Mandibular atrophy and metabolic bone loss

Int. J. Oral Surg, 1985: 14: 16-21 (Key words: atrophy, mandibular; augmentation, ridge; osteotomy, sandwich; metabolismt

Mandibular atrophy and metabolic bone loss Mandibular ridge augmentation by combined sandwich-visor osteotomy and resorption related to metabolic bone state J. BRAS, C. P. VAN OOlJ AND H. P. VAN DEN AKKER Departments of Pathology, Dental Radiology and Oral Surgery, Academic Medical Centre and Dental Institute of the University of Amsterdam, The Netherlands ABSTRACT - 22 edentulous women, 11 with and 11 without signs of metabolic bone loss were treated by a combined sandwich-visor osteotomy. Longitudinal studies showed a higher rate of resorption in women with radiographic signs of metabolic bone loss. The analysis was based upon lateral cephalometry.

(Receiued for publication 6 June 1983, accepted 19 March 1984)

A relation between mandibular atrophy and metabolic bone loss has recently been suggested by ROSENQUIST et al.", BAYS & WBINSTElN 1 and BRAS et a1. 4 ROSENQUIST et al:? found in all patients of a series of 12 patients with a severe mandibular atrophy and referred for vestibuloplasty of the mandible a significant reduction of bone calcium mass in the radius, when compared with an age-matched control group of normal, dentate persons", BAYS & WEINSTEIN 1 found in 4 patients of a group of 10 patients with a severe mandibular atrophy and referred for osseous mandibular augmentation both radiological and histomorphometrical evidence for metabolic bone loss. This ratio corresponds with the findings of BRAS et al.4, who found in 29 patients (42%) of a series of 69 patients with a severe atrophy of the mandible and referred for osseous man-

dibular augmentation indications for metabolic bone loss, by measuring the cortical thickness at gonion. If systemic bone loss is found to be a causative factor, as the aforesaid findings suggest, in about half of the patients with a severe mandibular atrophy, and if these patients are treated by osseous ridge augmentation, then it is reasonable to assume that loss of the newly acquired ridge will be faster in patients with indications for metabolic bone loss than in patients without indications for metabolic bone loss. As suggested in our previous study", this paper reports on the relation between metabolic bone loss and loss of gained ridge in edentulous women with a severe mandibular atrophy who have been treated with a combined sandwich-visor osteotomy with interpositional and peripheral bone grafting.

17

ATROPHY, METABOLISME, AUGMENTATION

AgedistributiOAlt 1.1and folloii-ull a fter1.1oneall! ridge augmentation of 11 edentLllous women ....itha ce-treet thicknnsat ganiano'1mll1 Qrrnore

\2.

"

'0

'"

so

"

)'urs

Fig. 1. Assessment of ridge gain and subsequent loss on lateral cephalographs along fixed lines (LO, Ll, L2).

Fig. 2. Age distribution and follow-up in 11 edentulous women without indications of metabolic bone loss.

Material and methods

cephalometric radiographs, made at the following points of time: pre-operative, immediately postoperative (to), 3 (t3), 6 (t6), 12 (tl2) and 24months (t24) after ridge augmentation. The to, t3, t6, t12 and t24 tracings were superposed on the tracing of the preoperative radiograph. Measurements were made along three lines (LO, Ll, L2) (Fig. J). For this purpose, 3 auxilIary lineswere drawn: the tangent to the lower border of the mandible through menton (mandibular plane), the tangent to the posterior border of the ramus and the condyle (ramal) and the tangent to the most anterior point of the symphysis (pogonion), perpendicular to the mandibular plane. The length of the mandibular plane was limited by points of intersection with the anterior and posterior tangents. Line 0 was defined as the line through the middle point of the mandibular plane and perpendicular to this plane. Lines 1 and 2 were parallel to line 0 and situated 1 and 2 em ventrally to it, -respectively. Along these lines, the height of

During the period January 1979 to April 1982, 80 edentulous patients (17 men, 63 women) with a severe atrophy of the mandible were treated with a combined sandwich-visor osteotomy with interpositional and peripheral bone grafting". In only 31 of these 80 patients (9 men, 22 women) were adequate pre- and post-operative radiographs available. Based on the cortical thickness at gonion 2 • 3 , this group of 31 patients was divided into a subgroup of 15patients (4 men, 11 women) with radiographic indications of metabolic bone loss (cortical thickness at gonion less than 1 mm) and a subgroup of 16 patients (5 men, 11 women) without radiographic indications of metabolic bone loss (cortical thickness at gonion 1 mm or more)", Since the results of this study may be distorted by possible sex differences that cannot be detected because of the low number of male patients, for this study it was decided to use only the 22 female patients (11 with and 11 without radiographic indications of metabolic bone loss). Of these 22 female patients, the first one was operated on in February 1979, the last one in April 1982. The gain in ridge height and the subsequent loss of height were assessed on tracings of lateral A!ll!distrlbutfonat 1.1and follo.... -up afh:rl4l osseous rid!leaugml!ntalion of '1 edenllliolls ....omen witha cortical thickness a~ gonion of tess than!lIlrn

