stomaeduj-2-2020-article-2

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                    PEDODONTICS
                    DENTAL FINDINGS OF PERSONS WITH OSTEOGENESIS
Original Articles
                    IMPERFECTA IN VIETNAM
                    Minh Son Nguyen1a* , Mare Saag2b, Ho Duy Binh 3c , Katre Maasalu4d , Sulev Kõks 5e , Aare Märtson6e ,
                    Thi Thuy Le7c, Triin Jagomägi8f
                    1
                      Faculty of Odonto-Stomatology, Danang University of Medical Technology and Pharmacy, Danang, Vietnam
                    2
                      Institute of Dentistry, University of Tartu, Tartu, Estonia
                    3
                      Hue University of Medicine and Pharmacy, Hue University, Hue, Vietnam
                    4
                      Department of Traumatology and Orthopedics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia, Clinic of Traumatology and Orthopedics,
                    Tartu University Hospital, Tartu, Estonia
                    5
                      Centre for Comparative Genomics, Murdoch University, Perth, Australia
                    6
                      Department of Traumatology and Orthopedics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia, Clinic of Traumatology and Orthopedics,
                    Tartu University Hospital, Tartu, Estonia
                    7
                      Faculty of Laboratory Medicine, Danang University of Medical Technology and Pharmacy, Danang, Vietnam
                    8
                      Institute of Dentistry, University of Tartu, Tartu, Estonia

                    a
                      DDS, PhD; e-mail: minhson1883@gmail.com; ORCIDiD: https://orcid.org/0000-0001-9568-596X
                    b
                      DDS, PhD, Professor; e-mail: mare.saag@ut.ee
                    c
                      MD, PhD, e-mail: binhthuybi@yahoo.com; ORCIDiD: https://orcid.org/0000-0003-1925-4601
                    d
                      MD, PhD, Associate Professor; e-mail: katre.maasalu@kliinikum.ee; ORCIDiD: https://orcid.org/0000-0002-9428-0116
                    e
                      MD, PhD, Professor; e-mail: sulev.koks@perron.uwa.edu.au; ORCIDiD: https://orcid.org/0000-0001-6087-6643
                    f
                      MD, PhD, Professor; e-mail: aare.martson@kliinikum.ee; ORCIDiD: https://orcid.org/0000-0003-4857-484X
                    g
                      MD, PhD; e-mail: ltthuy@dhktyduocdn.edu.vn
                    h
                      DDS, PhD, Associate Professor; e-mail: triin.jagomagi@ut.ee; ORCIDiD: https://orcid.org/0000-0003-4023-6256


                    ABSTRACT                                                                                https://doi.org/10.25241/stomaeduj.2020.7(2).art.2

                    Background Osteogenesis imperfecta (OI) is the collective term for a heterogeneous group of connective
                    tissue syndromes. The aim of the current study is to describe dental characteristics, including dentinogenesis
                    imperfecta (DGI), dental wear, occlusal features, and dental caries experience of Vietnamese persons with OI.
                    Methods The sample consisted of 74 individuals with OI classified into type I (n=25), type III (n=24), and type
                    IV (n=25). All participants were examined for DGI through the evaluation of intrinsic color variation, dental
                    wear using Hooper’s index, occlusal features (including Angle’s classification, overjet, overbite, crossbite) and
                    dental caries experience by using the dmft/DMFT index.
                    Results DGI was found in 62.2% of the sample and was significantly related to OI type III and type IV (p=0.019).
                    Dental wear occurred in 36.5% and was equivalent among OI types. Angle Class III malocclusion was more
                    prevalent in type III (66.7%) and type IV (54.5%) than in type I (37.5%). High prevalence of reverse overjet
                    (60.3%), posterior crossbite (32.2%), and missing teeth (23.3%) were found in the OI sample. The mean dmft/
                    DMFT score was 3.0/2.2. The dental findings related to dental wear, occlusal features, and dental caries did
                    not show significant differences among type I, III, and IV.
                    Conclusion There was a high prevalence of DGI and dental wear in the Vietnamese OI sample. Occlusal
                    features were related to a high prevalence of class III malocclusion, overjet, open bite, posterior crossbite,
                    and missing teeth. Dental caries experience of persons with OI was at a moderate level.

