Evaluation and New Classification of Alveolar Bone Dehiscences Using Cone-beam Computed Tomography in vivo

Abstract

Alveolar bone dehiscences, which were “V” shaped defects related the margin of the alveolar bone, were common findings in different populations and decreased bony support of teeth. It was difficult to detect dehiscence during direct clinical examination. All of the previous studies on the prevalence of dehiscences were based on dry human skulls. In the current article, we evaluated the prevalence of dehiscences occurring naturally in a Chinese subpopulation, and prepared a classification of dehiscences using cone-beam computed tomography (CBCT). The high prevalence rate of dehiscences and different characteristics of each category suggest that it would be helpful for clinicians who perform periodontal surgery, endodontic surgery, implant surgery or orthodontic treatment to understand which teeth are most often associated with such bony defects, and to consider the effect of severe dehiscences on their diagnosis and treatment plan.

Full text

361
Int. J. Morphol.,
33(1):361-368, 2015.
Evaluation and New Classification of Alveolar Bone
Dehiscences Using Cone-beam Computed Tomography in vivo
Evaluación y Nueva Clasificación de las Dehicencias del Hueso Alveolar
Mediante Tomografía Computadorizada de Haz Cónico in vivo
Yan Yang
*
; Hui Yang
**
; Hongyin Pan
*
; Jue Xu
*
& Tao Hu
***,****
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam
computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.
SUMMARY: Alveolar bone dehiscences, which were “V” shaped defects related the margin of the alveolar bone, were common
findings in different populations and decreased bony support of teeth. It was difficult to detect dehiscence during direct clinical examination.
All of the previous studies on the prevalence of dehiscences were based on dry human skulls. In the current article, we evaluated the
prevalence of dehiscences occurring naturally in a Chinese subpopulation, and prepared a classification of dehiscences using cone-beam
computed tomography (CBCT). The high prevalence rate of dehiscences and different characteristics of each category suggest that it
would be helpful for clinicians who perform periodontal surgery, endodontic surgery, implant surgery or orthodontic treatment to understand
which teeth are most often associated with such bony defects, and to consider the effect of severe dehiscences on their diagnosis and
treatment plan.
KEY WORDS: Alveolar bone loss; Periodontal disease; Cone-beam computed tomography; Oral surgery.
INTRODUCTION
The periodontium is a unique structure of the human
body that provides support and nutrition for the teeth via
the alveolus, periodontal ligament, cement and supporting
gingiva. Alveolar defects, usually have negative effects
on the prognosis of oral surgeries (Bjerklin & Ericson,
2006).
A dehiscence is defined as a V-shaped defect located
along the alveolar bone margin (BM) toward the apex, and
is located on the buccal or lingual side of a tooth (Leung et
al., 2010). The aetiology of dehiscences can be attributed to
many factors, such as tooth ectopia, root projection,
periodontal inflammation, frenum attachments, root verti-
cal fracture and patient habits (Lustig et al., 2000; Vilchez-
Perez et al., 2009). Dehiscences can be caused by one of the
factors mentioned above or by the interactions of different
factors.
The presence of dehiscences decreases the bony
support for the teeth, which predisposes teeth to gingival
recession, influences the rate and pattern of bone loss and
complicates the outcome of oral surgeries. Alveolar bone
with a dehiscence usually lacks a supporting layer of bone
marrow, and depends on the periosteum and periodontal
connective tissue for adequate nourishment and blood supply.
Therefore, surgeries or treatment that remove or damage the
periosteum, such as mucogingival surgery and endodontic
surgery, will lead to even further resorption of the thin
overlying plate of bone.
Dehiscences are present in different populations, with
a reported prevalence ranging from 3.2% to 7.1% (Table I).
Because of the high occurrence rate and undesirable effects of
dehiscences, it is important that the dentists who perform oral
surgeries or treatments and surgery have knowledge of
the
*
Doctoral Candidate, Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology,
Sichuan University, Sichuan, China.
**
Lecturer, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Sichuan, China.
***
Professor, Department of Operative Dentistry and Endodontics, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan
University, Sichuan, China.
****
Professor, Chair of Department of Preventive Dentistry, State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan
University, Sichuan, China.

362
effects of dehiscences on disease diagnosis and prognosis and
on treatment planning in daily clinical practice. Considering
the fact that bone dehiscences are covered by soft tissues, they
are not visible to the naked eye and are usually undetectable.
