conservative orthodontic treatment for skeletal open bite associated with amelogenesis imperfecta

JDC CASE REPORT

96 Bechor et al Journal of Dentistry for Children-812 2014Open bite with Amelogenesis Imperfecta

ABSTRACTAmelogenesis imperfect (AI) is a hereditary dental condition that affects tooth enamel resulting in small and discolored teeth tooth sensitivity poor esthetics and anterior open bite associated with severe discrepancy in the vertical relation of the jaws Treat-ment can be complex and includes an interdisciplinary approach involving orthodontics oral surgery and restorative therapy The purpose of this report is to describe the case of a 12-year-old girl with AI and severe open bite who received conservative non-surgical therapy that led to good functional occlusion and acceptable dental and facial esthetics A three-year follow-up showed excellent post-treatment stability (J Dent Child 201481(2)96-102) Received December 28 2012 Last Revision February 24 2013 Revision Accepted February 27 2013

Keywords open bite amelogenesis imperfecta orthodontic treatment

Drs 1Bechor and 2Finkelstein are instructors 3Dr Shapira is a clinical associate professor and 4Dr Shpack is a lecturer all in the Depart- ment of Orthodontics The Maurice and Gabriela Goldschleger School of Dental Medicine Tel Aviv University Tel Aviv IsraelCorrespond with Dr Shapira at yehoshuashapiragmailcom

Open bite is defined as an inherited developmental or acquired malocclusion whereby no vertical overlap exists between the maxillary

and mandibular anterior teeth (anterior open bite) or no vertical contacts are exhibited between the maxillary and mandibular posterior teeth (posterior open bite)1 An open bite may be localized and thus may involve only a few teeth due to a digit-sucking habit or other local factors (dental open bite) or it may be caused by diver- gence of the skeletal planes (skeletal open bite)1

Supra-eruption of the maxillary posterior teeth typi-cally accompanies a skeletal open bite pattern resulting in a downward and backward rotation of the mandible The treatment of skeletal open bite is extremely difficult

Conservative Orthodontic Treatment for Skeletal Open Bite Associated with Amelogenesis Imperfecta

Naomi Bechor DMD1 Tamar Finkelstein DMD2

Yehoshua Shapira DMD3 Nir Shpack DMD MCs4

and should be directed primarily to the elimination of the causative factor by depression (intrusion) of maxillary molars and not elongation (extrusion) of incisors2-4

Amelogenesis imperfecta (AI) is a group of hereditary developmental dental disorders primarily affecting the enamel formation of both the primary and permanent dentitions AI is associated with other dental anomalies such as delayed tooth eruption congenitally missing teeth dentin dysplasias pulp calcification hypercemen- tosis crown malformation root resorption taurodontism small and discolored teeth increased lower anterior facial height and pronounced open bite5

The anterior open bite frequently found in AI patients has always been associated with a severe discrepancy in the vertical relationship of the jaws and supra-eruption of the posterior teeth2 It has been suggested that the open bite is caused by a genetically determined anomaly of craniofacial development instead of local factors influencing alveolar growth2 AI appears to be mainly an inherited autosomal dominant trait but may also occur as autosomal recessive or linked to chromosome X6

Bechor et al 97Open bite with Amelogenesis Imperfecta Journal of Dentistry for Children-812 2014

Two genes associated with AI are the amelogenin and enamelin genes

Several classification systems for AI have been suggested and are based on clinical features and mode of inheritance The most widely accepted one was proposed by Witkop and Rao7 who distinguished three broad categories based on phenotype (clinical appearance) and mode of inheritance

1 Hypoplastic type characterized by deficient enamel with reduced thickness but relatively normal calcification These teeth may have small crowns with white or yellow-brown color

2 Hypocalcified type characterized by fully formed enamel with normal thickness but poor calcification

3 Hypomaturation type characterized by enamel that has normal thickness but poor mineraliza- tion as well as mottled enamel that often abrades and chips easily

Other suggested classifications are subcategories of the three broad AI types each with multiple subtypes8

The reported prevalence of AI is 60 percent to 70 percent for the hypoplastic type 20 percent to 40 percent for the hypomaturation type and seven percent for the hypocalcification type9 The degree of diversity of the condition depends on the clinical manifestations and the pattern of inheritance9

The prevalence of AI widely varies between 14000 in Sweden10 to 114000 in the US11 The prevalence of anterior open bite in AI patients varies from 24 percent to 60 percent which is much higher than the three percent to seven percent found in the general popula- tion312 Skeletal open bite can be observed in all three major types of AI4 The severity of enamel phenotype did not necessarily correspond with the presence or severity of open bite malocclusion4