                    KEYWORDS
                    Dental Care for Disabled; Dentinogenesis Imperfecta; Dental Occlusion; Osteogenesis Imperfecta.




                                  OPEN ACCESS This is an Open Access article under the CC BY-NC 4.0 license.
                                  Peer-Reviewed Article
                        Citation: Nguyen MS, Saag M, Duy BH, Maasalu K, Kõks S, Märtson A, Le TT, Jagomägi T. Dental findings of persons with osteogenesis imperfecta in
                        Vietnam. Stoma Edu J. 2020;7(2):94-101.
                        Received: March 10, 2020; Revised: April 02, 2020; Accepted: May 06, 2020; Published: May 08, 2020
                        *Corresponding author: Minh Son Nguyen, DDS, PhD, Faculty of Odonto-Stomatology, Danang University of Medical Technology and Pharmacy
                        99 Hung Vuong street, Danang City, Vietnam
                        Tel/Fax: +84-983-060-321; e-mail: minhson1883@gmail.com
                        Copyright: © 2020 the Editorial Council for the Stomatology Edu Journal.




     94             Stoma Edu J. 2020;7(2): 94-101                                                                         pISSN 2360-2406; eISSN 2502-0285
Osteogenesis imperfecta in Vietnam
                                                                                                                           www.stomaeduj.com