Occurring on the buccal or lingual side, dehiscences also es-
cape routine radiographic diagnosis because of the overlapping
images of the surrounding bony tissues. Hence, previous
studies that investigated the prevalence of dehiscences were
based merely on dry human skulls and on flap surgery on
cadaver
s via direct evaluation (Rupprecht et al., 2001). The
establishment of an accurate diagnosis of dehiscences without
destroying soft tissues was reported only recently: cone-beam
computed tomography (CBCT) was used to evaluate
dehiscences in patients during orthodontic treatments (Janson
et al., 2003). The accuracy of CBCT for identifying and
measuring dehiscences has been confirmed in studies of
artificially created alveolar bone defects (de-Azevedo-Vaz et
al., 2013). Hence, CBCT has advantages for the evaluation of
naturally occurring bony dehiscences in vivo (Ising et al., 2012).
Thus, the aim of this paper is to evaluate the prevalence,
distribution and severity of dehiscences that occur naturally
in humans by improving the method of dehiscence
identification through CBCT and making a classification of
dehiscences using a novel system based on the findings.
MATERIAL AND METHOD
Sample collection. Three hundred sixty four CBCT images
from patients who received CBCT during routine
examination were obtained from the Department of Oral
Radiology, West China Hospital of Stomatology, Sichuan
University, China. The study was approved by the Ethics
Committee of the West China Hospital of Stomatology, and
informed consent was obtained from the patients. CBCT
images that included mixed dentition, single jaw, less than
10 teeth per jaw, metal prostheses, obvious trauma or tumor
or cyst in the alveolar process, as well as those without a
view of the entire tooth and surrounding alveolar bone, were
excluded from the study. Third molars were also excluded.
Finally, a total of 108 patients (2574 teeth) were obtained
(Table II).
Radiographic technique. The CBCT images were produced
at 80 kV and 5.0 mA using a 3D Accuitomo scanner (J.
Morita, Kyoto, Japan), with the voxel size of the images set
at 0.125 mm and the slice thickness set at 1 mm. CBCT was
performed by an experienced oral radiologist using the
manufacturer’s protocol and radiographic standards to
guarantee the quality of the images and to minimize the
Table I. Retrospection of the literature on prevalence of bone dehiscence.
Max. indicates Maxillary, and Man. indicates Mandible. *= Means studies on dehiscences occurred during orthodontic treatment. None of the studies
except the current one using CBCT investigated the prevalence of dehiscences in ethnic populations.
Studies Population Method
Samples
(teeth)
Prevalence Criteria used for dehiscence
Davies et al. (1974) British Dry Skull 398
(4143)
5.4% The crest of the buccal bone was at least 4 mm
apical to the crest of the interproximal bone.
Rupprecht et al.
(2001)
American Dry Skull 146
(3315)
4.1% Davies et al. (1974)
Edel (1981) Bedouin Dry Skull Max. 37
Man. 50
Max. 2.1%
Man. 5.5%
Davies et al. (1974)
Abdelmalek et al.
(1973)
Egyptian Dry Skull Max. 61
Man. 93
Max. 8.19%
Man. 21.5%
The absence of the alveolar cortical plate, in some
cases extending more than half of the root length.
Larato (1970) Mexican Dry Skull 108 3.2% Not in detail.
Urbani et al. (1991) Italian Dry Skull 90 Max. 6.3%
Man. 6.46%
Not in detail.
Tal (1983) South Dry Skull Man. Man. 7.1% Not in detail.
Volchansky & Vieira
(1981)
South
African
Dry Skull Max.
Man. 43
Max. 5.6%
Man. 6.5%
Not in detail.
Yagci et al. (2012)* --- CBCT --- --- The alveolar bone height more than 2 mm from
the cement-enamel junction.
Evangelista et al.
(2010)*
--- CBCT --- --- The lack of facial or lingual cortical plates, which
results in exposing the cervical root surface and
Leung et al. (2010)* --- CBCT --- --- A V-shaped defect along the BM, with the
alveolar bone height 3 mm or greater to the CEJ.
Current Study Chinese CBCT 108
(2574)
8.51%
Max. 5.37%
Man.
11.55%
A V-shaped defect along the alveolar bone margin
apically with the lack of the margin, locates on the
buccal or lingual aspect of a tooth.
