Invest Clin 65(3): 369 - 377, 2024 https://doi.org/10.54817/IC.v65n3a09
Corresponding author: Sergio Duarte-Inguanzo. Privada Los Pinos No. 7, Colonia Cañada de la Bufa, Guadalupe,
Zacatecas, México. México. Phone: +52-492-9229924. E-mail: sergio.duarteinguanzo@hotmail.com
Prediction of the individual response to
treatment of skeletal Class II malocclusions
and their long-term stability. A Case Report.
Sergio Duarte-Inguanzo1,2
, Aurora Duarte-López 3 , Olga Zambrano4
and Jesús A. Luengo-Fereira 5
1 Unidad Académica de Odontología, Universidad Autónoma de Zacatecas, Ciudad
de Zacatecas, México.
2 División de Estudios para Graduados, Facultad de Odontología, Universidad del Zulia.
Maracaibo, Venezuela.
3 Facultad de Odontología Unidad Saltillo, Maestría en Ortodoncia, Universidad
Autónoma de Coahuila, México.
4 Instituto de Investigaciones, Facultad de Odontología, Universidad del Zulia.
Maracaibo, Venezuela.
5 Unidad Académica de Odontología, Universidad Autónoma de Zacatecas, Ciudad
de Zacatecas, México.
Keywords: Class II; Herbst appliance; Baccetti and Franchi model.
Abstract. Non-surgical correction of class II skeletal malocclusions begins
at an early age, during the growth and development of the jaw. Treatments tend
to be relatively long and generate financial commitments for the family. Predict-
ing the success and stability of the results can be helpful for parents who wish to
know about the prognosis and make the right decision to start treatment. This
work reports the findings of the prediction of the response to treatment of a skel-
etal class II malocclusion and its long-term stability in a thirteen-year-old male
patient. The individual prediction cephalometric model of Baccetti and Franchi
was applied. According to this indicator, the treatment of this patient would re-
sult in “a great response”. The patient was treated with a Herbst-type fixed man-
dibular anterior projection appliance, followed by brackets for the final detailing
of the occlusion. Sixteen years later, after finishing treatment, the correction of
the Class II malocclusion, the overbite and the harmony in the profile with the
projection of the mandible forwards are maintained by the increase in the total
mandibular length (13 mm), and through the opening of the angle between the
ramus and mandibular body from 122° to 128°. In conclusion, the individual pre-
diction cephalometric model applied, particularly in this case report, allowed us
to accurately predict the excellent response and stability of the facial, dental and
skeletal results of the class II skeletal malocclusion treatment.

370 Duarte-Inguanzo et al.Investigación Clínica 65(3): 2024
Predicción de la respuesta al tratamiento de las maloclusiones
Clase II esqueléticas y su estabilidad a largo plazo.
Presentación de un caso.
Invest Clin 2024; 65 (3): 369 – 377
Palabras clave: cefalometría; aparato de Herbst, Modelo de Baccetti y Franchi.
Resumen. La corrección no quirúrgica de las maloclusiones esqueléticas
clase II se inicia en las edades tempranas, durante el crecimiento y desarrollo
de la mandíbula, suelen ser tratamientos relativamente largos y generar com-
promisos financieros para la familia. Predecir el éxito y la estabilidad de los re-
sultados puede resultar útil a los padres que desean saber sobre el pronóstico y
tomar la decisión para iniciar el tratamiento. Este trabajo reporta los hallazgos
de la predicción de la respuesta al tratamiento de una maloclusión clase II es-
quelética y su estabilidad a largo plazo, en un paciente masculino, de trece años
de edad. Se aplicó el modelo cefalométrico de predicción individual de Baccetti
y Franchi, y según este indicador, el tratamiento tendría “una gran respuesta”.
