Lorenzo Franchi

An Improved Version of the Cervical Vertebral Maturation (CVM) Method for the Assessment of Mandibular Growth

The present study aimed to provide a version of the Cervical Vertebral Maturation (CVM) method for the detection of the peak in mandibular growth based on the analysis of the second through fourth cervical vertebrae in a single cephalogram. The morphology of the bodies of the second (odontoid process, C2), third (C3), and fourth (C4) cervical vertebrae were analyzed in six consecutive cephalometric observations (T1 through T6) of 30 orthodontically untreated subjects. Observations for each subject consisted of two consecutive cephalograms comprising the interval of maximum mandibular growth (as assessed by means of the maximum increment in total mandibular length, Co-Gn), together with two earlier consecutive cephalograms and two later consecutive cephalograms. The analysis consisted of both visual and cephalometric appraisals of morphological characteristics of the three cervical vertebrae. The construction of the new version of the CVM method was based on the results of both ANOVA for repeated measures with post-hoc Scheffés test (P < .05) and discriminant analysis. The new CVM method presents with five maturational stages (Cervical Vertebral Maturation Stage [CVMS] I through CVMS V, instead of Cvs 1 through Cvs 6 in the former CVM method). The peak in mandibular growth occurs between CVMS II and CVMS III, and it has not been reached without the attainment of both CVMS I and CVMS II. CVMS V is recorded at least two years after the peak. The advantages of the new version of the CVM method are that mandibular skeletal maturity can be appraised on a single cephalogram and through the analysis of only the second, third, and fourth cervical vertebrae, which usually are visible even when a protective radiation collar is worn.

Skeletal effects of early treatment of Class III malocclusion with maxillary expansion and face-mask therapy

The effectiveness of maxillary expansion and face-mask therapy in children with Class III malocclusion was studied in a sample of 46 subjects in mixed dentition and compared with a control sample of 32 subjects with untreated Class III malocclusion. Treated and untreated samples were divided into early and late mixed-dentition groups to aid identification of the optimum timing of the orthopedic treatment of the underlying skeletal disharmony. Cephalometric analysis was based on a stable basicranial reference system, appropriate for longitudinal studies started in the early developmental ages. The level of significance for intergroup comparisons was set at a p value of 0.01. Significant forward displacement of the maxillary complex was found in the early-treatment group. The region of the pterygomaxillary suture, in particular, showed significant changes in the subjects treated during early mixed dentition. No significant maxillary modifications were recorded in the late-treatment group. Both early and late groups exhibited smaller increments in mandibular protrusion and larger increments in the intermaxillary vertical relationship compared with their respective Class III control groups. Only children treated at an early age, however, showed a significant upward and forward direction of condylar growth, leading to smaller increments in total mandibular length. These results indicate that the combination of a bonded maxillary expander and face-mask therapy is more effective in early mixed dentition than in late mixed dentition, especially with regard to the magnitude of the protraction effects on maxillary structures.

Treatment Timing for Rapid Maxillary Expansion

The aim of this study was to evaluate the short-term and long-term treatment effects of rapid maxillary expansion in 2 groups of subjects treated with the Haas appliance. Treatment outcomes were evaluated before and after the peak in skeletal maturation, as assessed by the cervical vertebral maturation (CVM) method, in a sample of 42 patients compared to a control sample of 20 subjects. Posteroanterior cephalograms were analyzed for the treated subjects at T1 (pretreatment), T2 (immediate post-expansion) and T3 (long-term observation), and were available at T1 and at T3 for the controls. The mean age (years: months) at T1 was 11:10 for both the treated and the control groups. The mean ages at T3 also were comparable (20:6 for the treated group and 17:8 for the controls). Following expansion and retention (2 months on average), fixed standard edgewise appliances were placed. The study included transverse measurements on dentoalveolar structures, maxillary and mandibular bases and other craniofacial regions (nasal, zygomatic, orbital, and cranial). Treated and control samples were divided into 2 groups according to individual skeletal maturation. The early-treated and early-control groups had not reached the pubertal peak in skeletal growth velocity at T1 (CVM 1 to 3), whereas the late-treated and late-control groups were during or slightly after the peak at T1 (CVM 4 to 6). The group treated before the pubertal peak showed significantly greater short-term increases in the width of the nasal cavities. In the long-term, maxillary skeletal width, maxillary intermolar width, lateronasal width, and lateroorbitale width were significantly greater in the early-treated group. The late-treated group exhibited significant increases in lateronasal width and in maxillary and mandibular intermolar widths. Rapid Maxillary Expansion treatment before the peak in skeletal growth velocity is able to induce more pronounced transverse craniofacial changes at the skeletal level.