month

o

1"~

:'~ ~',,::::::.: ::: corlitilthicknel5itgonion

10

--1I11mormore ..... .. Ius than1mm

·--~-·--·-······~.linell •

lineD

24 months " Fig. 4. Loss of augmented ridge in edentulous

12

'0

40

Fig. 3. Age distribution and follow-up in 11 edentulous women with indications of metabolic bone loss.

women without indications of metabolic bone loss (uninterrupted line, Table 1)and with indications of metabolic bone loss (interrupted line, Table 2) along various measuring lines (Fig. 1) at various intervals.

BRAS, VAN 0011 AND VAN DEN AKKER

18

The results are summarized in Fig. 4 and the Tables 1-4. In these tables, the differences in the number of measurements after various

time intervals are the result of an incomplete follow-up, as shown in Figs. 2 and 3. The limited number of measurements at LO, when compared with Ll and L2 is due to the fact that in 4 of the 11 women without indications of metabolic bone loss (Tables 1 and 3) and in 3 of the 11 women with indications of metabolic bone loss (Tables 2 and 4), the distal limitation of the osseous ridge augmentation has been situated anteriorly to LO, but posteriorly to Ll. Between patients with and without indications for metabolic bone loss, no significant differences were found for the preoperative height at LO, L1 and L2, the initial ridge gain (RO) and L1 and L2 and the immediate postoperative (to) total mandibular height at LO, L1 and L2 (p>O.l). A slight, but not significant difference (O.05
Table 1. Ridge gain at various points of time, expressed as %s of initial ridge gain (Ht/HO %) in women without indications of metabolic bone loss (cortical thickness at gonion 1 mm or more)

Table 2. Ridge gain at various points of time, expressed as %s of initial ridge gain (Ht/HO %) in women with indications of metabolic bone loss (cortical thickness at gonion less than 1 mm)

the augmented ridge (total height minus preoperative height) was established by measuring the distance between the uppermost contour of the pre- and post-operative alveolar ridge at various points of time (Ht, HD, H3, H6, Hl2 and H24). Ridge gain at various points of time was expressed as %s of initial ridge gain (Ht/HD %). The preoperative mandibular height was also established along LO, L I and L2, by measuring the distance between the inferior border and the uppermost contour of the alveolar ridge. When both inferior borders were not at the same level, the distances between the uppermost contours of the alveolar ridge and the lower border were used. The statistical analysis comprised Wilcoxon's test for differences between the two groups of patients for preoperative mandibular height, initial ridge gain (HO), immediate postoperative (to) total mandibular height (preoperative height plus HO), HtjHO % and differences between LO, L1 and L2 for HtjHO % in both groups. Spearman's correlation test was used for the relation between Hl2/HO % and initial ridge gain (HO) , and between H12jHO % and immediate postoperative (to) total mandibular height. As the level of significance, p < 0.05 was chosen. Of the 11 edentulous women without radiographic indications of metabolic bone loss and the 11 edentulous women with radiographic indications of metabolic bone loss, the age-distribution at time of operation (to) and follow-up are shown in Figs. 2 and 3, respectively.

Results

Line 0

Line 1

HtjHO %

N

X

N

X

H3jHO % H6/HO % H12jHO % H24/HO %

6

71.3 58.7 33.8 14.0

10 8 11 10

85.1 80.5 67.5 53.0

6

7 6

Line 2 N

X

10 90.0 8 11 10

83.5 73.5 58.2

Line 0 Ht/HO %

N

H3jHO % H6jHO % Hl2/HO % H24/HO %

7 8 6 3

X

Line 1 N

75.7 8 59.1 11 27.7 9 19.0 6

Line 2

X

N

X

83.7 71.9 59.6 28.7

8 11 9 6

89.2 78 60.7 47.2

19

ATROPHY, METABOLISME, AUGMENTATION

Table 3. Preoperative mandibular height, initial ridge gain eHO) and relative ridge gain after 12 months (H12/H0 %), measured along fixed lines (Fig. 1) in women without indications of metabolic bone loss Preoperative mandibular height (mm) Patient 1