1. INTRODUCTION                                              was based on evaluating color variation, including




                                                                                                                         Original Articles
                                                             lightness level, saturation, and hue of teeth, using
Osteogenesis imperfecta (OI) is the collective term          the Vita System 3D-Master.
for a heterogeneous group of connective tissue               The system consists of six lightness level groups
syndromes. Seventeen mutated genes have been                 from 0 to 5 (0=lightest, 5=darkest), five grades of
found related to OI syndromes [1,2]. The mutation            color saturation (chroma) with a given score of 1,
incidence varies in different populations from               1.5, 2, 2.5 and 3, and three levels of hue (L=yellowish,
1/20,000 to 1/10,000 OI cases [3–5].                         M=intermediate hue, R=reddish). In the current
The clinical classification of OI includes five types        study, the lightness level was divided into grades
(type I–V) [2,6]. Type I is a mild phenotype with            of lightness (score 0–2) and darkness (score 3–5);
dominantly inherited OI and blue sclerae; type II            chroma was grouped into low saturation (score 1–2)
is related to perinatal lethality; type III results in       and high saturation (score 2.5–3).
progressive deformity throughout the lifespan; type          Tooth shades were determined in daylight in 5–7
IV is similar to type I, but sclerae are normal; and type    seconds. In our study, DGI was confirmed by intrinsic
V has mesh-like bone appearance due to calcification         color variation with teeth that were darker, had high
in inter-osseous membranes. In clinical studies, types       color saturation and displayed a reddish hue.
I, III and IV are often mentioned to describe the clinical
features of living individuals with OI syndrome.             2.3. Measurement of dental wear
Collagen mutation may influence the dental-facial            A dental impression was taken for pouring a dental
structures of individuals with OI. Previous studies          cast to measure tooth wear using a millimeter probe.
indicated that more than 50% of individuals with OI          Tooth wear was evaluated based on Hopper's index
had class III malocclusions [7-9]. The OI syndromes          [15]. A six-point scale (0=no wear, 5=the most severe)
cause not only maxillary deficiencies but also               was used to identify a tooth as having incisal/cuspal
hypodontia [8,10]. Dentinogenesis imperfecta (DGI)           wear. The level of tooth wear was grouped into no/
and dental abnormalities are also observed in intra-         mild and moderate/severe levels.
oral and radiologic examination of persons with OI,
such alterations may result in premature wear of             2.4. Examination of dental caries
dental structure [10-13]. This suggests that OI has an       The dental caries experience of persons with OI was
impact on many oral conditions. Because it is a rare         recorded using the Decayed, Missing and Filled Teeth
disease, many OI studies focus on finding genetic            index for permanent teeth (DMFT) and for primary
mutations and on the treatment of bone fractures.            teeth (dmft). A decayed tooth was registered as
There are still gaps in the scientific literature about      presenting primary caries or secondary caries next
the dental health of individuals with OI. In Vietnam         to a filling. A missing tooth was a tooth that was
although OI has been assessed medically [14],                extracted due to caries. A filled tooth was a tooth
to the authors’ knowledge, the dental aspects                with restoration but without additional caries. The
of OI types have not been reported. Therefore,               dmft/DMFT score was the sum of decayed, missing
the aim of the current study is to investigate the           and filled teeth.
dental characteristics of persons with OI, including
dentinogenesis imperfecta, dental wear, dental               2.5. Analysis of occlusion
caries experience, and malocclusion.                         Occlusal variables of OI dentition consisted of 10
                                                             variables including overbite, overjet, open bite,
2. MATERIALS AND METHODS                                     posterior crossbite, contact point displacement,
                                                             midline diastema, molar Angle classification, incisal
2.1. Study sample                                            segment crowding, and incisal segment spacing.
This is a cross-sectional study and the total sample
consisted of 74 OI persons aged 2–37 years (mean             2.6. Calibration procedure
age = 10.6 ± 7.1, median age = 9.0) from 34 healthcare       The dental status of an OI person was examined twice
centers across Vietnam. The OI diagnosis was based           on the same day by the first author (MSN) at local
on Sillence’s classification [5] and was confirmed by        healthcare centers to ensuring reliability between
two orthopedic experts. OI participants or their legal       the interval examination and inter-examiner.
representatives signed informed consent forms.               The Kappa value of 0.92 and 0.87 indicated high
The Danang University of Medical Technology and              reliability of the clinical examination. The first author
Pharmacy (No. 523/CN-DHKTYDDN) approved this                 also conducted an analysis of occlusion and dental
study. All procedures were performed according               wear on dental casts. The calculated Kappa values
to the World Medical Association Declaration of              were above 0.85, indicating a high degree of intra-
Helsinki.                                                    examiner and inter-analysis reliability.

2.2. Examination of dentinogenesis imperfecta                2.7. Statistical analysis
DGI was clinically diagnosed according to the Shields'       Data entry and analyses were performed with the
classification [13]. The clinical examination of DGI         Statistical Package for the Social Sciences software



Stoma Edu J. 2020;7(2): 94-101                                              pISSN 2360-2406; eISSN 2502-0285                95
                    Nguyen MS, et al.
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Original Articles       Table 1. Prevalence of dentinogenesis imperfecta and tooth discoloration in persons with osteogenesis imperfecta.


                                                                                                                OI classification
                                                                              Total
                                          Variable                                                                                                  p-valuea
                                                                             N = 74             Type I              Type III         Type IV

                                                                                                n = 25               n = 24          n = 25
                        Dentinogenesis imperfecta
                                                                    No        37.8                60.0                25.0            28.0
                                                                                                                                                     0.019*
                                                                   Yes        62.2                40.0                75.0            72.0
                        Tooth coloration
                        Lightness level

                                                                   0-2        12.2                28.0                 0               8.0
                                                                                                                                                    0.008*b
                                                                   3-5        87.8                72.0                100             92.0
                        Saturation (Chroma)
                                                                  Low         75.7                72.0                79.2            76.0
                                                                 High         24.3                28.0                20.8            24.0           0.842

                        Hue
                                                          Yellowish (L)       10.8                4.0                 8.3             20.0
                                            Intermediate hue (M)              79.7                88.0                79.2            72.0           0.418
                                                           Reddish (R)         9.5                8.0                 12.5             8.0
                    a
                      Chi-square test; b: Fisher's test
                    *
                     Significant.