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

363
radiation dosage delivered to the patients. Three-dimensio-
nal (3D) reconstructions were performed for each patient
based on the CBCT images.
Evaluation of images. All of the analysis and 3D
reconstructions of the CBCT data were performed using the
in-built software (i-Dixel One Volume Viewer, Ver. 1.5.0)
and viewed on a 32-in Sony LCD screen with a resolution
of 1920 ´ 1080 pixels in a dim light room.
The 3D volume-rendering mode was used to dis-
play the CBCT images to identify dehiscences in the
buccal/lingual alveolar bone (Fig. 1A). Any V-shaped
alveolar bony defect involving the bone margin and
pointing to the root apex was identified as a dehiscence.
After a dehiscence was diagnosed, the tooth root was
evaluated in 2D cross-sectional images (Fig. 1B and 1C).
First, the coronal (mesiodistal) plane of each tooth, which
was determined by a line connecting the midpoints of the
mesial and distal marginal ridges, was placed perpendicu-
lar to the horizontal plane, and the alveolar bone height
was measured from the cement–enamel junction (CEJ) to
the alveolar crest (AC). The height was represented by
HMD (the height of the CEJ–AC in the mesiodistal plane)
(Fig. 1B). Subsequently, the sagittal (buccolingual) pla-
nes were placed perpendicular to the horizontal plane, and
an alveolar defect was recorded when there was no cortical
bone around the root in at least three consecutive views.
The linear height of the CEJ to the AC in the buccolingual
plane, which was represented by H
BL
, was measured in
three adjacent sagittal planes through the dehiscence, and
the maximum height value was chosen (Fig. 1C). Finally,
the height of the dehiscence (H
D
) was equal to HBL minus
HMD (D
H
= H
BL
– H
MD
). D
H
>0 indicated the existence of
an alveolar bone dehiscence, whereas D
H
≤0 indicated a
false-positive result of the 3D view.
Moreover, to distinguish dehiscences with different
clinical manifestations in the present study, alveolar bone
dehiscences were categorized into the following types and
divisions, using a no
vel classification system based on the
height of the dehiscence and other accompanying alveolar
bone defects. All of these classifications were established
using the sagittal planes (Fig. 2).
Class I: simple dehiscences located on one side (buccal or
lingual) of the tooth, without any other alveolar bone defects.
Division I: dehiscences of the coronal one-third of the root.
Division II: dehiscences of the middle one-third of the root.
Division III: dehiscences of the apical one-third of the root,
without the involvement of the apical foramen.
Reasons for CBCT scanning n Percentage
Assessment for implant surgery 49 45.37
Jaw disease (tumor or cyst) 14 12.96
Facial trauma 11 10.19
Assessment for orthognathic surgery 9 8.33
Assessment for orthodontic 8 7.41
Maxillary sinusitis 4 3.70
Temporal-mandibular joint disease 4 3.70
Salivary gland disease 4 3.70
Cleft lip and palate 3 2.78
Nasopharyngeal carcinoma 2 1.85
Total 108 100
Table II. Samples included for evaluation.
Fig. 1. CBCT 3D view and 2D views showing dehiscences. A, the 3D view on the buccal side of
the tooth root. The red circle denotes the dehiscence. B, the mesial-distal view of the alveolar.
C, the buccolingual cross-sectional view of the dehiscence. CEJ= cement–enamel junction.
AC= alveolar crest. H
MD
= the CEJ–AC of the inter-proximal alveolar. H
BL
= the CEJ–AC of the
dehiscence.
In Class I dehiscences, the
tooth root was divided into three
equal portions, from the CEJ to
the root apex. The coronal,
middle and apical one-third of the
root were classified as Division
I, Division II and Division III,
respectively.
Class II: dehiscences with
periapical bone defects located on
one side (buccal or lingual) of the
tooth. Division I: dehiscences of
the whole root, with the
involvement of the apical fora-
men. Division II: dehiscences
accompanied by periapical
lesions. A periapical lesion was
defined as a radiolucency
associated with the apical part of
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

364
a root that exceeded at least twice the width of the periodontal
ligament space (Lofthag-Hansen et al., 2007). Division III:
dehiscences with fenestrations surrounding the root surface
apically. Fenestration was identified as a defect in the alveolar
bone without involvement of the alveolar margin (Pan et
al., 2014).
Class III: dehiscences locating on both sides of the tooth.