Treatment of AI during childhood involves using stainless steel crowns (SSCs) on posterior teeth which may be replaced by porcelain crowns in adulthood and composite restorations on anterior teeth13 Several reports have described the clinical procedures of es- thetic and functional rehabilitation of AI patients Management can range from early preventive procedures to complete restorative treatment depending on the severity of the case1415 For non-growing individuals a multidisciplinary treatment approach has been recommended including orthodontics perio- dontics oral surgery and restorative rehabilitation with full-coverage metal-ceramic crowns1617

The main clinical problems associated with AI are poor esthetics anterior open bite tooth discoloration extensive loss of tooth material and thermal sensiti- vity718 The purpose of this report is to describe the case of a 12-year-old girl with AI and severe open bite who received conservative therapy that led to good functional occlusion and acceptable dental and facial esthetics

CASE REPORTA 12-year-old girl with hypoplastic AI was referred for orthodontic treatment Her family history was remark- able for a brother who presented with the same condition Her medical health history was non-contributory but she suffered from low self-esteem because of the poor appearance of her teeth and her inability to chew pro- perly She had a dolichocephalic symmetric face with long lower anterior facial height Her profile was convex retrognathic with incompetent lips She had a skeletal Class II Division I malocclusion with an overjet of four mm and an open bite of six mm extending from the permanent right first molar to the left first molar bilateral crossbite due to a constricted maxillary arch spaced dentition due to enamel deficiency active tongue- thrusting habit at rest while swallowing and during speech and thumb-sucking at night Her dentition was caries free and she had good oral hygiene The permanent maxillary and mandibular first molars were covered with ion SSCs and the incisal edges of the maxillary and mandibular incisor crowns were broken The permanent maxillary central incisors were covered with composite restorations The teeth were small and yellow-brown in color (Figures 1 and 2)

A cephalometric radiograph (Figure 3) analysis re- vealed a hyperdivergent clockwise rotation of the mandible with a mandibular plane angle (Frankfort Mandi- bular Angle) of 36 degrees and an increased lower anterior facial height (Anterior Nasal Spine to Menton) of 78 mm (Table)

Table Cephalometric Measurements Before and After Treatment (Degrees)

Cephalometric measurements

Normal Pre- treatment

Post- treatment

Difference

SNA 82 75 75 0

SNB 80 70 74 4

ANB 2 5 1 -4

Go-Gn to SN 32 40 36 -4

FMA 25 36 34 -2

IMPA 90 80 76 -4

ANS-Me (mm) 62 78 73 -5

UI tip to PP (mm) 27 26 26 0

U6 cusp to PP (mm) 23 25 20 -5

LI tip to MP (mm) 40 30 31 1

L6 cusp to MP (mm) 32 26 26 0

UI=upper incisor LI=lower incisor U6=upper first molar L6=lower first molar PP=palatal plane MP=mandibular plane SNA=Angle between Sella Nasion to A Point SNB=Angle between Sella Nasion to B Point ANB=Angle between A point Nasion and B Point Go-Gn to SN=Angle between Gonion- Gnathion to Sella-Nasion FMA=Frankfort Mandibular Angle IMPA=Incisor to Mandibular Plane Angle ANS-Me=Anterior Nasal Spine to Menton

Open bite with Amelogenesis Imperfecta Journal of Dentistry for Children-812 201498 Bechor et al

TREATMENT OBJECTIVES The purpose of treatment was to prevent further tongue-thrusting and thumb-sucking habits eliminate the bi-

lateral crossbite close the severe open bite achieve a Class I canine and molar relationship establish normal functional occlusion and improve dental and facial esthetics

TREATMENT ALTERNATIVESOrthognathic surgery was the first treatment alternative offered for pos-terior maxillary impaction to reduce the posterior vertical dimension al-lowing counter-clockwise rotation and forward positioning of the man-dible The patient was too young for surgery however and treatment would have to be postponed until the end of her growth and development The patientrsquos desire was to improve her dental function and facial esthetics at the earliest possible opportunity and not wait so long The patient also de- clined a second option for intrusion of the posterior teeth using mini-screws or mini-implants Therefore the non-surgical conservative orthodontics al-ternative which would eliminate the tongue-thrusting and thumb-sucking habits and close the open bite by molar intrusion was accepted by the patient and her parents with the clear under- standing of the need for good com- pliance and the possibility of future relapse Informed consent was signed for treatment