                        Table 2. Prevalence of dental wear in persons with osteogenesis imperfecta.

                                                                                                                 OI classification
                                                                               Total
                                        Dental wear                                               Type I               Type III       Type IV        p-value
                                                                              N = 74
                                                                                                  n = 25               n = 24          n = 25
                         Prevalence of OI persons with dental wear
                                                        No/mild                        63.5              55.6                 69.6           63.6    0.652a

                                                   Moderate/severe                     36.5              44.4                 30.4           36.4

                     Mean percentage of teeth showing wear in dentition
                                                  No/mild              90.4                              89.7                 93.5           87.9    0.647b
                    version 17.0 (SPSS Inc., Chicago, Illinois, USA). 9.6
                                         Moderate/severe                                        type IV (72%) than type
                                                                                                      10.3          6.5 I (40%, p=0.019).
                                                                                                                                 12.1     Regarding
                    Chi-square test; bANOVA test.
                    a




                    version 17.0 (SPSS Inc., Chicago, IL, USA).                                 color variation, 72% dentition of type I, 92% of type
                    The Chi-square test and ANOVA test were used to                             IV, and 100% of type III were graded in darkness
                    identify the differences related to DGI, dental wear,                       levels. Prevalence of high saturation was fairly
                    occlusal features, and dmft/DMFT score among OI                             equivalent among type I (28.0%), type III (20.8%),
                    types I, III, and IV. An interval confidence level of 95%                   and type IV (24.0%, p=0.842). The hue component of
                    and a two-sided p-value of .05 were set for significant                     the total dentitions was 10.8% of yellowish, 79.7% of
                    difference.                                                                 intermediate hue, and 9.5% of reddish.
                                                                                                There were no differences in hue components among
                    3. RESULTS                                                                  OI types (p = 0.418) (Table 1). Dental wear occurred
                                                                                                in 36.5% of OI individuals, of which 44.4% presented
                    The study included 74 persons with OI aged 2–37                             in type I, 30.4% in type III, and 36.4% in type IV. The
                    years (50% females and 50% males). The distribution                         mean percentage of the amount of tooth wear in
                    of clinical diagnoses was 33.8% type I (n=25), 32.4%                        dentition was found in 12.1% of type IV, 10.5% of
                    type III (n=24), and 33.8% type IV (n=25). Primary                          type I, and 6.5% of type III. However, there were no
                    dentition was accounted for in 31.1% of the sample,                         differences in the distribution of tooth wear among
                    mixed dentition was in 37.8%, and permanent den-                            three types of OI (p>0.05, Table 2). Table 3 shows
                    tition was 31.1%. Dentinogenesis imperfecta was                             the characteristics of dentition associated with each
                    found in 62.2% of the total sample. Prevalence of DGI                       type of OI. According to Angle's classification, class
                    was statistically more frequent in type III (75%) and                       III was more prevalent in type III (66.7%) and type




     96             Stoma Edu J. 2020;7(2): 94-101                                                                   pISSN 2360-2406; eISSN 2502-0285
Osteogenesis imperfecta in Vietnam
                                                                                                                                  www.stomaeduj.com




                                                                                                                                  Original Articles
 Table 3. Prevalence of occlusal features in persons with osteogenesis imperfecta.

