Craniofacial and dental dysmorphology in patients with median facial dysplasia: long-term follow-up

Abstract

Median facial dysplasia affects a subset of patients with cleft lip and palate exhibiting certain characteristics of median facial structure deficiencies without definable gross abnormalities of the brain. The aim of this study was to describe the craniofacial and dental morphology of almost skeletally mature patients with median facial dysplasia. Patients were selected for this retrospective study if they were diagnosed with median facial dysplasia and ≥15 years old. The craniofacial and dental morphology was evaluated by analysing cephalometric and panoramic radiographs. This sample of median facial dysplasia patients (9 males and 11 females; 6 unilateral and 14 bilateral clefts) had a mean age of 16.7 ± 1.9 years. Controls were age-, sex-, cleft type-matched, and nonsyndromic patients. The results showed that in patients with median facial dysplasia, the anterior cranial base and midface were shorter than in controls. The median facial dysplasia inter-orbital distance was shorter and the nasal bone was more retrusive than in controls. All patients with median facial dysplasia had several missing permanent teeth. These features require extensive surgical, orthodontic, and dental rehabilitation procedures.

Median facial dysplasia is found in a subset of patients with cleft lip and palate. Although rare, median facial dysplasia is seen in patients treated in cleft/craniofacial centres; it has an incidence of 2% . Its clinical presenting features were defined in 1982 by N oordhoff & C heng , and clinical presentations were subsequently reported .

The clinical features of median facial dysplasia result in a characteristic appearance that is difficult to correct. Patients have midline facial deficiencies typified by nasolabiomaxillary hypoplasia: poorly developed septum, small alar cartilages, deficient columella, ill-defined Cupid’s bow, absent labial frenulum, and hypoplastic premaxilla, giving a concave profile and a Class III malocclusion ( Figs 1 and 2 ) . The clefts are most frequently complete clefts of the lip and palate, but can also be incomplete. As with ordinary nonsyndromic patients, the clefts seen in median facial dysplasia patients vary in severity.

Fig. 1
Median facial dysplasia with bilateral cleft lip and palate. Preoperative findings (a, b). Fifteen years after repair of bilateral cleft lip and soft palate and positioning of alar cartilages, followed by soft palate repair (c, d). Hard palate repair and columellar lengthening at age 6 years.

Fig. 2
Radiographic findings in a patient with median facial dysplasia and unilateral cleft lip and palate. Intraoperative lateral film (at soft palate repair) shows hypoplastic anterior cranial base and maxilla (a). Lateral cephalogram of 4-year-old documents severe antero-posterior jaw discrepancy (b). Panoramic radiograph shows right alveolar cleft and missing right maxillary permanent central incisor, left maxillary permanent lateral incisor, and hypoplastic right maxillary permanent lateral incisor (c).

Other features include absent maxillary incisors on the cleft side in unilateral clefts ( Fig. 2 ) and the presence of a diminutive premaxilla with one incisor in bilateral clefts ( Fig. 3 ). Such abnormalities present a significant treatment burden on young patients with median facial dysplasia, and further surgical intervention is required by the time they reach adolescence to adulthood. The patients’ facial aesthetics and function can be greatly improved by procedures such as maxillary advancement with or without mandibular setback, secondary cheiloplasty and rhinoplasty when delivered by a multidisciplinary team . Surgical manipulation can be technically demanding in patients with median facial dysplasia.

Fig. 3
Presurgical orthodontics to prepare for alveolar bone grafting. Before presurgical orthodontics (a). Before alveolar bone grafting (b). Four months after alveolar bone grafting (c).

The various presentations of patients with median facial dysplasia have been described in detail , but their craniofacial characteristics and dental abnormalities have not been fully addressed. The aim of this study was to perform a cephalometric analysis of the craniofacial skeleton in median facial dysplasia patients who were almost skeletally mature and to compare these patients to an age-, sex-, and cleft type-matched control sample. Anomalies in the patients’ permanent dentition were also investigated.

Methods

For this retrospective study, the authors reviewed the charts of patients ≥15 years old, diagnosed with median facial dysplasia, and treated at their centre from 1978 to 2006. The charts were reviewed for information about: age; sex; dental anomalies; cleft type, timing, sequence and techniques of lip, palate and alveolus repair; velopharyngeal surgery; lip/nose revision; panoramic radiographs; cephalometric radiographs; distraction osteogenesis; and orthognathic surgery. The diagnosis was confirmed by neonatal and postoperative photographs, according to the defined clinical features, and by the medical chart description of an experienced plastic surgeon, orthodontist or clinical geneticist.

