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Although the management of the alveolar cleft remains controversial secondary alveolar bone grafting is the most widely accepted approach. The results of a series of 71 secondary alveolar bone grafts performed between 1990 and 2001 on 58 patients with complete cleft lip and palate 13 of which were bilateral are presented. Bone grafts were assessed when the canine tooth had fully erupted using periapical dental radiographs.
The occlusal level of the newly obtained interdental bone of each grafted cleft was recorded and categorised in accordance with the Oslo grading system as described by Bergland. In addition the basal level of each bone graft was recorded. In this way total bone graft height was measured and each graft was categorised with respect to the desired normal height of noncleft interdental alveolar bone. This modified analysis grades more precisely the efficacy of secondary alveolar bone grafting and helps to identify and categorise those patients with insufficient bone for dental, orthodontic and orthognathic rehabilitation and those who may require further investigation and regrafting.
A number of different modalities of treatment have been advocated for the management of the alveolar cleft. Before the 1970s primary alveolar bone grafting (before palatal closure) was commonly performed until its adverse developmental effects on maxillary growth were highlighted by Koberg
long-term follow-up results are awaited. With the advent of modern presurgical orthopaedics gingivoperiosteoplasty has been proposed as an alternative to primary alveolar grafting.
The primary objectives of secondary bone grafting are the formation of a continuous and stable dental arch and the provision of an osseous environment which encourages canine eruption, is responsive to the orthodontic movement of teeth and facilitates complete dental rehabilitation or prosthodontic reconstruction. Other objectives include the elimination of oronasal fistulae, the provision of greater periodontal support for teeth adjacent to the cleft and the augmentation of bony support for the lip and alar base.
These methods attempt to map segmentally the height, thickness and position of bone adjacent to the roots of the cleft teeth. However, such bone and particularly that of the central incisor is predominantly native alveolar bone and is not indicative of bone graft success (Fig. 1(A)) . Moreover, these methods of analysis are subject to inter and intra-observer variability and are less useful in clinical management, audit and comparative study. The Bergland
With this system the occlusal level (Fig. 1(A)) of the interdental bone graft is compared with that of the normal side and a four-point scale is used to categorise each graft (Table 1) . In our study, the Bergland scale
is used not only to evaluate the occlusal levels of bone grafts but their basal levels also. By recording both levels total bone graft height is measured. The Bergland scale is extended further to categorise such heights by comparing them with the normal height of noncleft interdental alveolar bone (Fig. 1). In this way bone graft success can be more precisely measured and patient categories become more clinically significant.
Fig. 1(A) The Bergland grading system records only the occlusal level of the bone graft. Its four-point scale compares this level to that of normal interdental bone. This corresponds to the level of the amelocemental junctions of the cleft teeth. Native alveolar bone surrounds the root of the cleft central incisor and much of that of the cleft canine. (B) In this study the basal level of the graft is also recorded and compared with that of normal interdental bone. The latter corresponds to the level of the root apices and anterior nasal spine. (C) Once the occlusal and basal levels of the graft are evaluated total bone graft height at the mid-region of the cleft is measured.
A series of 71 secondary alveolar bone grafts performed between 1990 and 2001 on 58 patients with complete cleft lip and palate, 13 of which were bilateral, were reviewed. This series includes only those whose cleft canine or lateral incisor was in its fully erupted position at follow-up. The mean age at the time of bone grafting was 10.5 years, with a range of 9–13 years. When required, orthodontic treatment was performed prior to grafting to correct major irregularities in the position of the central incisors, to reposition and stabilise dislocated segments and to provide the surgeon with better access for graft placement and soft tissue closure. In accordance with most centres bone grafting was performed when development of the adjacent canine root was 50% complete.
with autogenous cancellous iliac bone were used throughout in this series. Orthodontic treatment was resumed 3 months after the bone grafting.