TREATMENT PROGRESSVertical control was directed to prevent an increase in posterior alveolar height by intrusion of the molars This was achieved by using a mandibular Hawley type appliance with posterior bite blocks and an expanded quad-helix with a tongue crib to correct the bilateral crossbite and her habits (Fig-ure 4) As the open bite reduced she started with exercises to improve her

Figure 1 Pre-treatment facial and intraoral photographs

Figure 2 Pre-treatment dental casts


speech and train her tongue At the next phase of treatment a 0022-inch pre-adjusted fixed appliance combined with high-pull head gear was used for leveling and aligning both dental arches Class II elastics were used to correct the Class II molar relationship and vertical elastics for incisor extrusion were used in the final stage to close up the bite

TREATMENT RESULTSUsing conservative orthodontic therapy with good co- operation resulted in closing the severe open bite A Class I molar and canine occlusion with normal overbite and overjet were attained and the transverse discrepancy was resolved A significant improvement in dental and facial esthetics was achieved (Figures 5 6 and 7) Composite restorations were done to correct the occlusal and inter- proximal contacts and improve esthetics (Figure 6) To-tal active treatment time was 27 months after which the patient was given maxillary and mandibular bonded canine-to-canine fixed retainers and maxillary removable Hawley and mandibular Omnivac type retainers

DISCUSSIONOur patient presented one of the autosomal recessive forms of hypoplastic AI She had anomalies both in the size and shape of her teeth and a yellow-brown enamel coloration Her posterior dentoalveolar heights were in-creased resulting in long lower facial height and skeletal open bite with a tongue-thrusting habit AI patients have a significantly higher prevalence of open bite than the general population Reports in the orthodontic literature emphasize the association between AI and open bite249 Rowley et al2 proposed that the association between the high prevalence of anterior open bite and AI was due more to a genetic abnormality of craniofacial development

Figure 3 Pre-treatment panoramic and cepha-lometric radiographs

Figure 4 Mandibular bite block and quad-helix with tongue crib

Figure 5 Post-treatment facial photographs


with severe discrepancy in the vertical relation of the jaws and less to local factors influencing alveolar growth Witkop et al718 on the other hand suggested that the frequent association between anterior open bite and AI is attributed to rough and thermally sensitive teeth that may lead to a tongue-thrusting habit that produces an anterior open bite by impeding alveolar growth

It is well known that orthodontic treatment of skeletal anterior open bite is extremely difficult and a challenge for the orthodontist Inhibition of vertical development of the posterior segments by intrusion of the molars is indicated in growing individuals with skeletal open bite19 Therefore a lower posterior bite block appliance was used for this patient to intrude the maxillary molars

and reduce the open bite Some have also suggested the use of mini or micro screw implant skeletal anchorage for posterior impaction and open bite correction2021

A combined orthodontic and surgical treatment ap-proach is often required to correct skeletal open bite in non-growing individuals It is agreed that surgery combined with orthodontics is the best manner to correct skeletal open bite as it offers a higher probability of post-treatment stability22 However most patients and their parents do not agree to postpone treatment until the end of growth and development and prefer non- surgical correction of the anomaly by conservative orthodontic therapy remaining aware that this simply camouflages the skeletal disharmony23 The conservative

method described in this case report is simple and often accepted by patients and parents can be used immediately and does not require invasive procedures such as mini-screws implants or orthog-nathic surgery This treatment option should be considered to avoid a possible surgical risk

Cephalometric radiographs and its superimposition (Figures 8 and 9) re- vealed considerable intrusion of the maxillary molars counter-clockwise rotation of the mandible and significant closing of the large open bite Decrease of the Frankfort Mandibular Angle from 36 to 34 degrees and Gonion-Gnathion to Sella-Nasion from 40 to 36 degrees re-duced the anterior lower facial height (Anterior Nasal Spine to Menton) from 78 to 73 mm (Table) The height of maxillary molar cusp tip to the palatal plane (Anterior Nasal Spine to Posterior Nasal Spine) was reduced by five mm The height of the maxillary incisor tip to the palatal plane did not change and no vertical change was found in the position of the maxillary incisor centroid The height of the mandibular incisor tip to the mandibular plane increased by one mm while the vertical position of the mandibular molars to the mandibular Figure 6 Post-treatment intraoral photographs

Figure 7 Post-treatment dental casts


plane did not change These findings indicate a significant intrusion of the maxillary molars reducing posterior vertical height and closing up the open bite

The subject of this report is of major interest to pediatric dentists who are often the first oral health professionals to see young children and thus should be aware of treatment alternatives for skeletal open bite as-sociated with AI This case illustrates how conservative orthodontic mechanics may achieve excellent outcomes and long-term stability without surgical intervention Full-coverage restorations are required to provide max- imum protection and improve esthetics and function Three-year post-treatment photographs show good stability of the orthodontic procedure (Figure 10)

