Table 1.
Speech evaluations and results by malocclusion type.
| Author, Year, and Language | Sample Size, DFD Groups and Ages | Methods Used | Preoperative Findings | Timepoints Evaluated | Postoperative Findings |
|---|---|---|---|---|---|
| DFD Group: Class III | |||||
| Ahn et al., 2015 [52] Language: Korean |
N = 16 Class III n = 8 Controls* n = 8 Ages 18–26 |
Formant analysis of vowels | Class III DFD patients used an area of the formant graph 133.44% larger than the controls. | Presurgery, 6 weeks, 3 and 6 months postsurgery | F1 and F2 formants of Class III patients reduced in vowels [a], [i], [e], and [æ] by 6 months postsurgery; articulating positions shifted. |
| Bruce and Hanson, 1987 [53] Language: English |
N = 4 Class III n = 3 Asymmetry n = 1 No controls Ages 16–43 |
Perceptual evaluation of recordings; tongue thrust evaluation | 100% of DFD patients presented with a lisp and tongue thrust. Distortions were seen in [s] and [z] sounds. | Presurgery, 9 weeks postsurgery | Correction of speech in 50% of patients, 25% of those with tongue thrust improved. |
| Ghaemi et al., 2021 [54] Language: Persian |
N = 20 Class III n = 20 No controls Ages 18–40 |
Perceptual evaluation of recordings; formant analysis of vowels | 95% of Class III DFD patients produced distortions in consonant sounds [ʃ] and [s]. Distortions were also present in [ɹ] and [z] sounds in the majority of participants. | Presurgery, 1 and 6 months postsurgery | All articulation errors eliminated by 6 months postoperatively; speech intelligibility increased to 100% at 6 months postsurgery. |
| Glass et al., 1977 [55] Language: English |
N = 5 Class III n = 5 No controls Ages 18–54 |
Perceptual evaluation of recordings | All Class III DFD patients had speech articulation distortions. | Presurgery, 2 months postsurgery | Decrease in sibilant distortions in 100% of patients. |
| Goodstein et al., 1974 [56] Language: English |
N = 10 Class III n = 5 Controls n = 5 Ages: N/A |
Perceptual evaluation of recordings | 100% of Class III DFD patients had preoperative speech errors. | Presurgery, splint removal, 2 months postsurgery | More fluent speech postoperatively, but no significant changes in speech pattern in 100% of Class III patients. |
| Guay et al., 1978 [57] Language: English |
N = 12 Class III n = 12 No controls Mean age: 13 |
Live perceptual evaluation; cephalometric analysis | 92% of Class III patients had some degree of distortion of [s]. Tongue posture at rest was lower than normal. | Presurgery | NA: Postoperative outcomes were not studied. |
| Lathrop-Marshall et al., 2022 [26] Language: English |
N = 164 Class III n = 102 Controls n = 62 Ages 14–40 |
Perceptual evaluation of recordings; cephalometric analysis; spectral moment analysis | Severity of malocclusion correlated with distortion of [t] and [tʃ] in Class III patients. | Presurgery | NA: Postoperative outcomes were not studied. |
| Weimer and Astrand, 1977 [58] Language: Swedish |
N = 30 Class III n = 30 No controls Ages 18–45 |
Perceptual evaluation of recordings | Mild speech defects were seen in 17% of Class III DFD patients preoperatively; 83% of the patients were considered to have normal speech. | Presurgery, 6 months postsurgery | 60% of patients with preoperative speech defects had correction in speech, 40% of those patients experienced slight improvement in speech. |
| DFD Group: Class II | |||||
| Garber et al., 1981 [59] Language: English |
N = 6 Class II n = 6 No controls Ages 14–24 |
Perceptual evaluation of recordings; cephalometric analysis | Average of 35 errors in speech were noted during the presurgical recordings among Class II DFD patients. | Presurgery, 5 days; 1, 3, 6, and 12 months postsurgery | Speech deterioration was noted immediately after surgery, predominantly in phoneme [s]; there was overall improvement long-term after surgery. |
| Niemi et al., 2006 [60] Language: Finnish |
N = 5 Class II n = 5 No controls Ages 31–42 |