                                                                                     OI classification
                                                  Total
                 Variable                                           Type I              Type III         Type IV       p-value
                                                 N = 74
                                                                    n = 25               n = 24          n = 25
 Angle’s classification
                                  Class I                 27.1           43.8                  23.8           18.2       0.231
                                 Class II                 18.6           18.8                      9.5        27.3
                                 Class III                54.2           37.5                  66.7           54.5
 Overbite >3.5mm
                                      No                  80.7           64.3                  90.5           81.8       0.155
                                      Yes                 19.3           35.7                      9.5        18.2
 Increased overjet > 3.5 mm
                                      No                  100             100                     100          100         -
                                      Yes                   0                0                      0              0
 Reverse overjet
                                      No                  39.7            60.0                    33.3         31.8
                                                                                                                         0.173
                                      Yes                 60.3            40.0                    66.7         62.8
 Posterior crossbite
                                      No                  67.8            75.0                    57.1         72.7
                                                                                                                         0.424
                                      Yes                 32.2            25.0                    42.9         27.3
 Open bite
                                      No                  82.5             100                    75.0         77.3
                                                                                                                         0.133
                                      Yes                 17.5               0                    25.0         22.7
 Diastema
                                      No                  86.4            87.5                    90.5         81.8      0.702
                                      Yes                 13.6            12.5                     9.5         18.2
 Displacement > 2mm
                                      No                  66.1            75.0                    52.4         72.7      0.251
                                      Yes                 33.9            25.0                    47.6         27.3
 Incisal segment crowding
                                      No                  53.4            75.0                    42.9         47.6      0.121
                                      Yes                 46.7            25.0                    57.1         52.4
 Incisal segment spacing
                                      No                  66.1            62.5                    76.2         59.1      0.466
                                      Yes                 33.9            37.5                    23.8         40.9

 Missing teeth
                                      No                  76.7            76.5                    76.2         77.3      0.996
                                      Yes                 23.3            23.5                    23.8         22.7
Chi-square test; *Significant.



IV (54.5%) than in type I (37.5%). No OI persons                          DMFT score was 3.0 ± 4.1 and 2.2 ± 4.6 respectively.
had an increased overjet (>3.5mm), but 60.3% of                           The dmft and DMFT scores were equivalent among
individuals had reverse overjet. Posterior crossbite                      types of OI (p>0.05). None of the persons with OI
occurred in 32.2% of the total OI sample, of which                        received restorative treatment for decayed teeth,
42.9% presented in type III, 27.3% in type IV, and                        and none of the permanent teeth in type III and IV
25.0% in type I. High prevalence of incisal segment                       were extracted due to caries.
crowding (46.7%), incisal segment spacing (33.9%),
displacement of tooth>2mm (33.9%), missing teeth                          4. DISCUSSION
(23.3%), open bite (19.3%) and diastema (13.6%)
were also found in the total sample, but no significant                   4.1. General information about Vietnamese persons
differences were observed among type I, III and IV                        with OI. This is a preliminary study conducted in
(p>0.05). Table 4 indicates dental caries experience                      Vietnam to collect the dental characteristics of
within the OI sample; the mean of the dmft and                            persons who suffer from OI. The total sample of our


Stoma Edu J. 2020;7(2): 94-101                                                                 pISSN 2360-2406; eISSN 2502-0285     97
                    Nguyen MS, et al.
www.stomaeduj.com

Original Articles    Table 4. Mean score of dental caries components of primary and permanent teeth in osteogenesis imperfecta patients.

                                                                                                        OI classification
                                                                  Total
                         Dental caries experience                                        Type I             Type III         Type IV          p-value
                                                                 N = 74
                                                                                         n = 25              n = 24           n = 25
                     Primary teeth
                                              dt                   1.8 ± 3.2              0.9 ± 2.0           3.2 ± 4.3        1.7 ± 3.1           0.111
                                             mt                    1.3 ± 2.4              1.1 ± 2.8           1.6 ± 2.3        1.2 ±2.0            0.771
                                               ft                          0                      0                    0               0                -
                                           dmft                    3.0 ± 4.1              1.9 ± 3.4           4.9 ± 4.4        2.8 ± 4.4           0.119
                      Permanent teeth
                                             DT                    1.7 ± 2.4              1.0 ± 1.6            2.3 ±2.9        1.6 ± 2.3           0.295
                                             MT                    0.3 ± 1.8              0.9 ± 3.5                    0               0           0.272
                                              FT                           0                      0                    0               0                -
                                          DMFT                     2.2 ± 4.6              2.9 ±7 .9           2.3 ± 2.8        1.6 ± 2.3           0.753
                    ANOVA test
                    dt/DT: decayed teeth; mt/MT = missing teeth; ft/FT = filled teeth.