Early dentofacial features of Class II malocclusion: A longitudinal study from the deciduous through the mixed dentition☆☆☆★★★♢♢♢

A group of 25 untreated subjects with Class II malocclusion in the deciduous dentition (featuring the concomitant presence of distal step, Class II deciduous canine relationship, and excessive overjet) was compared with a control group of 22 untreated subjects with ideal occlusion (flush terminal plane, Class I deciduous canine relationship, minimal overbite, and overjet) at the same dentitional stage. The subjects were monitored during a 2 1/2-year period in the transition from the deciduous to the mixed dentition, during which time no orthodontic treatment was provided. Occlusal analysis of the Class II group in the deciduous dentition revealed an average interarch transverse discrepancy due to a narrow maxillary arch relative to the mandible. All occlusal Class II features were maintained or became exaggerated during the transition to the mixed dentition. The skeletal pattern of Class II malocclusion in the deciduous dentition typically was characterized by significant mandibular skeletal retrusion and mandibular size deficiency. During the period examined, cephalometric changes consisted of significantly greater maxillary growth increments and smaller increments in mandibular dimensions in the Class II sample. Moreover, a greater downward and backward inclination of the condylar axis relative to the mandibular line, with consequent smaller decrements in the gonial angle, were found in the Class II group, an indication of posterior morphogenetic rotation of the mandible in patients with Class II malocclusion occurring during the period examined. The results of this study indicate that the clinical signs of Class II malocclusion are evident in the deciduous dentition and persist into the mixed dentition. Whereas treatment to correct the Class II problem can be initiated in all three planes of space (e.g., RME, extraoral traction, functional jaw orthopedics), other factors such as patient cooperation and management must also be taken into consideration before early treatment is started.

Rapid maxillary expansion followed by fixed appliances: a long-term evaluation of changes in arch dimensions.

The purpose of this longitudinal study was to evaluate the short- and long-term changes in dental arch dimensions in patients treated with rapid maxillary expansion (RME) followed by fixed edge-wise appliances. The records of 112 patients in the treated group (TG) were compared with those of 41 untreated controls. Serial dental casts were available at three different intervals: pretreatment (T1), after expansion and fixed appliance therapy (T2), and at long-term observation (T3). The mean duration of the T1-T2 and T2-T3 periods for the TG group was three years two months +/- five months and six years one month +/- one year two months, respectively. Treatment by RME followed by fixed appliances produced significantly favorable short- and long-term changes in almost all the maxillary and mandibular arch measurements. In comparison with controls, a net gain of six mm was achieved in the maxillary arch perimeter, whereas a net gain of 4.5 mm was found for the mandibular arch perimeter of treated subjects in the long term. The duration of retention with a fixed lower appliance in the posttreatment period did not appear to affect the long-term outcomes of the treatment protocol significantly. The amount of correction in both maxillary and mandibular intermolar widths equaled two-thirds of the initial discrepancy, whereas treatment eliminated the initial deficiency in maxillary and mandibular intercanine widths. The amount of correction for the deficiency in maxillary arch perimeter was about 80%, whereas in the mandible a full correction was achieved.

Longitudinal growth changes in untreated subjects with Class II Division 1 malocclusion

INTRODUCTION The purpose of this longitudinal study was to compare the craniofacial growth changes in untreated subjects with Class II Division 1 malocclusion with those in subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development, as defined by a biological indicator of individual skeletal maturity (cervical vertebral maturation method). METHODS The Class II Division 1 sample consisted of 17 subjects (11 boys, 6 girls). The Class I sample also consisted of 17 subjects (13 boys, 4 girls). The lateral cephalograms of the subjects in both groups were analyzed at 6 consecutive stages of development, from CS1 through CS6. The statistical comparisons of the growth changes in the study groups were performed with Mann-Whitney U tests. RESULTS Craniofacial growth in subjects with untreated Class II malocclusion is essentially similar to that in untreated subjects with normal occlusion at all developmental intervals, with the exception of significantly smaller increases in mandibular length (P <0.001) at the growth spurt (interval CS3-CS4) and during the overall observation period (intervals CS1-CS6). CONCLUSIONS Class II dentoskeletal disharmony does not tend to self-correct with growth in association with worsening of the deficiency in total mandibular length and mandibular ramus height.

Treatment and posttreatment effects of acrylic splint Herbst appliance therapy.