Craniofacial morphology was evaluated by cephalometric analysis ( Fig. 4 ). Lateral and postero-anterior cephalometric radiographs were obtained according to the standardized guidelines with a natural head position and the teeth in centric occlusion. Cephalometric analysis was performed from the most recent cephalograms prior to distraction osteogenesis or orthognathic surgery. A single orthodontist (YFL), blinded to the patients’ diagnosis, traced all radiographs, marked landmarks ( Fig. 4 ), and measured cephalometric variables. Intra-examiner reliability was assessed by YFL duplicating tracings, marking landmarks, and measuring 10 randomly selected radiographs at least 1 month apart. The average measurement errors for linear and angular variables, evaluated by method error statistics , were 0.4 mm (range 0.2–0.6) and 0.6° (range 0.2–0.9), respectively.

Fig. 4
Landmarks used in cephalometric analysis. Landmarks and references lines or planes used in a lateral cephalometric radiograph (a). A = A point; ANS = anterior nasal spine; Ar = articulare; B = B point; Ba = basion; Gn = gnathion; Go = gonion; LI = lower incisor; Men = menton; MP = mandibular plane, a line from Men tangent to the posteroinferior border of the mandible; N = nasion; N ’ = tip of nasal bone; PMP = posterior maxillary point; Pog = pogonion; R = registration point, point of crossing of the greater wing of sphenoid and planum sphenoidale; S = sella turcica; SN = sella-nasion line; UI = upper incisor. Landmarks used on a postero-anterior cephalometric radiograph (b). Ecc = external cranial contour (right side); Mo = Medio-orbitale (right side); Lo = latero-orbitale (right side); Lpa = lateral pyriform aperture (right side); Mx = maxillare (right); Ag = antegonion (right side) (The corresponding landmarks on the left side are noted by ′).

Median facial dysplasia patients were assessed for several cephalometric variables: calvarium, cranial base, orbital cavity, nasal bone, maxilla, mandible, and dentition. These data were obtained from cephalometric radiographs in the Chang Gung Craniofacial Centre cleft database and compared with those in age-, sex- and cleft type-matched and nonsyndromic control patients. Age matches were within 6 months and were randomly selected from the cleft database.

The occurrence of dental anomalies was determined by examining dental records and panoramic radiographs during the entire treatment period. All examinations were made by one investigator (YFL). The first panoramic radiograph usually included primary or early mixed dentition. Records including both primary and permanent dentition were available for all patients with median facial dysplasia. The most common dental anomalies were recorded, including tooth agenesis, supernumerary teeth, microdontia, transposition, and impacted teeth.

Differences between data sets for patients with median facial dysplasia and controls were analysed by Wilcoxon signed rank tests. Statistical analyses were carried out using SPSS v 12.0 (Chicago, IL, USA). P values were two-sided and significant if P < 0.05.

Results

A review of 1020 cleft patients’ charts revealed 20 patients (9 males and 11 females) with a confirmed diagnosis of median facial dysplasia, at least 15 years old, and with available radiographs. These patients were all Taiwanese and had a mean age of 16.7 years (range 15–20). Of these 20 patients, 14 had bilateral clefts of the lip and palate (13 complete and 1 incomplete), and 6 had complete unilateral clefts of the lip and palate. All 20 patients had abnormal permanent dentition, with the most frequently observed anomaly being tooth agenesis ( n = 20, 100%) followed by microdontia ( n = 12, 60%), impaction ( n = 3, 15%), and transposition ( n = 2, 10%). Most frequently, patients had missing or dysmorphic maxillary incisors. The frequency of missing central incisors was equivalent to that of missing lateral incisors. Eight patients presented at least one tooth missing outside the cleft area (40%). Oligodontia (absence of six or more permanent teeth) was more frequently observed in bilateral than in unilateral patients (4 of 14, 28% vs. 0 of 6, 0%) ( Table 1 ).