                    study was 74 OI persons from thirty-four provinces                            red intermediate to reddish color. Our study found
                    that are home to approximately 60 million of the                              that 36.5% of OI persons had dental wear. This is
                    total population of Vietnam, meaning that the                                 in line with previous investigations that found the
                    prevalence of OI in Vietnam is estimated at 1/480,000.                        prevalence of dental wear ranging from 37.5% to
                    Our prevalence might be lower compared to the                                 66.5% in OI samples [11,12]. Dental wear occurring
                    prevalence of 1/25,000-1/10,000 reported in other                             in OI person could be from DGI. Among DGI types
                    countries [3-5]. Our study lacked information about                           of Shields’ classification, DGI type I is associated with
                    OI in the newborn infant group, and OI’s mild type                            OI because of the inherited disorders of collagen
                    might be undiagnosed in the general population; in                            metabolism; whereas, DGI type II and III are mutations
                    addition, OI type II was excluded from the present                            affecting the dentin sialophosphoprotein gene
                    study. Nonetheless, the distribution of OI types in                           [13]. The mutations in COL1A1 and COL1A2 genes
                    our study approached a range distribution of 39-                              would cause DGI type I that teeth easily expose the
                    79% for type I, 9-24% for type III, and 13-40% for                            abnormal dentine and were typically worn.
                    type IV, as reported in previous studies [10,11,16,17].                       Approximately 10% of teeth in both dentitions
                    Bisphosphonate therapy has good results in                                    were showed a severely worn condition in the
                    increasing the bone mineral density; however, most                            current study. Preventive and restorative care of DGI
                    of our participants could not follow bisphosphonate                           and dental wear are important for Vietnamese OI
                    therapy due to inaccessibility of adequate medical                            persons. The treatment considerations are preser-
                    care, sustainment or counseling from the medical                              vation of occlusal height, maintenance of oral
                    professionals.                                                                function and esthetic needs. Nonetheless, most
                                                                                                  of OI persons might not receive dental treatment
                    4.2. Dentinogenesis imperfecta and dental wear                                because of the family economic hardship; thus, there
                    A high prevalence of DGI was found in Vietnamese                              is a need for more effective support for OI persons to
                    with OI. Our results were in accordance with a study                          approach treatment to restore the harmony of the
                    by Majorana et al. [12] that indicated that 62.5% of                          oral functions.
                    an Italian OI sample had DGI. Conversely, Malgrem
                    [11] and Saeves [10] found that the prevalence of                             4.3. Occlusal features
                    DGI in OI samples in Sweden and Norway was 41.5%                              OI mutation not only has an impact on dental
                    and 19.0%, respectively. Concerning DGI related to                            structure but also on dental occlusion. The findings
                    types of OI, our study is consistent with previous                            of our study indicate that class III malocclusion
                    studies in showing DGI to be more prevalent in                                presented in 54.2% of the sample, which was similar
                    OI type III than in type I and IV [10,18], indicating                         to 60-80% of class III malocclusion in investigations
                    that DGI is related to the severity of OI. DGI is a                           in Taiwan and Canada [7,9]. In the current study,
                    disorder of dentin formation causing deposition                               class III malocclusion was more prevalent in OI
                    of dentine, obliteration of the pulp chamber and                              type III compared to type IV and I. An individual
                    intrinsic discoloration. This could explain the finding                       with OI type III is described as having a triangular
                    that up to 80% of dentition in our OI sample were                             face, and this feature might be associated with
                    graded as having a dark lightness level and yellow-                           class III malocclusion. High prevalence of class III in