El paciente fue tratado con un aparato de proyección anterior mandibular fijo
tipo Herbst y apliques ortodóncicos para el detallado final de la oclusión. Die-
ciséis años después de finalizado el tratamiento, se mantuvo la corrección de la
maloclusión Clase II, la sobremordida horizontal y la armonía en el perfil con
la proyección de la mandíbula hacia adelante, mediante el aumento de la lon-
gitud total mandibular (13 mm), y por medio de la apertura del ángulo entre
rama y cuerpo mandibular de 122° a 128°. En conclusión, el modelo cefalomé-
trico de predicción individual aplicado particularmente en este reporte de caso
permitió predecir de manera acertada la buena respuesta y estabilidad de los
resultados faciales, dentales y esqueletales del tratamiento de la maloclusión
esquelética clase II.
Received: 28-01-2024 Accepted: 13-05-2024
INTRODUCTION
Class II malocclusion or skeletal distoc-
clusion significantly impacts function and
facial aesthetics. The prevalent diagnostic
finding in this type of malocclusion is man-
dibular skeletal retrusion, which is challeng-
ing to treat and has a high risk of relapse. 1
Various functional/orthopedic devices
for treating this malocclusion, among which
the Herbst and the Twin-Block, stand out
and have shown remarkable effectiveness 2
.
In a systematic review, Cozza et al. reported
substantial variabilities in the results of class
II treatments attributed to the type of device
used, duration of treatment, patient cooper-
ation, time of intervention, and the inherent
characteristics of the patient 3
. Similarly, Ca-
nut and Arias report that patients’ response
to this malocclusion treatment varies signifi-
cantly. Moreover, the nature of the variations
that induce the resolution of Class II with
functional devices is still unclear 4
. Petrovic
et al., in addition to other authors, affirm
that the effects of Class II therapy are much
more effective when carried out during the
peak of mandibular growth 5-7
. Saadia and
Valencia report that if the therapy is applied

Response to treatment of skeletal Class II malocclusions 371Vol. 65(3): 369 - 377, 2024
when biological events occur during growth
and craniofacial development processes, it
will have a more effective impact and less
tendency to relapse 8
. The success in treat-
ing skeletal malocclusions is determined by
the extent to which the correction is stable
in the long term 8,9 . Al Yami et al. reported
variable results between good and moderate
stability in 10-year post-treatment follow-ups
10
. Likewise, Bondemark et al., in a study on
the post-treatment stability of Class II ortho-
pedic therapies with Herbst-type appliances
in patients who received the treatment dur-
ing the pubertal growth peak, reported good
stability regarding facial characteristics;
however, they found recurrence regarding
the molar and canine relationship 11
.
Ruf and Pancherz report that the cor-
rection of skeletal Class II is more effective
if the Herbst appliance is combined with
multibracket treatment; in this way, a more
significant occlusal correction is achieved,
and they report stability for two years’ post-
treatment 12
. Tulloch et al. reported that in
younger patients treated, less recurrence
was observed than in those who received
treatment at an older age 13
. Failure can oc-
cur individually to different treatments and
similar protocols, even in patients who re-
ceive treatment under ideal conditions 8,9 .
The possibility of predicting with greater
certainty the prognosis of the results of a
skeletal Class II treatment and its long-term
stability could be an invaluable tool for the
clinician.
Previous studies have tried to find spe-
cific predictors to anticipate a successful
treatment; however, they have yet to be sys-
tematically validated 14-16
. Some authors af-
firm that a Class II patient at the peak of
pubertal growth with a closed gonial angle
of the mandible will react successfully to
functional orthopedic treatment 7,17 . In this
regard, Baccetti and Franchi proposed a
cephalometric model to predict individually
the response to treatment of a skeletal Class
II malocclusion with functional jaw orthope-
dics. They analyzed various cephalometric
parameters, noting that only the angular re-
lationship between the ramus and the man-
dibular body represents the indicator with
predictive power 18
.
This work aimed to report the predic-
tion of the response to treatment of a skel-
etal Class II malocclusion and its long-term
stability using the Baccetti and Franchi
cephalometric model 18
.