The mean follow-up time between grafting and the current radiographic assessment was 4.5 years, with a range of 6 months to 10 years. A 3×4 cm periapical dental radiograph was taken of each grafted alveolar cleft. The small size of the dental X-ray film facilitates its placement by the patient's index finger palatally and parallel to the alveolar ridge. The standard X-ray tube with its shutter almost closed is orientated so that only an appropriately sized X-ray beam passes perpendicularly through the alveolar ridge to the dental film. The occlusal level of the newly obtained interdental bone in the alveolar cleft was recorded and categorised according to the Bergland scale
(Fig. 1(A)). Principally, this compares this level of the bone graft with that of normal interdental bone, which approximates the amelocemental (crown-root) junction of the adjacent teeth in the corresponding radiograph. Using this method of assessment the alveolar bone grafts and patients were categorised into one of four types (Table 1).
Bone grafts were analysed further by recording their basal levels also (Fig. 1(B)). By comparing these basal levels with that expected of normal interdental bone in corresponding radiographs (Fig. 1(B)) they were categorised using the Bergland scale. Once the occlusal and basal level of each graft was established its total height at the mid-region of the cleft was measured (Fig. 1(C)). These actual bone graft heights were compared with the expected height of normal interdental alveolar bone in corresponding radiographs. The latter extends from the amelocemental junction (ACJ) occlusally to the root apices of the incisors and canine basally at the level of the pyriform aperture and the anterior nasal spine (ANS). By such comparison total bone graft heights were also categorised into to one of four types using the Bergland scale.
the distribution of alveolar bone graft levels within its four categories is shown in Fig. 2(A). Of the 71 grafts, 43 (60.5%) and 23 (32%) were recorded in category I (Fig. 3, Fig. 4, Fig. 5) and II (Fig. 6) , respectively. Thus, occlusal levels at normal or at more than three quarters normal heights were achieved in over 90% of bone grafts. Four grafts (6%) had occlusal levels at less than three quarters normal heights (type III) and one patient had complete graft failure (type IV) (Fig. 7) .
Fig. 2(A) The distribution of the various types of bone grafts using the Bergland grading system in which occlusal levels alone are recorded (N=71). (B) The distribution of bone graft types when their basal levels alone are evaluated. (C) The distribution of total bone graft heights measured after both the basal and occlusal levels have been recorded. Both bone graft basal levels (B) and heights (C) are categorised with respect to their expected normal values using the same scale described in the Bergland grading system (Table 1).
Fig. 3The occlusal level of the alveolar bone graft reaches the level of the amelocemental junction (ACJ) and hence it is categorised as a Bergland type I bone graft. Since its basal level extends to the desired normal level it is considered a type I graft using the Bergland scale. Its total height is that of normal interdental bone and it is therefore also considered a type I bone graft. (1) Central incisor; (2) lateral incisor when present; (3) canine; (4) first premolar. An asterisk marks the ACJ of the adjacent cleft teeth and therefore one lies on either side of the grafted cleft. The broken line represents the desired basal level of bone grafts and therefore passes from the apex of the canine root to that of the central incisor. This approximates the expected level of the pyriform margin laterally and the ANS medially.
Fig. 4The occlusal level of the bone graft extends to the level of the ACJ (Bergland type I) but its basal level does not quite reach the desired normal level and is therefore categorised as a type II graft. Its total height is at least three quarters of normal and therefore by height analysis it is also considered a type II graft. Some slight absence of bone graft around the apex of the canine root (type II) is unlikely to influence the final position of its crown. (1) Central incisor; (2) lateral incisor when present; (3) canine; (4) first premolar. An asterisk marks the ACJ of the adjacent cleft teeth and therefore one lies on either side of the grafted cleft. The broken line represents the desired basal level of bone grafts and therefore passes from the apex of the canine root to that of the central incisor. This approximates the expected level of the pyriform margin laterally and the ANS medially.
Fig. 5The occlusal level of the bone graft extends to the level of the ACJ (Bergland type I) but less than three quarters of normal inter-dental alveolar bone height has been achieved. By both basal and height analysis it is categorised as a type III graft. Significant absence of bone graft around the root apex of the mesially tilted canine prevents its bodily movement to a desired upright and a more functional position. (1) Central incisor; (2) lateral incisor when present; (3) canine; (4) first premolar. An asterisk marks the ACJ of the adjacent cleft teeth and therefore one lies on either side of the grafted cleft. The broken line represents the desired basal level of bone grafts and therefore passes from the apex of the canine root to that of the central incisor. This approximates the expected level of the pyriform margin laterally and the ANS medially.