Figure 8 Post-treatment panoramic and cephalometric radiographs

Figure 9 Superimposition of pre- and post-treatment cephalometric tracings

Figure 10 Three-year post-treatment intraoral photographs


A multidisciplinary team that includes an orthodontist pediatric dentist oral surgeon and prosthodon-tist is the key to successfully treat severe open bite in AI patients This case report focused on the conservative non-surgical intervention of a severe skeletal open bite using fixed orthodontic mechanotherapy which successfully improved the patientrsquos dental function and facial esthetics The composite restorations she had can be replaced in the future by porcelain laminate crowns

ACKNOWLEDGMENTThe authors wish to thank Mr Amir Shapira BSc Eng for his valuable assistance in the preparation of this manuscript

REFERENCES1 Daskalogiannakis J Glossary of Orthodontic Terms

Chicago Ill Quintessence Publishing Co 20002 Rowley R Hill FJ Winter GB An investigation

of the association between anterior open bite and amelogenesis imperfecta Am J Orthod 198281 229-35

3 Nahoum HI Horowitz SL Benedicto EA Varieties of anterior open bite Am J Orthod 197261 486-92

4 Ravassipour DB Powell CM Phillips CL et al Va- riation in dental and skeletal open bite malocclusion in humans with amelogenesis imperfecta Arch Oral Biol 200550611-23

5 Collins MA Mauriello SM Tyndall DA Wright JT Dental anomalies associated with amelogenesis imperfecta a radiographic assessment Oral Surg Oral Med Oral Pathol 199988358-64

6 Weinmann JP Svoboda JFWoods RW Hereditary disturbances of enamel formation and calcification J Am Dent Assoc 194532397-418

7 Witkop CJ Rao S Inherited defects in tooth structure Birth Defects 19718153-84

8 Crawford PJM Aldred M Bloch-Zupan A Amelogenesis imperfecta Orphanet J Rare Dis 2007217-28

9 Backman B Lundgren T Engstrom UE et al The absence of correlation between a clinical classification and ultra-structural finding in amelogenesis imperfecta Acta Odontol Scand 19935179-89

10 Sundell S Hereditary amelogenesis imperfecta an epidemiological genetic and clinical study in Swe- dish child population Swed Dent J 198631 (suppl)1-38

11 Witkop CJ Hereditary defects in enamel and dentin Acta Genet Statist Med 19577236-9

12 Proffit WR Fields HW Jr Contemporary Ortho- dontics 2nd ed St Louis Mo CV Mosby Co 2002

13 Bouvier D Duprez JP Bois D Rehabilitation of young patients with amelogenesis imperfecta a report of two cases J Dent Child 199663443-7

14 Rosenblum SH Restorative and orthodontic treat-ment of an adolescent patient with amelogenesis imperfecta Pediatr Dent 199921289-92

15 Sari T Usumez A Restoring function and esthetics in a patient with amelogenesis imperfecta a clinical report J Prosthet Dent 200390522-5

16 Toksavul S Ulusoy M Turkun M Kumbuloglu O Amelogenesis imperfecta the multidisciplinary approach A case report Quintessence Int 2004 3511-4

17 Greenfield R Iacono V Zove S Baer P Periodontal and prosthodontic treatment of amelogenesis imperfecta J Prosthet Dent 199268572-4

18 Witkop CJ Sauk JJ Hereditary enamel defects In Stewart RE Prescott GH eds In Oral Facial Genetics St Louis Mo CV Mosby Co 1976151-226

19 Kucera J Marek I Tycova H Baccetti T Molar height and dentoalveolar compensation in adult subjects with skeletal open bite Angle Orthod 201181564-9

20 Kravitz ND Kusnoto B Posterior impaction with orthodontic mini screw for open bite closure and improvement of facial profile World J Orthod 20078157-66

21 Park HS Kwon TG Kwon OW Treatment of open bite with micro screw implant anchorage Am J Orthod Dentofac Orthop 2004126627-36

22 Denison TF Kokich VG Shapiro PA Stability of maxillary surgery in open bite versus non-open bite malocclusions Angle Orthod 1989595-10

23 Sugawara J Aymach Z Nagasaka H Kawamura H Nanda R Non-surgical correction of skeletal open bite a goal-oriented approach evaluated by CBCT J Clin Orthod 201145145-55