CASE PRESENTATION
This is the case of a 13-year-old male
patient who attended the orthodontic ser-
vice at the Piezzo Dental Clinic in Zacatecas,
Mexico. Informed consent to participate in
the study was obtained from the patient and
his representatives, and the authorization
to publish his photograph in this study. He
presented with no medical history of inter-
est, euryprosopic facial type, a symmetrical,
slightly enlarged lower facial third, convex
profile, short chin-neck distance, lip incom-
petence, open nasolabial angle, and closed
mentolabial angle (Fig. 1a). Permanent den-
tition, Class II molar and bilateral canine, 14
mm overjet, and 30% overbite. A triangular
symmetric upper dental arch; square asym-
metric lower arch, upper and lower crowd-
ing; a severe curve of Spee (Fig. 2a); and
cervical vertebral maturation stage CS3 19
.
The cephalometric analysis determined
a skeletal Class II mandibular hypoplasia20
(Fig. 3a). The value of the predictive angu-
lar measurement (Co-Go-Me°) was 122°;
therefore, according to the model, the pa-
tient would have a “great response” to treat-
ment 18 (Fig. 4).
The patient was treated with a fixed
Herbst-type mandibular anterior projec-
tion appliance with bands for one year and
five months to position the mandible in
a molar and canine Class I (Fig. 2b) and a
straight profile until the end of the mandibu-
lar growth peak CS4 and the beginning of
CS5 19
, at 14 years and eight months of age
(Fig. 1b). In the second phase, complete
brackets were placed for one year, and Class

372 Duarte-Inguanzo et al.Investigación Clínica 65(3): 2024
Fig. 1. Front and profile photographs: (1a) pre-treatment at 13 years and three months of age; (1b) after Her-
bst therapy at 14 years and eight months of age; (1c) at the end of bracket treatment at 15 years and
eight months of age; (1d) 16 years after treatment completion at 31 years and nine months of age.
1a1b1c1d
Fig. 2. Intraoral photographs, Right Lateral, Frontal, and Left Lateral Views: (2a) Pre-treatment at 13 years
and three months of age; (2b) after Herbst therapy at 14 years and eight months of age; (2c) at the
end of bracket treatment at 15 years and eight months of age; (2d) 16 years after treatment comple-
tion at 31 years and nine months of age.2a2b2c2d

Response to treatment of skeletal Class II malocclusions 373Vol. 65(3): 369 - 377, 2024
Fig. 3. (3a) Initial Cephalometry; (3b) After treatment; (3c) 16 years post-treatment…
Cephalometric
Measurements Norma
Initial pre-
treatment
measurement
(3a)
End of treatment
measurement (3b)
16 years post-
treatment (3c)
Convexity (A/B-Pg) 2mm 9mm 1mm -1mm
Maxillary Deepness (PoOr-NaA) 90° 89° 89° 90°
Facial Deepness (Po-Or/N-Pg) 87° 75° 86° 88°
Mandibular Plane (Go-Me/Po-Or) 26° 30° 27° 29°
Upper Incisor / N-A 22° 25° 25° 23°
Lower Incisor / Mandibular Plane 90° 84° 89° 92°
Mandibular Arch (Dc-XI/XI-Pm) 29° 34° 28° 30°
Mandibular Body Lenght(XI-Pm) 69 mm 67 mm 68mm 70mm
Total Mandibular Length (Co-Gn) 132mm 121mm 131mm 134mm
Favorably Response
Co-Go-Me 122°
The measure of the prediction was
122°, 2° below 124°, which means it will
have a great response to treatment.