     98             Stoma Edu J. 2020;7(2): 94-101                                                                 pISSN 2360-2406; eISSN 2502-0285
Osteogenesis imperfecta in Vietnam
                                                                                                                                    www.stomaeduj.com



the Vietnamese OI sample corresponded with the                4.4. Dental caries experience




                                                                                                                                  Original Articles
prevalence of OI persons having reverse overjet.              Dental caries is a major concern for persons with
Reverse overjet is a manifestation of disharmony              OI because of difficulties with physical activity for
between the maxilla and the mandible. In the current          oral hygiene. The mean score dmft/DMFT of
study, OI persons were likely to have deficient growth        3.0/2.2 indicated a moderate level of dental caries
of the maxilla. The evidence was that a posterior             experience in OI sample. Our findings were in accor-
crossbite presented in 25.0-42.9% of OI types,                dance with previous studies that highlighted oral
with no OI persons having an overjet > 3.5mm, a               problems among the OI population. Saeves et al.
parameter indicating a protrusive maxilla. Our study          [10] described that although OI patients in Norway
was strongly supported by previous studies. Chang             had regular dental visits and daily oral health habits,
et al. [7] reported a shorter upper facial length in an       their oral status was not as good as compared to the
OI sample as compared to a healthy sample. By using           general population. Differently from the findings
the discrepancy index in orthodontic treatment,               of Saeves in Norway, none of the Vietnamese
Rizkalla et al. [9] found OI to be related with anterior      individuals with OI received any restorative treat-
and posterior crossbite. Scalia et al. [19] concluded         ment for decayed teeth. The physical disability of
that malocclusion of OI was associated with a                 persons with OI might influence their ability to visit
retrognathic maxilla. The impairment of maxilla               a dentist for dental treatment; in addition, most
growth could be from a lack of type I collagen due            of them were from healthcare centers that only
to mutation. In addition, the symptom of loose                focused on rehabilitation of OI patients. The dental
joints could be observed in severe cases of OI. When          issues and lack of dental visits could accelerate caries
occurring in the temporomandibular joint, it can              development in OI persons; however, the num-
stretch more than normal and lead to abnormal jaw             ber of decayed teeth of Vietnamese people with
relations. The deficiency of maxillary length might           OI was lower compared to the general population
also lead to teeth crowding. Our study found that             in Vietnam [22]. This is possibly related to DGI
both the prevalence of displacement of tooth > 2mm            presenting in persons with OI. In DGI dentition,
and incisal segment crowding gradually increased              the presence of obliterated dentinal tubules and
from OI type I to type IV and type III. According to          pulp chamber can prevent penetration of harmful
Sillence’s classification for living OI patients, type I is   bacteria, although enamel has chipped away. This
the mildest form, whereas type III is the most severe         might explain that the missing teeth component in
form. Such severe deformities of OI type III and IV           our study (mt/MT=1.3/0.3) resulted from hypodontia
influenced the defective growth of the maxilla and            as aforementioned, not by the impact of caries. The
might also be associated with disharmony of growth            shortcoming of our study is an absence the control
between the two jaws.                                         group to compare with the OI sample in evaluation
The evidence was that over 20% of people with OI              the risk of oral problems. In addition, radiographic
type III and IV had an open bite in contrast with 0%          examination was not carried out for OI participants
of type I. Waltimo-Siren et al. [17] indicated that           to determine the reasons for missing teeth due to
the gonial angle of OI type I was 124.6 degrees,              impacted teeth or hypodontia.
which was lower compared to the 126.3 degrees
of OI type III/IV. Similarly, Chang et al. [7] found a        5. CONCLUSION
clockwise rotation of the mandible of OI patients as
compared to the control group. Such alterations in            There was a high prevalence of dentinogenesis imper-
the mandible might be associated with an open-bite            fecta and dental wear in the Vietnamese OI sample,
of occlusion in OI patients.                                  especially in OI type III and IV. The occlusal features of
The mutations of COL1A1 and COL1A2 in persons                 OI persons were determined with a high prevalence
with OI might prohibit tooth formation and                    of class III, malocclusion, overjet, open bite, posterior
development. In the current study, the prevalence             crossbite, and missing teeth. The dental caries
of missing teeth was equivalent among OI types,               experience of persons with OI was at a moderate
and it ranged from 22.7-23.8%; that was much                  level, and none of the study’s subjects had received
higher compared to 0.5-11.0% of missing teeth in              any dental restorations.
the general population [20]. The findings related to
missing teeth in our study are reinforced by previous         CONFLICT OF INTEREST
OI studies. Tooth agenesis was found in 17% of                The authors declare no conflict of interest.
the OI sample, including 11% hypodontia and 6%
oligodontia [18].                                             AUTHOR CONTRIBUTIONS
Approximately 14% of individuals with OI type III
                                                              MSN: performed clinical studies, data acquisition, statistical
had congenital missing teeth [21], and in our study,          analysis, and manuscripts writing, MS: analysis results,
missing teeth accounted for 23.8% of OI type III. The         proofreading, BH: data acquisition, KM: data acquisition and
odds of having missing teeth among persons with               interpretation of the results, SK: interpretation of the results,
OI was more 2.0-4.7 times compared to the general             AM: data acquisition, TT: data acquisition and manuscript
population [8,10].                                            literature search, TJ: protocol, proofreading.