This study evaluated the skeletal and dentoalveolar changes induced by acrylic splint Herbst therapy of Class II malocclusion. The treated group comprised 55 subjects with Class II malocclusion treated with the acrylic splint Herbst appliance followed by comprehensive edgewise therapy. The mean age at Time 1 (immediately before treatment) was 12 years and 10 months +/- 1 year and 2 months. The mean age at Time 2 (immediately after debonding of the Herbst appliance) and Time 3 (posttreatment) was 13 years and 10 months +/- 1 year and 2 months and 15 years and 2 months +/- 1 year and 4 months, respectively. The two control groups were one group of 30 subjects with untreated Class II malocclusion and another group of 33 subjects with Class I occlusion. The three groups were homogeneous as to the stage of maturation of cervical vertebrae at all observation times. A modification of Pancherzs cephalometric analysis was applied to the lateral cephalograms of the three groups at Time 1, Time 2, and Time 3. Linear and angular measurements for mandibular dimensions, cranial base angulation, and vertical relationships were added to the original analysis. Differences for all the variables from Time 1 to Time 2 (active treatment effects), from Time 2 to Time 3 (posttreatment effects), and from Time 1 to Time 3 (overall treatment effects) were calculated for the treated group and contrasted to corresponding differences of both untreated groups by means of ANOVA (P <.05). The study showed that two thirds of the achieved occlusal correction was due to skeletal effects and only one third to dentoalveolar adaptations. Both skeletal and dentoalveolar effects were due mainly to changes in mandibular structures. A significant amount of relapse in molar relationship occurred during the posttreatment period, and this change could be ascribed to the mesial movement of the upper molars.

Long-term Effectiveness and Treatment Timing for Bionator Therapy

The aim of the present investigation was to provide information about the long-term effects and optimal timing for class-II treatment with the Bionator appliance. Lateral cephalograms of 23 class-II patients treated with the Bionator were analyzed at three time periods: T1, start of treatment; T2, end of Bionator therapy; and T3, long-term observation (after completion of growth). T3 includes a phase with fixed appliances. The treated sample was divided into two groups according to their skeletal maturity as evaluated by the cervical vertebral maturation (CVM) method. The early-treated group (13 subjects) initiated treatment before the peak in mandibular growth, which occurred after completion of Bionator therapy. The late-treated group (10 subjects) received Bionator treatment during the peak. The T1-T2, T2-T3, and T1-T3 changes in the treated groups were compared with changes in control groups of untreated class-II subjects by nonparametric statistics (P < .05). The findings of the present study on Bionator therapy followed by fixed appliances indicate that this treatment protocol is more effective and stable when it is performed during the pubertal growth spurt. Optimal timing to start treatment with the Bionator is when a concavity appears at the lower borders of the second and the third cervical vertebrae (CVMS II). In the long-term, the amount of significant supplementary elongation of the mandible in subjects treated during the pubertal peak is 5.1 mm more than in the controls, and it is associated with a backward direction of condylar growth. Significant increments in mandibular ramus height also were recorded.

Role of posterior transverse interarch discrepancy in Class II, Division 1 malocclusion during the mixed dentition phase

Posterior transverse interarch discrepancy (PTID), measured as the difference between the maxillary and mandibular intermolar widths, was investigated in a sample of 60 Class II, Division 1 subjects during the mixed dentition phase. Two main groups were detected: Class II group 1 (30 subjects) with PTID and Class II group 2 (30 subjects) without PTID. A sample of 30 Class I subjects in the mixed dentition phase was used as a control group. In Class II group 1, PTID was found to be due to a significantly narrower maxillary arch. The craniofacial skeletal features of both Class II groups and of the Class I group were assessed. The Class II group with PTID showed mandibular retrusion associated with a posteriorly displaced mandible of normal size (functional mandibular retrusion). The Class II group without PTID had mandibular retrusion due to a micrognathic mandible (anatomic mandibular retrusion). The relevance of these findings for treatment planning in Class II, Division 1 malocclusion in the mixed dentition was stressed.

Comparison of two protocols for maxillary protraction: Bone anchors versus face mask with rapid maxillary expansion

OBJECTIVE To test the hypothesis that there is no difference in the active treatment effects for maxillary advancement induced by bone-anchored maxillary protraction (BAMP) and the active treatment effects for face mask in association with rapid maxillary expansion (RME/FM). MATERIALS AND METHODS This is a study on consecutively treated patients. The changes in dentoskeletal cephalometric variables from start of treatment (T1) to end of active treatment (T2) with an average T1-T2 interval of about 1 year were contrasted in a BAMP sample of 21 subjects with a RME/FM sample of 34 patients. All subjects were prepubertal at T1. Statistical comparison was performed with t-tests for independent samples. RESULTS The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy (with a difference of 2 mm to 3 mm). Mandibular sagittal changes were similar, while vertical changes were better controlled with BAMP. The sagittal intermaxillary relationships improved 2.5 mm more in the BAMP patients. Additional favorable outcomes of BAMP treatment were the lack of clockwise rotation of the mandible as well as a lack of retroclination of the lower incisors. CONCLUSIONS The hypothesis is rejected. The BAMP protocol produced significantly larger maxillary advancement than the RME/FM therapy.