The classification is established according to the more severe
side, referring to the divisions of Class I and Class II.
To distinguish Class I Division III from Class II
Division I, more than three sagittal planes were used to detect
the relationship between the margin of the defect and the
apical foramen.
Two observers evaluated the teeth separately using
the same criteria. When they disagreed, the third observer
was introduced to evaluate the images with them and pro-
duce final consensus. Before the study, the three observers
were trained in the same diagnostic criteria for the diagno-
sis of dehiscence and the details of this study, to improve
baseline consistency.
Statistical analyses. Data analysis was conducted with
Statistical Package for the Social Sciences (SPSS, version
18.0, Chicago, IL, USA) and the samples were confirmed
with Gaussian distribution and homogeneity of variance.
The prevalence of dehiscences in different teeth, different
jaws, different sexes and different ages was evaluated using
a regression analysis. One-way ANOVA followed by post-
Turkey or Bonferroni multiple comparison tests were used
to analyze the differences in different teeth and different
ages, student t test for comparison the data of different
jaws and different sex. Mean values with a difference of
P<0.05 were considered statistically significant.
RESULTS
The CBCT images of 2574 teeth in 108 patients were
examined. Alveolar bone dehiscences were associated with
8.51% of all teeth (Table III), and at least one dehiscence
was identified in 75% of all patients.
The intra-oral distribution of these defects is shown
in Table IV. The distributions of dehiscences according to
jaw and tooth type were calculated; 11.55% of dehiscences
were observed on mandibles, whereas 5.37% of dehiscences
were observed on maxillaries. The teeth that were most
commonly associated with dehiscences were the first
mandibular premolars (37.56%) and the mandibular canines
(13.49%) (P = 0.00). The first maxillary molars (10.08%),
second mandibular premolars (9.95%) and first maxillary
premolars (8.65%) followed, albeit without statistically
significant differences between any two of these three groups.
Women had more alveolar bone dehiscences (10.8% vs.
7.03%) than men (P= 0.00) (Table III).
Most of the dehiscences were found in the buccal
alveolar plates (96.80%), and only 5.02% were found in the
palatal or lingual side.
The dehiscences were classified into three types. The
prevalence of dehiscences according to the different
classifications is listed in Table V. Class I was the most frequent
type (86.03%), followed by Class II (7.31%) and Class III
(6.39%). In Class I, and considering the specific part of the
root involved, Division II was the most common subtype
(42.47%), followed by Division I (26.03%) and Division III
(17.35%). In Class II, which includes periapical bone defects,
the most common type was Division III (5.94%), followed by
Division I (0.91%) and Division II
(0.46%). (P= 0.00)
Fig. 2. Diagrammatic illustration indicating the classification of dehiscences based on the mesial-distal views. The red arrows indicate
the alveolar dehiscences, the red solid triangles indicate the root fenestrations and the triangles denote the periapical lesions.
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

365
DISCUSSION
As a routine dental radiography modality, CBCT has
the potentia
l to identify periodontal and alveolar defects
without distortion, which is seen commonly in a panoramic
radiograph. Compared with conventional radiography,
CBCT enables the understanding of the morphology and
the measuring of the size of alveolar defects. Previous
studies (Enhos et al., 2012; Evangelista et al., 2010; Yagci
et al., 2012) have used CBCT to measure the alveolar bone
and detect dehiscences via axial and cross-sectional
imaging. Leung et al., evaluated the accuracy and reliability
of CBCT 3D constructions for measuring alveolar bone
height and defects via direct measurements in 3D images.
To facilitate the investigation of a large number of samples,
we improved the method by combining the CBCT 3D
constructions with 2D sections. Preliminary screenings
were performed according to the 3D images. Subsequently,
the 2D sections were used to exclude false-positive results,
including thin bone coverage and horizontal resorptions
and fenestrations, which were mistaken for dehiscences
on 3D views. Finally, a definitive diagnosis and
classification were established.
In previous studies on dehiscence that used CBCT,
the method applied was usually direct measurements of CEJ–
AC (Leung et al.), which was feasible for samples without
horizontal resorption. However, the absorption of the
alveolus would lead to false-positive results. Therefore, we
improved the method by excluding the effect of horizontal
resorption (Fig. 1).