Two genes associated with AI are the amelogenin and enamelin genes

Several classification systems for AI have been suggested and are based on clinical features and mode of inheritance The most widely accepted one was proposed by Witkop and Rao7 who distinguished three broad categories based on phenotype (clinical appearance) and mode of inheritance

1 Hypoplastic type characterized by deficient enamel with reduced thickness but relatively normal calcification These teeth may have small crowns with white or yellow-brown color

2 Hypocalcified type characterized by fully formed enamel with normal thickness but poor calcification

3 Hypomaturation type characterized by enamel that has normal thickness but poor mineraliza- tion as well as mottled enamel that often abrades and chips easily

Other suggested classifications are subcategories of the three broad AI types each with multiple subtypes8

The reported prevalence of AI is 60 percent to 70 percent for the hypoplastic type 20 percent to 40 percent for the hypomaturation type and seven percent for the hypocalcification type9 The degree of diversity of the condition depends on the clinical manifestations and the pattern of inheritance9

The prevalence of AI widely varies between 14000 in Sweden10 to 114000 in the US11 The prevalence of anterior open bite in AI patients varies from 24 percent to 60 percent which is much higher than the three percent to seven percent found in the general popula- tion312 Skeletal open bite can be observed in all three major types of AI4 The severity of enamel phenotype did not necessarily correspond with the presence or severity of open bite malocclusion4

Treatment of AI during childhood involves using stainless steel crowns (SSCs) on posterior teeth which may be replaced by porcelain crowns in adulthood and composite restorations on anterior teeth13 Several reports have described the clinical procedures of es- thetic and functional rehabilitation of AI patients Management can range from early preventive procedures to complete restorative treatment depending on the severity of the case1415 For non-growing individuals a multidisciplinary treatment approach has been recommended including orthodontics perio- dontics oral surgery and restorative rehabilitation with full-coverage metal-ceramic crowns1617

The main clinical problems associated with AI are poor esthetics anterior open bite tooth discoloration extensive loss of tooth material and thermal sensiti- vity718 The purpose of this report is to describe the case of a 12-year-old girl with AI and severe open bite who received conservative therapy that led to good functional occlusion and acceptable dental and facial esthetics

CASE REPORTA 12-year-old girl with hypoplastic AI was referred for orthodontic treatment Her family history was remark- able for a brother who presented with the same condition Her medical health history was non-contributory but she suffered from low self-esteem because of the poor appearance of her teeth and her inability to chew pro- perly She had a dolichocephalic symmetric face with long lower anterior facial height Her profile was convex retrognathic with incompetent lips She had a skeletal Class II Division I malocclusion with an overjet of four mm and an open bite of six mm extending from the permanent right first molar to the left first molar bilateral crossbite due to a constricted maxillary arch spaced dentition due to enamel deficiency active tongue- thrusting habit at rest while swallowing and during speech and thumb-sucking at night Her dentition was caries free and she had good oral hygiene The permanent maxillary and mandibular first molars were covered with ion SSCs and the incisal edges of the maxillary and mandibular incisor crowns were broken The permanent maxillary central incisors were covered with composite restorations The teeth were small and yellow-brown in color (Figures 1 and 2)

A cephalometric radiograph (Figure 3) analysis re- vealed a hyperdivergent clockwise rotation of the mandible with a mandibular plane angle (Frankfort Mandi- bular Angle) of 36 degrees and an increased lower anterior facial height (Anterior Nasal Spine to Menton) of 78 mm (Table)

Table Cephalometric Measurements Before and After Treatment (Degrees)

Cephalometric measurements

Normal Pre- treatment

Post- treatment

Difference

SNA 82 75 75 0

SNB 80 70 74 4

ANB 2 5 1 -4

Go-Gn to SN 32 40 36 -4

FMA 25 36 34 -2

IMPA 90 80 76 -4

ANS-Me (mm) 62 78 73 -5

UI tip to PP (mm) 27 26 26 0

U6 cusp to PP (mm) 23 25 20 -5

LI tip to MP (mm) 40 30 31 1

L6 cusp to MP (mm) 32 26 26 0

UI=upper incisor LI=lower incisor U6=upper first molar L6=lower first molar PP=palatal plane MP=mandibular plane SNA=Angle between Sella Nasion to A Point SNB=Angle between Sella Nasion to B Point ANB=Angle between A point Nasion and B Point Go-Gn to SN=Angle between Gonion- Gnathion to Sella-Nasion FMA=Frankfort Mandibular Angle IMPA=Incisor to Mandibular Plane Angle ANS-Me=Anterior Nasal Spine to Menton
























































conservative orthodontic treatment for skeletal open bite associated with amelogenesis imperfecta

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