2 3 4 5 6 7 8 9 10 11

X

LO

Ll

L2

12.5 10.5 12 12 9.5 10 15

14 10.5 13 18.5 14 12 20 14

9 13.5 12.5

13.5 8.5 11 13.5 8.5 9 14.5 11 11 14.5 11.5

11.6

11.5

14.5

11

13 16 14.5

Resorption of the augmented ridge was found to be non-uniform. In both groups of women, the resorption was more pronounced in the posterior regions. In the group of women with indications of metabolic bone loss, statistically significant differences were

Initial ridge gain HO (mm) LO 4.5

4 10 4

L1

L2

6.5 11 9 9

12

9

3

6 9 4.5 7 10 10

5

8.3

3 6.5

11

9 7 10 11

13 13 8.5

HI2/HO % LO

44 27.5 40 25

L1

L2

46 86 50 61

63 68 78 79 100 73 77 85 71 41 73

89 83 78

44

11

17 23 50

86 50 70

10.6

33.8

67.5

11

73.5

noted between LO and L1 after 12 months (p
Table 4. Preoperative mandibular height, initial ridge gain (HO) and relative ridge gain after 12 months (HI2/HO %), measured along fixed lines (Fig. 1) in women with indications of metabolic bone loss Preoperative mandibular height (mm) LO

L1

L2

7 8 9 10 11

11 10 12 13 13.5 7 13.5 15 14 9 7

9.5 9 11.5 11.5 11 7 10.5 12 14 9 7

10.5 12 13.5 14.5 10 10 10 14 16.5 14 9.5

X

11.4

10.2

12.2

Patient 1 2 3 4 5

6

Initial ridge gain HO (mm) LO

9 10

7 2.5 4 11.5 8.5 14.5 8.4

L1

L2

5 14.5 13 8 7.5 10 4.5 10 13 11 16

7.5 17 10.5 8 7.5 12.5 6.5 8 12 10 15

10

10.4

HI2/HO % LO 55 20

43

Ll

L2

60 79 54 31 67 55

67 59 67 63 53

67

60

0 13 35

65 58

54 69 54

27.7

59.6

60.7

20

BRAS, VAN OOIJ AND VAN DEN AKKER

11 after 6 months (p<0.05), 12 months (pO.l).

Discussion In this study, loss of osseous ridge augmentation was established by measuring on tracings of lateral cephalographs with the help of fixed lines, at various time intervals. In this way, the osseous ridge augmentation has been evaluated from anteriorly to posteriorly in edentulous women without and with indications of metabolic bone loss. The osseous ridge augmentation was performed by a combined sandwich-visor osteotomy with interpositional and peripheral bone grafting, as described by DE KOOMEN et al. 7. Lateral cephalographs, when made in the same cephalostat with a fixed focus-film distance, as has been done in this study, are standardized radiographs, preeminently suited for evaluating long-term changes in longitudinal studies. On these lateral cephalographs, it is impossible to distinguish between left and right. However, when superposing tracings of pre- and the postoperative radiographs and when using the uppermost border of the alveolar ridge of both superposed tracings and when measuring along fixed lines, loss of ridge augmentation can be evaluated. While preparing this paper, a study of MERCIER et al. s appeared, in which the results of various mandibular ridge augmentation procedures were evaluated by the use of cephalographs with

the help of fixed lines comparable to the lines used in this study, and also using the limitation of the uppermost alveolar border. In their discussion on methods used to asses ridge gain and ridge loss, they concluded that lateral cephalometry remains the best method of assesment presently available. The results of this study have shown a significant relation between resorption rate and metabolic bone state and between resorption rate and location. These differences have not been influenced by preoperative mandibular height, the amount of initial ridge gain (HO) or immediate postoperative total mandibular height, since, with respect to these values, no significant differences were found between women with and without indications of bone loss, and no correlation was found between the amount of initial ridge gain and the relative ridge loss (Ht/HO %). In the group of women without indications of metabolic bone loss, in the anterior part of the mandible (L2), the resorption rate was found to be significantly lower than in the group of women with indications of metabolic bone loss. In the posterior direction, this significance was lost. This might be due to an increasing resorption of the osseous augmentation in a posterior direction in both groups, which was significant for LO and Ll and for LO and L2. The increase in resorption in a posterior direction and especially the marked resorption in the most posterior part (LO), can be explained by the ridge augmentation procedure followed. In the anterior part (L2), the iliac bone graft is placed interpositionally and is covered cranially by a broad segment of soft tissue pedicled mandibular bone. In this region, in the patients with and without indications of metabolic bone loss, after 24 months, ridge gain was found to be 47.2% and 58.2%, respectively, of the initial ridge gain (Tables 1 and 2) and averaged 54.1%.