Among the 2574 teeth examined, 8.6% had alveolar
bone dehiscences. This was somewhat higher than the 3.2%
to 7.1% reported in the previous literature, which investigated
dry human skulls among various ethnic groups (Table?).
There are various explanations for this difference, including
the racial differences suggested by most investigators, the
various criteria used for the diagnosis of dehiscences,
discrepancies between dry skulls and CBCT images, etc.
Sex No. n Prevalence (%)
Male 1565 110 7.03
Female 1009 109 10.80
Total 2574 219 8.51
Tooth type 1 2 3 4 5 6 7 Total
Max. No. 190 205 207 208 200 129 128 1267
n 671518913068
Prevalence 3.16 3.41 7.25 8.65 4.50 10.08 0 5.37
Man. No. 209 215 215 213 201 135 119 1307
n 6529 8020101151
Prevalence 2.87 2.33 13.49 37.56* 9.95 7.41 0.84 11.55
Type n Percentage (%)
Class I DI 57 189 26.03 86.30
DII 93 42.47 ---
DIII 38 17.35 ---
Class II DI 2 16 0.91 7.31
DII 1 0.46 ---
DIII 13 5.94 ---
Class III --- 14 14 6.39 6.39
Table III. Distribution of dehiscences according to sex.
No.= number of teeth calculated. n= number of teeth with
dehiscences.
Table IV. Distribution of dehiscences according to jaw and tooth type.
*= Significant difference from any other group, P<0.05. No.= number of teeth calculated. n= number of
teeth with dehiscences. Max. indicates Maxillary and Man. indicates Mandible.
Table V. Distribution of dehiscences according to classification.
n= number of teeth with dehiscence.
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

366
Rupperecht et al. and Tal (1983) indicated that the
different diagnostic criteria used by different authors may
have had an additional effect on their results, making
consensus difficult to reach. The definitions of dehiscence
varied from a deficiency in alveolar bone resulting in the
absence of alveolar cortical plate to a denuded root. The
dimensions of dehiscences ranged from 1 mm to 4 mm or
more from CEJ to AC. These differences in definitions and
criteria may explain some of the variability in the distribution
and prevalence of dehiscences observed among studies.
Therefore, according to previous studies, we have
emphasized the main characteristics of all the dehiscences,
which could be described as a V-shaped defect located along
the alveolar bone margin, together with the denuded areas
involving the alveolar bone margin. The V shape is critical
for the differentiation of dehiscence from horizontal bone
loss and U-shaped defects. The absence of the bone margin
is used to distinguish dehiscence from fenestration, which
is a window-like defect of the alveolar bone without the
involvement of the alveolar margin (Pan et al.). Hence, in
our study, an alveolar bone dehiscence was defined as a bony
defect of the alveolar unit that appears as a V-shaped defect
along the alveolar bone apically, lacks a margin and is located
on the buccal or lingual side of a tooth. This definition was
a combination of all previous definitions, and was not limited
by the CEJ–AC length of the defect. As a result, it may lead
to a higher prevalence of dehiscences than that reported in
previous studies.
Moreover, as the alveolar bone plates in dried skulls
may be physically damaged after exposure to soil, air and
dissection, which may destroy the “V” shape of dehiscences,
the prevalence of this phenomenon in those studies might
be different from that observed in this in vivo study. Different
ethnic backgrounds, preservation methods and acquisition
methods would also affect the extent of bone erosion.
In the present study, dehiscences were more frequent
in the mandible than in the maxilla. The most commonly
associated teeth were the first mandibular premolars and
mandibular canines. These findings were in agreement with
those of previous reports (Rupprecht et al.; Davies et al.,
1974), and indicated that more attention should be paid to
the teeth mentioned above. Alveolar defects were found
frequently on the buccal or labial surfaces in this study and
in previous ones (Rupprecht et al.; Edel, 1981). In addition,
the defects (5.02%) were also found on the lingual or palatal
aspect of the root. These results are consistent with the
investigations of Rupperecht et al., and Evangelista et al.
Dehiscences occurred more frequently in women than
in men. However, only one other study reported that
dehiscences were more frequent in women, without statistical
support (Rupprecht et al.). Although this could be attributed
to the thinner alveolar bone of women, further studies are
needed to assess this issue. In the present study, dehiscences
were found most frequently on mandibular first premolars
in all age groups, which was consistent with the study
reported by Davies et al.. However, there was no statistically
significant difference between any two age groups. This may
indicate that age is not an important cause of dehiscences.