Stoma Edu J. 2020;7(2): 94-101                                                   pISSN 2360-2406; eISSN 2502-0285                    99
                    Nguyen MS, et al.
www.stomaeduj.com

Original Articles   ACKNOWLEDGMENTS


                    This study was supported by the Estonian Science Foundation
                    grant ESF 9255, the Estonian Research Council IUT 20-46 and
                    Eramus+ EDUSHARE projects.



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  100               Stoma Edu J. 2020;7(2): 94-101                                                             pISSN 2360-2406; eISSN 2502-0285
Osteogenesis imperfecta in Vietnam
                                                                                                                                 www.stomaeduj.com




                                                                                                                                 Original Articles
                                                                               Minh Son NGUYEN
                                                                                      DDS, PhD, Head
                                                                       Faculty of Odonto-Stomatology
                                                 Danang University of Medial Technology and Pharmacy
                                                                                  Danang City, Vietnam



CV
Minh Son Nguyen was awarded a PhD degree in 2018 at the Institute of Dentistry, University of Tartu. Currently, he is the Head
of the Faculty of Odonto-Stomatology and a lecturer at the Danang University of Medical Technology and Pharmacy, Vietnam.
Dr. Nguyen has published peer-reviewed articles related to temporomandibular disorders, prosthodontics, and community
dental health.




Questions
1. Osteogenesis imperfecta is a genetic mutation affecting
qa. Connective tissue;
qb. Bone;
qc. Eyes;
qd. Dentition.

2. Which type of osteogenesis imperfecta cannot be observed in living persons?
qa. Type I;
qb. Type II;
qc. Type III;
qd. Type IV.

3. The high prevalence of malocclusion that can be observed in persons with OI is related to
qa. Angle’s class I;
qb. Angle’s class II, division I;
qc. Angle’s class II, division II;
qd. Angle’s class III.

4. Which type of dentinogenesis imperfecta is associated with osteogenesis imperfecta?
qa. Only DGI type I;
qb. DGI type I and type II;
qc. DGI type I and type III;
qd. DGI type II and type III.




Stoma Edu J. 2020;7(2): 94-101                                                   pISSN 2360-2406; eISSN 2502-0285                101