Fig. 6The occlusal level of the bone graft just fails to reach the level of the ACJ (Bergland type II). Its base fails noticeably to extend to the desired level. Less than three quarters of normal height has been achieved. By both basal and height analysis it is categorised as a type III graft. When apical root resorption affects a cleft incisor the contralateral central incisor or ANS is used to indicate the desired basal level of the bone graft medially. (1) Central incisor; (2) lateral incisor when present; (3) canine; (4) first premolar. An asterisk marks the ACJ of the adjacent cleft teeth and therefore one lies on either side of the grafted cleft. The broken line represents the desired basal level of bone grafts and therefore passes from the apex of the canine root to that of the central incisor. This approximates the expected level of the pyriform margin laterally and the ANS medially.
Fig. 7Complete failure of bone graft. Thus by occlusal (Bergland), basal and height analysis it is considered a type IV graft. At regrafting the vestigial lateral incisor was extracted to remove a possible source of infection. (1) Central incisor; (2) lateral incisor when present; (3) canine; (4) first premolar. An asterisk marks the ACJ of the adjacent cleft teeth and therefore one lies on either side of the grafted cleft. The broken line represents the desired basal level of bone grafts and therefore passes from the apex of the canine root to that of the central incisor. This approximates the expected level of the pyriform margin laterally and the ANS medially.
The distribution of the various types of bone graft basal levels using the Bergland scale is shown in Fig. 2(B) and is similar to that of their occlusal levels. Of the 71 grafts 47 (66%) and 18 (25.5%) were recorded in category I (Fig. 3) and II (Fig. 4), respectively. Five grafts (7%) had basal levels at less than three quarters normal height (type III) (Fig. 5, Fig. 6).
This distribution of bone graft types is altered considerably when actual bone graft height (relative to the normal height of interdental bone) is assessed (Fig. 2(C)). Of the 71 grafts 27 were recorded in both type I (Fig. 3) and type II (Fig. 4) categories. Thus, normal heights and heights greater than three quarters of normal were achieved only in 76% of bone grafts. In this analysis 16 grafts (22.5%) were considered to have achieved heights less than three quarters normal height (type III) (Fig. 5, Fig. 6).
3. Discussion
Using the Oslo grading system as described by Bergland
90% of the bone grafts in this review achieved occlusal bone levels at or greater than three quarters normal height and were therefore categorised as type I or type II (Fig. 1, Fig. 2). With respect to the literature generally, this distribution of occlusal bone levels compares well with the highest reported rates of 80–90% by others
all of whom used the Bergland grading system. Types I and II Bergland levels are regarded as successes and lower heights may be sufficient for arch stabilisation and prosthodontic support.
The principle objectives of alveolar bone grafting are the formation of a stable dental arch and an osseous environment that facilitates canine eruption and orthodontic manipulation or prosthodontic reconstruction. Others include the provision of greater periodontal support for teeth adjacent to the cleft and the augmentation of bony support for the lip and alar base.
In order to meet these objectives a sufficient height and volume of bone must be provided. Any system of analysis must attempt to measure these parameters so that the true efficacy of bone grafts can be determined.
In this study the Bergland scale has also been used to grade both the basal levels (Fig. 1(B)) and total heights (Fig. 1(C)) of bone grafts. By basal level analysis the distribution of bone graft types (Fig. 2(B)) differs little from that of the Bergland grading system (Fig. 2(A)) with over 90% of bone grafts categorised as type I or type II. However, when total height is measured the distribution of bone graft types alters considerably (Fig. 2(C)). Normal heights (type I) or heights greater than three quarters of normal (type II) were achieved only in 76% of grafts. This suggests that occlusal (Bergland) or basal level analysis alone is not truly representative of bone graft height.
Although the dental radiograph represents only a two-dimensional analysis of a three-dimensional graft a significant correlation exists between bone support estimates determined by two-dimensional dental radiographs and three-dimensional CT scans.