Formant analysis of vowels; cephalometric analysis | None of the subjects had speech disorders or difficulties despite having DFD. | Presurgery, 6 and 30 weeks postsurgery | No significant long-lasting changes were found postoperatively. |
| DFD Group: Anterior Open Bite (AOB) | |||||
| Keyser et al., 2022 [19] Language: English |
N = 101 AOB n = 39 Controls n = 62 Ages 14–40 |
Perceptual evaluation of recordings; spectral moment analysis; cephalometric analysis | Higher prevalence of distorted [s] found in AOB patients. | Presurgery | NA: Postoperative outcomes were not studied. |
| Knez Amrožič et al., 2015
[21] Language: Slovenian |
N = 15 AOB n = 15 No controls Ages 18–32 |
Formant analysis of vowels; cephalometric analysis | 60% of AOB DFD patients had articulation disorders. | Presurgery, 6 months postsurgery | No significant changes were found postoperatively. |
| Kravanja et al., 2018 [61] Language: Slovenian |
N = 75 AOB n = 32 Controls n = 43 Ages 3–7 |
Live perceptual evaluation; ultrasound imaging of tongue | 84% of AOB patients had articulation disorders and 81% of AOB patients had abnormal tongue posture. | Presurgery | NA: Postoperative outcomes were not studied. |
| Turvey et al., 1976 [62] Language: English |
N = 9 Class III/AOB n = 2 Class II/AOB n = 4 Class I/AOB n = 3 No controls Ages 14–27 |
Live perceptual evaluation; cephalometric analysis; tongue thrust evaluation | 89% of DFD patients presented with perceptible lisping preoperatively. | Presurgery, 3-, 6- and 12-months postsurgery | 78% had improvement in lisping; all patients improved in tongue function. |
| DFD Group: Multiple Malocclusions | |||||
| Bowers et al., 1985 [63] Language: English |
N = 5 Class III n = 2 Class II n = 3 No controls Ages 17–22 |
Perceptual evaluation of recordings; formant analysis of vowels | All patients had perceptually normal speech preoperatively. | Preorthodontic treatment, presurgery, postsurgery, postdebonding | Significant frequency shift for [e]; speech was perceptually normal postoperatively. |
| Buyuknacar et al., 1993 [50] Language: Turkish |
N = 60 Class III n = 20 Class II n = 20 Controls n = 20 Mean age: 14 |
Spectral moment analysis; cephalometric analysis | Center of gravity for [s] was lower in Class II patients compared with others. No evidence for correlation between malocclusion and speech disorder. | Presurgery | NA: Postoperative outcomes were not studied. |
| Dalston and Vig, 1984 [64] Language: English |
N = 40 Class III n = 25 Class II n = 15 No controls Ages N/A (adults) |
Perceptual evaluation of recordings; velopharyngeal evaluation; cephalometric analysis | More than half of the errors were made by 20% of all patients. Most of the errors were distortions of [s] and [z]. | Presurgery, 6 and 12 months postsurgery | Nasal–oral coupling and nasal resistance significantly improved; no significant perceptual changes in speech postoperatively. |
| Geffen, 1978 [65] Languages: English and Afrikaans |
N = 9 Class III n = 6 Class II n = 2 Asymmetry n = 1 No controls Ages N/A (adults) |
Perceptual evaluation of recordings; cephalometric analysis | 67% of Class III DFD patients had distortions of [s]. All Class II and asymmetric patients had distortions of the [s] sound. | Presurgery, 3–11 months postsurgery | 22% had improvement in articulation of [s] phoneme; 55% had improvement in general quality of speech; articulating positions shifted. |
| Laine, 1992 [66] Language: Finnish |
N = 451** Class III n = 25 Class II n = 70 AOB n = 40 Controls n = 90 Other n = 226 Mean age: 23 |
Perceptual evaluation of recordings | 53% of Class III, Class II and AOB patients had speech disorders; most common disorders being those produced anterior to the correct location of articulation. | Presurgery | NA: Postoperative outcomes were not studied. |
| Leavy et al., 2016 [20] Language: English |
N = 115 Class III n = 8 Class II n = 47 AOB n = 31 Controls n = 60 Ages 8–36 |