According to the literature, different criteria were
used to detect dehiscences, and little information about the
size or type of dehiscence was provided. Mild dehiscences
may exist, without symptoms. However, severe dehiscences
can result in further periodontal breakdown and aesthetic
complications (Cardaropoli & Gaveglio, 2007). According
to the new classification suggested in this study, alveolar
bone dehiscences were classified into three classes,
depending on the size of the dehiscences or whether the
dehiscences were accompanied by any other alveolar bone
defect.
In Class I, simple dehiscences that occurred on one
side of the teeth were then sorted into three divisions,
depending on the range of the dehiscences. It was reported
that the root surface located between the gingival margin
and the alveolar bone margin is attached tightly by a long
connective tissue (Löst, 1984). Hence, Class I Division I
(26.03%), which was the mildest condition among all the
dehiscences, may have no symptoms or signs. Class I
Division II (42.47%) may have some signs of gingival
recession, leading to various degrees of aesthetic problems,
but may be painless or lack loosening because of the support
from the bone and long connective tissue. The three divisions
accounted for most of the dehiscences, which implies that
most of the patients with dehiscences have no chief complaint
or obvious signs. Class I Division III may have some
aesthetic or lingual-buccal loosening problems, albeit not
severe because of the remaining support from the connective
tissue and the bone. Dehiscences located on both sides of
the tooth were classified as Class III, whose effect will be
determined by the two defects.
In the present study, dehiscences with periapical
lesions were also detected; these may lead to pathological
changes. Class II Division I included dehiscences of the
whole root involving the root foramen, which may yield no
pathological changes for a long time because of the support
and nutrition from the connective tissue. However, once
inflammation or trauma occurs in the teeth, severe effects,
such as tooth mobility, retrograde pulpitis or loss of the tooth,
will occur. Class II Division II included dehiscences with
any periapical bone defect combined with inflammation,
which were often caused by pulpitis. In cases with spreading
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

367
of the periapical lesion, it is easy to break through the bone
between the dehiscence and periapical lesion, leading to
periodontal– endodontic combined lesions. Class II Division
I and Division II represented only three cases among the
teeth studied here. It is assumed that most of the teeth with
these classes of dehiscences could not be included in the
classification because of natural loss or extraction in older
patients. Class II Division III represented the combination
of dehiscence and fenestration, and is complex. A
combination with the classification of fenestration provided
in the study of Pan et al., should be considered under specific
conditions.
During mucogingival flap surgery, the root surface
should not be exposed, and an adequate blood supply to the
soft tissue coverage of the defect should be ensured (Yagci
et al.). Dehiscences are sometimes located in areas with a
relatively thin mucosa, which may result in insufficient blood
supply to the flap. Therefore, a full-thickness flap is
suggested to maximize blood supply to the overlying tissue
at the defect site.
Kim & Kratchman, (2006) indicated that deficiency
of marginal bone tissue has a significant effect on the
prognosis of endodontic microsurgery. A buccal bone plate
that covered the teeth for >3 mm was expected to yield a
favorable outcome. Once an alveolar bone defect is found, a
comprehensive treatment plan including endodontic
microsurgery is suggested.
Spray et al. (2000) indicated that an alveolar bone
wall with a thickness greater than 2 mm was crucial for the
successful long-term outcomes of implants. Merheb et al.
(2010) reported that a terminal dehiscence defect would
influence the stability of the implant. For patients with a
thin alveolar wall or bone defect, a thorough examination
and adjunctive bone augmentation are recommended (Zekry
et al., 2013). Considering the fact that peri-implant bone
defects are not visible to the naked eye and traditional
radiography, CBCT is of paramount importance to detect
such defects (de-Azevedo-Vaz et al.).
The possible presence of dehiscences also requires
attention before orthodontic treatment. Gingiva
augmentation prior to orthodontic therapy should be
considered for all teeth with a gingival complex. Severe
dehiscences, on the other hand, can be partly improved by a
combination of guided tissue regeneration and connective
tissue graft. This is of even greater importance for teeth in
which clinical examination or CBCT images indicate the
presence of underlying dehiscences.
There was a lack of report on clinical signs of
dehiscences in the present literature. Combining dehiscences
detected from the existing CBCT images with the clinical
manifestations would make clinically detecting of dehiscence
more targeted. It will be helpful to avoid the excessive
application of CBCT through prejudgment of the severity
of dehiscence type clinically, which is the next research
purpose of this subject.