Table 1
Number of teeth most commonly affected by dental anomalies in median facial dysplasia by cleft type.
Maxillary incisors
Central Lateral Maxillary canines Maxillary premolars
Cleft type Agenesis Microdontia Agenesis Microdontia Agenesis Agenesis
Unilateral
Complete 6 0 6 4 0 0
Bilateral
Complete 16 2 16 8 6 13
Incomplete 1 0 2 0 0 0
Total 23 2 24 12 6 13

All patients had their cleft lip and palate repaired using similar techniques. Wide lip clefts were first treated by lip adhesion at age 3 months ( n = 3). In all patients, the lip was repaired at 3–6 months using a modified rotation-advancement technique. The palate was repaired in two stages with delayed hard palate closure. All 20 patients underwent a posterior palate repair at age 18 months and a hard palate repair at age 6 years. Ten patients underwent alveolar bone grafting at the time of mixed dentition using iliac crest bone graft. Six patients (30%) required a posterior pharyngeal flap to correct velopharyngeal insufficiency. 18 patients underwent lip/nose revision (1–3 times per patient), and the remaining 2 patients will need lip/nose revision after orthognathic surgery. Most patients ( n = 19, 95%) required midface surgery (4 received distraction osteogenesis and 15 Le Fort I osteotomy) to correct Class III malocclusion.

The anterior cranial base (S-N) and midface length (Ar-ANS, Ar-A) of median facial dysplasia patients were shorter than those of controls. Mandibular length (Ar-Go, Go-Gn) did not differ significantly between median facial dysplasia and control patients. Correspondingly, the jaw relations (ANS-N-Pog, NAPog) were smaller in median facial dysplasia patients than in controls. Also, the inter-orbital distance (Mo-Mo′, Lo-Lo′) was shorter and the nasal bone (S-N-N′) was more retrusive in median facial dysplasia patients than in controls ( Table 2 ).

Table 2
Comparison of craniofacial and dental morphology between median facial dysplasia and control patients.
Median facial dysplasia Controls
Morphological feature Median Range Median Range P
Calvarium
Ecc-Ecc’ (mm) 142.1 88–162 146.4 133–163 0.41
Cranial base
S-N (mm) 65.8 59–75 69.0 64–75 0.01
S-Ba (mm) 46.0 41–53 48.5 41–60 0.19
N-S-Ba (°) 130.5 120–144 132.0 122–141 0.70
Orbital cavity
Mo-Mo’ (mm) 23.5 15–31 26.2 23–31 0.01
Lo-Lo’ (mm) 88.3 63–101 93.8 87–100 0.01
Nasal bone
N-N’ (mm) 31.0 25–36 30.0 24–37 0.46
S-N-N’ (°) 91.0 80–101 98.0 81–123 < 0.01
Maxilla
Ar-ANS (mm) 74.5 59–93 83.5 79–93 < 0.001
Ar-A (mm) 74.0 59–90 80.8 75–91 < 0.001
N-ANS (mm) 56.3 50–71 57.3 48–65 0.53
R-PMP (mm) 51.0 43–60 49.0 45–61 0.42
S-N-ANS (°) 72.8 58–85 80.5 73–88 < 0.01
SNA (°) 72.3 59–83 77.3 72–87 0.01
Lpa-Lpa’ (mm) 36.4 27–52 36.3 27–89 0.80
Mx-Mx’ (mm) 64.2 57–74 68.4 56–78 0.18
Mandible
Ar-Go (mm) 45.8 39–72 46.3 36–54 0.56
Go-Gn (mm) 75.0 66–83 76.0 66–89 0.27
SNB (°) 77.0 71–84 77.0 70–88 0.73
S-N-Pog (°) 78.0 72–88 78.3 71–91 0.75
SN-MP (°) 35.5 17–51 35.0 23–51 0.66
Ag-Ag’ (mm) 93.2 79–103 93.0 82-103 0.66
Jaw relation
ANS-N-Pog (°) −5.0 −27 to 3 1.0 −11 to 8 0.01
ANB (°) −3.5 −24 to 2 −1.3 −10 to 6 0.06
NAPog (°) 169.0 129–184 177.0 154 to 192 0.03
Dentition
SN-UI (°) 97.0 70 to 111 97.3 79 to 131 0.32
LI-MP (°) 85.0 62 to 111 84.3 70 to 106 0.51
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Feb 5, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Craniofacial and dental dysmorphology in patients with median facial dysplasia: long-term follow-up
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