Perceptual evaluation of recordings | 62% of all subjects (with or without malocclusions) had articulatory distortions, mainly of [s] and [t] sounds; more severe malocclusion, more likely to have a speech distortion. | Presurgery | NA: Postoperative outcomes were not studied. |
| Lichnowska et al., 2021 [67] Language: Polish |
N = 37 Class III n = 28 Class II n = 9 No controls Ages 18–50 |
Perceptual evaluation of recordings; tongue thrust evaluation | 100% of patients presented with articulation concerns (by inclusions criteria); distortions in Class III patients were worse than in Class II. | Presurgery | NA: Postoperative outcomes were not studied. |
| Oliver et al., 2022 [44] Language: English |
N = 227 Class III n = 102 Class II n = 53 Controls n = 72 Ages 12–37 |
Perceptual evaluation of recordings; spectral moment analysis | Greater occurrence of distortions among Class II DFD patients compared with controls; lower consonant spectral moments for Class II compared with Class III and AOB DFD patients. | Presurgery | NA: Postoperative outcomes were not studied. |
| Ruscello, 1986 [68] Language: English |
N = 20 Class III n = 11 Class II n = 3 Asymmetry n = 2 Maxillary Excess n = 4 No controls Ages 17–53 |
Perceptual evaluation of recordings | About 60% of all DFD patients exhibited preoperative articulation errors. | Presurgery, splint removal, 3 and 6 months postsurgery | 42% (of those with errors prior to surgery) showed reduction in errors postoperatively; 17% remained unchanged. |
| Vallino, 1990 [69] Language: English |
N = 34 Class III n = 11 Class III/AOB n = 5 Class II n = 23 Class II/AOB n = 12 No controls Ages 14–48 |
Live perceptual evaluation; velopharyngeal evaluation | 88% of all DFD patients showed articulation errors with distortions of sibilants [s] and [z] being the most commonly observed. | Presurgery, 3, 6, 9, and 12 months postsurgery | 57% (of those with errors prior to surgery) experienced correction of speech; 43% improved; surgery did not impact velopharyngeal area. |
| Vallino et al., 1993 [48] Language: English |
N = 33 Class III n = 6 Class III/AOB n = 4 Class II n = 12 Class II/AOB n = 11 No controls Ages 14–39 |
Live perceptual evaluation; cephalometric analysis | 88% of all patients had articulatory distortions; most of them associated with sibilant sounds [s] and [z]. | Presurgery | NA: Postoperative outcomes were not studied. |
| Wakumoto et al., 1996 [70] Language: Japanese |
N = 5 Class III n = 3 Class II n = 2 No controls Ages 17–31 |
Electropalatography; spectral peak analysis | None of the patients had preoperative speech disorders when judged by an SLP. | Preorthodontic treatment, presurgery, 3 and 6 months postsurgery | Articulating positions shifted for 100% of patients; significant acoustic changes in 40% of patients. |
| Ward et al., 2002 [71] Language: English |
N = 13 Class III n = 1 Class III/AOB n = 1 Class II n = 3 Controls n = 8 Ages 15–21 |
Perceptual evaluation of recordings; velopharyngeal evaluation | 80% of Class III, Class III/AOB and Class II DFD patients had articulatory distortions of lingual alveolar and palatal sibilants. | Presurgery, 6 months postsurgery | 25% (of those with errors prior to surgery) improved in articulation; 60% had improved interlabial pressures. |
| Witzel et al., 1980 [72] Language: English |
N = 41 Class III n = 4 Class III/AOB n = 7 Class II n = 12 Class II/AOB n = 17 AOB n = 1 No controls Ages 9–26 |
Live perceptual evaluation | 54% of DFD patients showed articulation errors. All groups had distortions of sibilants (except the patient with apertognathia). Labiodental distortions were noted in Class III patients. Bilabial sound distortions were noted in Class II patients. | Presurgery, 6 months postsurgery | 64% (of those with errors prior to surgery) saw correction of speech; 36% of those saw improvement in speech. |
*
Control = Class I, no AOB.
**
Occlusal classifications reported.