ACKNOWLEDGEMENTS
This work was supported by the Key Clinical
Program of the Ministry of Health of China. The funding
body had no role in the study design, data collection and
analysis, decision to publish or preparation of the manuscript.
We also gratefully thank Zhili Zhao, PhD, School and Hos-
pital of Stomatology, Wuhan University, Wuhan, China for
valuable suggestions and enthusiastic support.
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluación y nueva clasificación de las dehicencias del hueso alveolar mediante
tomografía computadorizada de haz cónico. Int. J. Morphol., 33(1):361-368, 2015.
RESUMEN: Las dehiscencias óseas alveolares, con forma de "V" en el margen del hueso alveolar, son hallazgos comunes en
diferentes poblaciones y provocan una disminución del soporte óseo de los dientes. La dehiscencia fue difícil de identificar durante la
exploración clínica directa. Todos los estudios anteriores sobre la prevalencia de dehiscencia se basaron en cráneos humanos secos. En
el presente artículo, se evaluó la prevalencia de dehiscencia natural ocurrido en una subpoblación de China. Realizamos una clasificación
de las dehiscencias mediante tomografía computarizada cone-beam (TCCB). La alta prevalencia de dehiscencias y las diferentes carac-
terísticas de cada categoría sugieren que esta clasificación sería de gran ayuda para los médicos que realizan cirugía periodontal, endodóntica,
cirugía de implantes o tratamiento de ortodoncia, permitiendo informar sobre que dientes están más frecuentemente asociados con tales
defectos óseos, y poder considerar los efectos severos de las dehiscencias severas en el diagnóstico y el plan de tratamiento.
PALABRAS CLAVE: Pérdida de hueso alveolar; Enfermedad periodontal; Tomografía computadorizada de haz cónico;
Cirugía oral.
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.

368
REFERENCES
Abdelmalek, R. G. & Bissada, N. F. Incidence and distribution of alveolar
bony dehiscence and fenestration in dry human Egyptian jaws. J.
Periodontol., 44(9):586-8, 1973.
Bjerklin, K. & Ericson, S. How a computerized tomography examination
changed the treatment plans of 80 children with retained and
ectopically positioned maxillary canines. Angle Orthod., 76(1):43-
51, 2006.
Cardaropoli, D. & Gaveglio, L. The influence of orthodontic movement
on periodontal tissues level. Semin. Orthod., 13(4):234-45, 2007.
Davies, R. M.; Downer, M. C.; Hull, P. S. & Lennon, M. A. Alveolar
defects in human skulls. J. Clin. Periodontol., 1(2):107-11, 1974.
de-Azevedo-Vaz, S. L.; Vasconcelos, Kde. F.; Neves, F. S.; Melo, S. L.;
Campos, P. S. & Haiter-Neto, F. Detection of periimplant fenestration
and dehiscence with the use of two scan modes and the smallest
voxel sizes of a cone-beam computed tomography device. Oral Surg.
Oral Med. Oral Pathol. Oral Radiol., 115(1):121-7, 2013.
Edel, A. Alveolar bone fenestrations and dehiscences in dry Bedouin
jaws. J. Clin. Periodontol., 8(6):491-9, 1981.
Enhos, S.; Uysal, T.; Yagci, A.; Veli, I.; Ucar, F. I. & Ozer, T. Dehiscence
and fenestration in patients with different vertical growth patterns
assessed with cone-beam computed tomography. Angle Orthod.,
82(5):868-74, 2012.
Evangelista, K.; Vasconcelos, Kde. F.; Bumann, A.; Hirsch, E.; Nitka,
M. & Silva, M. A. Dehiscence and fenestration in patients with
Class I and Class II Division 1 malocclusion assessed with cone-
beam computed tomography. Am. J. Orthod. Dentofacial Orthop.,
138(2):133.e1-7, 2010.
Ising, N.; Kim, K. B.; Araujo, E. & Buschang, P. Evaluation of
dehiscences using cone beam computed tomography. Angle Orthod.,
82(1):122-30, 2012.
Janson, G.; Bombonatti, R.; Brandão, A. G.; Henriques, J. F. & de Freitas,
M. R. Comparative radiographic evaluation of the alveolar bone
crest after orthodontic treatment. Am. J. Orthod. Dentofacial
Orthop., 124(2):157-64, 2003.
