pulp (Mumford 1967). A recent investigation has suggested that the electrical stimulator may be testing the periodontal membrane and not the pulp, since it was shown in the cat that there were receptors present in the periodontal membrane responding to a lower level of stimu. lation than those in the pulp (Mathews 1971). The periodontal membrane may also respond to transmitted pressure changes from a necrotic pulp chamber following

thermal change (Mumford 1964). Returning sensation may be interpreted, therefore, as a recovery of periodontal membrane sensitivity, as ingrowth of pulp nerves, or as the assumption of a sensory s by autonomic nerves accompanying in-growing blood vessels (Barton & Rayne 1969). Histologic evidence from autotransplants of human teeth has shown the presence of vascular pulps containing nerve fibers (Ohmann 1965, Thonner 1971). Histology of the pulps from sub-apical osteotomy procedures in human primates similarly shows blood vessels to be present (Bell :1.969, Poswillo 1972). Bell (1969) concludes that if surgical cuts do not encroach to within 5 mm of the apices of the teeth, the blood supply will be maintained; if the apex is involved directly, the pulp may be revascularized. Pulpal ischemia may result in the loss of the more specialized cells and their replacement by fibrous elements. The odontoblast layer seems to be particularly susceptible to ischemia and its disruption and partial loss is reported (Poswillo 1972). This may have the effect of retarding or preventing secondary dentin formation as a reaction to caries or attrition, and it m a y be that in the long term the teeth may have reduced chances of survival. A probable con-

86

HUTCHINSON AND MACGREGOR

clusion is that even the unresponsive teeth in this series have living pulps, and the absence of progressive radiographic or color change supports this view. REFERENCES BARTON, P. R. & RAYNE, J.: The role of alveolar surgery in the treatment of malocclusion. Brit. dent. J. 1969: 126: 11-27. BELL, W. H.: Revascularization and bone healing after anterior maxillary osteotomy', a study using adult rhesus monkeys. J. oral Surg. 1969:271 249-255. HENRY, T. C. & WREAKES, G.: The surgical repositioning of the labial segments in the treatment of malocclusion. Dent. Praetit. dent. Rec. 1968: 18: 329-341. Jorr~soN, J. V. & H~NDS, E. C.: Evaluation of teeth vitality after subapical osteotomy. J. oral Surg. 1969: 27: 256-257. IOnN, M. W., EWING, R. C. & DUELL, R. C.: Evaluation of teeth vitality following segmental alveolar osteotomy. ~Int. Ass. dent. Res. Meeting March 1970. Abstract No. 214, p. 102. KOLE, H.: Surgical operations o n the alveolar ridge to correct occlusal abnormalities. Oral Surg. 1959: 12: 277-288, 413-420, 515-529. LEIBOLD, D. O., TILSON, H. B. & RASK, K. R.: A subjective evaluation of the re-establishment of the revascular supply of teeth involved in anterior maxillary osteomy procedures. Oral Surg. 1971: 32: 531-534. LUKE, A. B. & BOYNE, P. J.: Histologic responses following autogenous osseous-dental

Address: D. Hutchlnsot, Dental School & Hospital Bhmdell Street Leeds LS1 3EU England

transplantation. Oral Surg. 1968: 26: 861870. MACGREOOR, A. J.: An adjustable locking plate for sectional metal cap splints. Brit. J. oral Sttrg. 1972: in press. GREENWOOD, F., HORCUCHI, H. & MATHEUS, B.: What do pulp testers test? d. dent. Res. 1971: 50: 1202. MUMFORD, J. M.: Evaluation of gutta-percha and ethyl chloride in pulp testing. Brit. dent. J'. 1964: 117: 338-342. MUMFORD, J. M.: Pain perception threshold on stimulating human teeth and the histolog{cal condition of the pulp. Brit. dent. J. 1967: 122: 427-433. NATIELLA, J'. R., ARMITAGE, J. E. & GREENE G. W.: Replantation and transplantation of teeth. Oral Surg. 1970: 2,9: 397-419. 0HMANN, A. O.: Healing and sensitivity to pain in young replanted human teeth. Odont. T. 1965: 73: 165-299. PARNES, E. I. & BECrmR, M. L.: Necrosis of the anterior maxilla following osteotomy. Oral Sure. 1972: 33: 326-330. POSWILLO, D.: Early pulp changes following reduction of open bite by segmental surgery. Int. I. oral Sure. 1972: 1: 87-97. THONr,mR, K. E.: Autogenous transplantation of unerupted maxillary canines: a clinical and histological investigation over 5 years. Dent. Pract. dent. Rec. 1971: 21'. 251-257. WASSMUND, M.: Lerbuch der praktischen Chlrargie des Mundes und der Kie/er. Meusser, Leipzig 1935: vol. I: p. 289-292. WONDERER, S.: Die Prognathie Operation mittets frontal gestieltern Maxillafragment. Ost. Z. Stomat. 1962: 59: 98-102.