Thus by height analysis, type I and type II grafts (graft heights of three quarters of normal or greater) are likely to meet the objectives of secondary alveolar bone grafting (Fig. 3, Fig. 4) and such types might indeed be considered successful. Also, by this form of analysis, 24% of grafts were distributed to categories III and IV (Fig. 2(C)). In contrast only 7.5 and 8.5% of grafts were found in these categories when occlusal (Fig. 2(A)) and basal (Fig. 2(B)) levels were analysed, respectively. Thus height analysis categorises and identifies more precisely those patients with low bone graft heights.
Patients with low bone graft heights (type III) may have sufficient bone for arch stabilisation and periodontal and prosthodontic support at least in the short term. However, in the absence of any reported guidelines, low bone graft heights are unlikely to be adequate in those who require orthognathic surgery particularly bilateral cases. With the more frequent use of endosteal implant placement in cleft patients
and given that at least 10 mm of bone depth is required for endosteal implant bone purchase (approximately three quarters the length of the canine root) a bone graft height of three quarters of normal interdental bone height at least is required. These objectives are dependent mostly on absolute graft height. Although ease of orthodontic manipulation is also dependent on bone height it is particularly dependent on the presence of basal bone. A scarcity of cancellous bone and the presence of a cortical plate of bone adjacent to the cleft root apices resist their movement orthodontically and may contribute to apical root resorption
Thus any system of analysis must attempt to measure actual bone height so that the efficacy of bone grafting can be more critically evaluated and patients with insufficient height can be more precisely identified. In addition height measurements should be taken towards the mid-region of the clefts so that any native alveolar bone is excluded from analysis. In those with low bone heights (type III) the basal level becomes significant particularly in those whose desired orthodontic end point cannot be achieved. In addition, in our series at least, loss of height was most often due to a bone deficiency basally rather than occlusally (Fig. 5, Fig. 6). Such deficiency may need further investigation and correction.
Recently a complex system of bone graft analysis has been proposed as an alternative to that of Bergland.
proposes firstly an eight-point scale to map bone thickness on both sides of the cleft midline adjacent to the dental roots. Such bone is often native alveolar bone and cannot be used as a measure of success. Secondly, a nonsequential six-point scale is used to map the position of such bone during the mixed dentition phase despite ongoing canine and premolar root development and eruption. In the absence of a succinct and sequential means of quantification such systems are prone to inter and intra-observer and temporal variability and likely to be of little use in clinical management and audit.
One patient (Fig. 7) in this study had complete graft failure (type IV) and such patients require regrafting.
In order to reduce risk of infection good oral hygiene is essential and to ensure adequate take throughout the entire height of the cleft, bone grafts should not be placed in the presence of gingivitis or nasal infection. In this study loss of height was predominantly due to a deficiency of bone basally and accounts mostly for the redistribution of graft types. Although it is generally accepted that graft take is dependant on the provision of a well mobilised vascular buccal mucoperiosteal flap for closure, given the above, the authors suggest that equal attention should be given to the palatal and nasal floor mucoperiosteal flaps. To achieve an adequate height of bone graft these latter flaps must be sufficiently mobilised posteriorly and superiorly and closed securely without tension. In addition a sufficient quantity of pure cancellous bone graft must be thoroughly condensed posteriorly and superiorly (basally) to the level of the pyriform aperture to restore both the width and full height of the alveolar ridge, respectively. This will also provide support to the alar base and nostril sill regions.
4. Conclusion
The periapical dental radiograph is a cost effective and simple method of assessment of secondary alveolar bone grafts and results in low X-ray exposure. In this study the Bergland scale has been used to grade the basal levels and total heights of bone grafts. The latter represents a true, succinct and consistent measure of bone graft success. It is proposed that this system of assessment is most useful in treatment planning, clinical audit and comparative study. Low bone graft heights (less than three quarters of normal height, type III) are insufficient to fulfil the objectives of alveolar bone grafting particularly in those in whom total orthodontic closure is desired or in those who require implant placement or maxillary osteotomy. In such grafts a record of their basal levels will most often identify the position of bone deficiency and is particularly important when orthodontic manipulation is planned. In collaboration with the orthodontist, prosthodontist and maxillofacial surgeon further investigation may be required in the form of computer-assisted tomography
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