Fig. 4. Tracing of the Condylion, Gonion, Menton (Co-Go-Me) planes to form the predictive angle according
to Baccetti and Franchi’s individual prediction cephalometric model.3a3b3c

374 Duarte-Inguanzo et al.Investigación Clínica 65(3): 2024
II intermaxillary ligatures were used for four
months (Fig. 2c). The profile and facial har-
mony were further improved at the end of
this phase (Fig. 1c). Finally, a containment
period was carried out for one year with
Hawley-type removable retainers, worn 24
hours a day for six months, followed by six
months of only night use, and the patient
was discharged. Appointments were held
every three years to monitor the stability of
the results.
Intraorally, the molar and canine
Class II changed to Class I (Fig. 2c). Post-
treatment cephalometry, in general terms,
showed a remarkable correction of skeletal
Class II and harmonization in profile 20
. Most
notable was the 6° increase in angulation be-
tween the ramus and the mandibular body,
thus increasing the total mandibular length
by 10 mm (Fig. 3b).
At the age of 31 years, new records were
taken: extra orally, greater harmony was ob-
served in the facial contour, proportioned
thirds, and straight and balanced profile
(Fig. 1d). Intra orally, a Class I molar and ca-
nine occlusion with solid interdigitation on
both sides, 2 mm overjet, and 30% overbite
were observed (Fig. 2d).
Cephalometrically, a relevant value was
the increase in total mandibular length of
3 mm in these 16 years after finishing the
Fig. 5. Superimposition of the mandible (Continuous line: 13 years three months of age - Dotted line: 31
years nine months of age).
Increase in Co-Gn
(16 years Post-treatment) +13 mm
treatment, thus maintaining a balanced pro-
file 20 (Fig. 3c).
A superimposition shows us that 16
years after treatment, the total mandibu-
lar length alone increased by 3 mm more,
reaching a total increase of 13 mm since the
beginning of treatment (Fig. 5).
DISCUSSION
This paper reports the prediction of the
response to treatment and its long-term sta-
bility by applying the Baccetti and Franchi
18 model in an adolescent with skeletal class
II malocclusion, treated with a Herbst-type
fixed appliance and the use of brackets for
the final detailing of the occlusion.
The study by Baccetti and Franchi 18
identified the Co-Go-Me angle with a predic-
tive power of 80.4% reliability. According to
this model, a Co-Go-Me angle between 124°
and 128.5° will respond favorably to orthope-
dic therapy; a Co-Go-Me angle greater than
128.5° will react unfavorably to therapy; and
those patients who initially present a Co-
Go-Me angle of less than 124° will have a
great response to treatment; however, these
authors did not present long-term stability
results. In the present report, this measure
(122°) correctly predicted the largely favor-
able response to treatment.

Response to treatment of skeletal Class II malocclusions 375Vol. 65(3): 369 - 377, 2024
This prediction model determines that
the shape of the mandible, specifically the
angular relationship between the ramus and
the body, plays a more critical role as an indi-
cator of treatment prognosis than the posi-
tion of the mandible in relation to other cra-
niofacial structures. Other authors report
similar findings 14,15
.
Van Limborgh and Enlow 21 described
that the mandible has growth control with
a more significant genetic load than the
maxilla; therefore, there is less possibility
of changes under environmental influences.
However, the rotations between the ramus
and mandibular body and the redirection of
condylar growth are susceptible to chang-
es determined by environmental factors or
therapeutic actions 21
. In skeletal Class II
malocclusion due to mandibular hypoplasia,
the therapeutic solution is the elongation of
the mandible to bring forward its body and
the chin, and this can be achieved by gen-
erating, with the treatment, a descending
intra-matrix rotation between the ramus
and the mandibular body; that is, opening
precisely the angle between these two struc-
tures, consequently increasing the distance
between the condyle and the chin, and there-
fore increasing the total mandibular length 2
.
So, if the mandible initially presents an open
angle between the ramus and the body, the
prognosis could be unfavorable, since it
would have less possibility of opening further
and lengthening the mandible forward (it is
as if a hinge were opening). Therefore, it is
necessary that this angle initially be closed 5
.