Kim, S. & Kratchman, S. Modern endodontic surgery concepts and
practice: a review. J. Endod., 32(7):601-23, 2006.
Larato, D. Alveolar plate fenestrations and dehiscences of the human
skull. Oral Surg. Oral Med. Oral Pathol., 29(6):816-9, 1970.
Leung, C. C.; Palomo, L.; Griffith, R. & Hans, M. G. Accuracy and
reliability of cone-beam computed tomography for measuring
alveolar bone height and detecting bony dehiscences and
fenestrations. Am. J. Orthod. Dentofacial Orthop., 137(4
Suppl.):S109-19, 2010.
Lofthag-Hansen, S.; Huumonen, S.; Gröndahl, K. & Gröndahl, H. G.
Limited cone-beam CT and intraoral radiography for the diagnosis
of periapical pathology. Oral Surg. Oral Med. Oral Pathol. Oral
Radiol. Endod., 103(1):114-9, 2007.
Löst, C. Depth of alveolar bone dehiscences in relation to gingival
recessions. J. Clin. Periodontol., 11(9):583-9, 1984.
Lustig, J. P.; Tamse, A. & Fuss, Z. Pattern of bone resorption in vertically
fractured, endodontically treated teeth. Oral Surg. Oral Med. Oral
Pathol. Oral Radiol. Endod., 90(2):224-7, 2000.
Merheb, J.; Coucke, W.; Jacobs, R.; Naert, I. & Quirynen, M. Influence
of bony defects on implant stability. Clin. Oral Implants Res.,
21(9):919-23, 2010.
Pan, H. Y.; Yang, H.; Zhang, R.; Yang, Y. M.; Wang, H.; Hu, T. & Dummer,
P. M. Use of cone-beam computed tomography to evaluate the
prevalence of root fenestration in a Chinese subpopulation. Int.
Endod. J., 47(1):10-9, 2014.
Rupprecht, R. D.; Horning, G. M.; Nicoll, B. K. & Cohen, M. E.
Prevalence of dehiscences and fenestrations in modern American
skulls. J. Periodontol., 72(6):722-9, 2001.
Spray, J. R.; Black, C. G.; Morris, H. F. & Ochi, S. The influence of
bone thickness on facial marginal bone response: stage 1 placement
through stage 2 uncovering. Ann. Periodontol., 5(1):119-28, 2000.
Tal, H. Alveolar dehiscences and fenestrae in dried South African Negro
mandibles. Am. J. Phys. Anthropol., 61(2):173-9, 1983.
Vilchez-Perez, M. A.; Fuster-Torres, M. A.; Figueiredo, R.; Valmaseda-
Castellón, E. & Gay-Escoda, C. Periodontal health and lateral lower
lip piercings: a split-mouth cross-sectional study. J. Clin.
Periodontol., 36(7):558-63, 2009.
Volchansky, A. & Vieira, E. Alveolar dehiscence and fenestration in dried
South Africa Negro maxillae. J. Dent. Aorthodontic treatment to
understand which teeth are most often associated with such bony
defects, and to consider the effect of severe dehiscences on their
diagnosis and treatment plan. J. Dent. Assoc. S. Afr., 36(10):701-4,
1981.
Yagci, A.; Veli, I.; Uysal, T.; Ucar, F. I.; Ozer, T. & Enhos, S. Dehiscence
and fenestration in skeletal Class I, II, and III malocclusions assessed
with cone-beam computed tomography. Angle Orthod., 82(1):67-
74, 2012.
Zekry, A.; Wang, R.; Chau, A. C. & Lang, N. P. Facial alveolar bone
wall width - a cone-beam computed tomography study in Asians.
Clin. Oral Implants Res., 25(2):194-206, 2014.
Correspondence to:
Hu Tao
West China Hospital of Stomatology
State Key Laboratory of Oral Diseases
Sichuan University
14#, 3rd section, Renmin South Road
Chengdu 610041
Sichuan
CHINA
Email: hutao@scu.edu.cn
Received: 18-09-2014
Accepted: 30-12-2014
YANG, Y.; YANG, H.; PAN, H.; XU, J. & HU, T. Evaluation and new classification of alveolar bone dehiscences using cone-beam computed tomography in vivo. Int. J. Morphol., 33(1):361-368, 2015.