ATROPHY, METABOLISME, AUGMENTATION

21

This is in accordance with the findings of ns References KOOMEN 6 • In his series of 50 patients treated 1. BAYS, R. A. & WEINSTEIN, R. S.: Systemic bone with a combined sandwich-visor osteotomy disease in patients with mandibular atrophy. J. OraIAfaxillojac.Surg. 1982: 40: 270-272. with interpositiona1 bone grafting, after 24 months, ridge gain was 52.7% of the initial 2. BRAS, J., OOIJ, C. P. VAN, ABRAHAM-INPIJN, L., KUSEN, G. J. & WILMINK, J. M.: Radiographic ridge gain. interpretation of the mandibular angular corIn the posterior direction, in our patients, tex. A diagnostic tool in metabolic bone loss. Part 1. Normal state. Oral Surg. 1982: 53: 541the bone grafts are placed peripherally to a 545. raised lingual segment of the mandible. At 3. BRAS, r., OOIJ, C. P. VAN, ABRAHAM-INPIJN, L., this region (11), in patients with and withWILMINK, J. M. & KUSEN, G. J.: Radiographic out indications of metabolic bone loss, after interpretation of the mandibular angular cor24 months, ridge gain was 28.7% and tex. A diagnostic tool in metabolic bone loss. Part II. Renal osteodystrophy. Oral Surg. 53.0%, respectively, of the initial ridge gain 1982: 53: 647-650. and averaged 43.8%. These findings are 4. BRAS, J., OOIJ, C. P. VAN, DUNS, J. Y., WAN8 comparable to those of MERCIER et at. who SINK, H. M., DRIESEN, R. M. & AKKER, H. P. found a mean gain in ridge height of 46% of VAN DEN: Mandibular atrophy and metabolic bone loss. A radiologic analysis of 126 edentuthe original ridge gain, in patients treated lous patients. Int. J. Oral Surg, 1983: 12: 309with a visor-osteotomy and peripheral bone 313. grafting after 18 months, in the same region. 5. FAZILI, M., OVERVEST-EERDMANS, G. R. VAN, In the most posterior part of the ridge VERNOOY, A. M., VISSER, W. J. & WAAS, M. A. augmentation (LO), in our patients the J. VAN: Follow-up investigation of reconstruction of the alveolar process of the atrophic raised lingual segment was minimal and the mandible. Int. J. Oral Surg. 1978: 7: 400-404. peripherally placed bone graft acted more as 6. KOOMEN, H. A. DE: De verhoging van de geresan on1ay graft, than as a true peripheral orbeerde mandibula. Thesis, Katholieke Unigraft. At this region, in patients with and versiteit van Nijmegen 1982. without indications of metabolic bone loss, 7. KOOMEN, H. A. DE, STOELINGA, P. J. W., TIDEMAN, H. & HUYBERS, T. J. M.: Interposed after 24 months, the gain in ridge height was bone-graft augmentation of the atrophic ma19.0% and 14.0% of the initial ridge gain, ndible. A progress report. J. Maxillofac. Surg, respectively, and averaged 15.7%. These 1979: 7: 129-135. findings are comparable to those of F AZILI 8. MERCIER, P., CHOLEWA, 1., DJOKovIc, S., MASELLA, R. & VINET, A.: Mandibular ridge auget at. 5, who found 24 months after on1aymentation and resorption with various visor grafting, a ridge gain of 11 % of the initial procedures. J. Oral Maxillofac. Surg. 1982: 40: ridge gain. 709-713. In our patients with and without indica- 9. ROSENQUIST, J. B., BAYLINK, D. J. & BERGER, J. S.: Alveolar atrophy and decreased skeletal tions of metabolic bone loss, the method of mass of the radius. Int. J. Oral Surg. 1978: 7: augmentation used in the posterior parts 479-481. has resulted in an accelerated resorption; which apparently overrules differences in resorption between the 2 groups studied. Address: However, our findings in the more anterior J. Bras parts once again suggest a roll of metabolic Academic Medical Centre University of Amsterdam bone loss in the pathogenesis of mandibular Department of Pathology atrophy. Meibergdreef 9 Acknowledgements - We wish to thank Mr. A. J. Dons and Mr. B. Kruys for their photographic help and Mrs. Y. O. Emmer-van den Hurk for her help in preparing the manuscript.

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