Cozza et al. suggest that a closed man-
dibular angle before treatment correlates
with evidence of better responsiveness to
orthopedic treatment to increase total
mandibular length and vice versa. At the
start of treatment, a patient with an open
angle between the ramus and the mandibu-
lar body will be less likely to attain elonga-
tion through orthopedic therapy 3
. Likewise,
Petrovic et al. state that the potential re-
sponsiveness to orthopedic therapy aimed at
stimulating growth in the mandibular con-
dyle is significantly more significant in the
presence of anterior growth rotation of the
mandible than in a posterior growth rotation
5
. In the case of the current study, the patient
initially presented a significantly closed Co-
Go-Me mandibular angle and a notable ante-
rior rotation of the mandible. On the other
hand, Proffit and Saadia define a good re-
sponse to orthopedic therapy as one that is
maintained in the long term 8,9 . Canut et al.
state that there is a high risk of recurrence
in skeletal Class II treatments; however, in
some cases, it is possible to maintain stable
long-term favorable treatment results, free
of recurrence and containment 4
.
In the case described in this report,
after completing the comprehensive treat-
ment, the patient only used removable re-
tainers for one year with discontinuous use
over time. The remaining time, the patient
remained free of containment and relapse.
Ruf and Pancherz report good results in
occlusal correction and stability of the treat-
ment of skeletal Class II; they attribute this
to the simultaneous application of full brack-
et and Herbst appliances 12
. In the patient of
the present report, occlusal correction and
excellent stability were achieved by combin-
ing complete brackets and Herbst. Ruf and
Pancherz12 made the stability evaluation two
years after treatment, unlike in the case pre-
sented in this report, where the evaluation
was performed 16 years after finishing the
treatment.
Bondemark reports post-treatment
stability in facial characteristics but not
in occlusion or cephalometric data 11
. The
present report maintained favorable facial,
dental, and cephalometric changes; more-
over, a better and more detailed occlusal
interdigitation was achieved with time. This
refinement was self-formed. Likewise, the fa-
cial profile reached a better balance and har-
mony, so it can be inferred that growth and
development alone have the capacity for self-
improvement in cases like this when they are
helped at a specific moment through a treat-
ment that creates a suitable scenario.

376 Duarte-Inguanzo et al.Investigación Clínica 65(3): 2024
Tulloch et al. state that the earlier the
age at which treatment is started, the more
stable it will be, and vice versa 13
. This state-
ment sounds somewhat ambiguous since
they do not mention the specific age. In
our case, Herbst therapy was started at the
beginning of the CS3 19 mandibular growth
peak.
In conclusion, Baccetti and Franchi’s
prediction model for Class II malocclusion
correction predicted the response to treat-
ment in this particular patient, which was
confirmed and resulted in long-term stable
facial and dental skeleton changes.
ACKNOWLEDGMENT
We thank Dr. Humberto Martínez for his
contribution to editing and translating the
manuscript and Carlos E. Duarte-Hernández
for searching bibliographic references.
Funding
This study was not funded.
Conflicts of interest
The authors reported no potential con-
flict of interest.
Authors’ ORCID number
• Sergio Duarte-Inguanzo (SD):
0009-0008-7877-5574
• Aurora Duarte-López (AD):
0009-0005-0386-1046
• Olga Zambrano (OZ):
0000-0003-4867-2351
• Jesús A. Luengo-Fereira (JL):
0000-0002-2780-5496
Authors’ contribution
SD: Treatment and clinical and radio-
graphic follow-up of the case. Conception,
design, analysis, and interpretation of data,
editing, review, and approval of the final
version of the manuscript to be published.
Funding support. AD: Analysis and interpre-
tation of data, editing, review, and approval
of the final version to be published. OZ: Con-
ception, design, analysis, and interpretation
of data, editing, critical review, and appro-
val of the final version to be published. JL:
Analysis and interpretation of data, critical
review, and approval of the final version to
be published.
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