Identification of condylar anatomy affects the evaluation of mandibular growth: guidelines for accurate reporting and research

Systematic review of quality of reporting, outcome measurements and methods to study efficacy of preventive and therapeutic approaches to peri-implant diseases

AIM

To systematically review the literature and to assess the quality of reporting, outcome measurements and methods in both preventive and therapeutic approaches to peri-implant mucositis (PM) and peri-implantitis (PI).

MATERIALS AND METHODS

Randomized (RCT) and Controlled Clinical Trials (CCT), evaluating preventive or therapeutic interventions in patients with PM or PI, were identified through searching in electronic databases and in relevant journals. Reporting and methods were evaluated through an analysis of the risk of biases and quality score. Sub-analysis was performed in four subgroups: prevention of PM and PI, treatment of PM, and non-surgical and surgical treatment of PI.

RESULTS

Thirty-two trials (29 RCT) were identified as accomplishing inclusion criteria after full-text reading. Seven focused on prevention, and among those dealing with therapy, six were related to PM and 19 related to PI therapy (10 non-surgical and 9 surgical). Analysis found that quality of reporting and methods was generally low and surrogate outcomes were often chosen.

CONCLUSIONS

Current literature on PM and PI prevention and treatment does not allow extracting applicable clinical information. Quality of methods and reporting guidelines should be encouraged. In particular, ad hoc guidelines should be designed for peri-implant diseases.

Condylar growth and mandibular positioning with stepwise vs maximum advancement

INTRODUCTION

The aim of this study was to compare the effects of several Class II malocclusion treatments on condylar growth and positioning of the mandible.

METHODS

The material comprised series of lateral cephalograms obtained at the start, after about 6 months, and after about 12 months of treatment from 3 groups of consecutively treated patients who used a headgear-activator with stepwise mandibular advancement (HGA-S), a headgear-activator with maximum jumping of the mandible (HGA-M), and a headgear-Herbst appliance with stepwise advancement (HGH-S), respectively. Six-month growth data from matched controls were used to calculate the net treatment effects.

RESULTS

Mandibular prognathism was enhanced after stepwise advancement but not after maximum jumping, and only during the initial phase of therapy; the effect was significantly greater for the fixed functional appliance than for the removable functional appliance. Lower-facial height was increased by the HGA-S, unchanged by the HGA-M, and restrained by the HGH-S. The low construction bite of the HGH-S meant that the extent of bone apposition on the posterior and superior parts of the condyle was similar, whereas the high construction bite of the HGA-S and the HGA-M meant that the effect on the superior part was greater, but only significantly so after stepwise advancement.

CONCLUSIONS

The mode of jumping, the vertical opening, and whether the functional appliance is fixed or removable affect the amount and pattern of condylar growth, and the position of the mandible.

Does functional appliance treatment truly improve stability of mandibular vertical distraction osteogenesis in hemifacial microsomia?

AIM

After mandibular unilateral distraction osteogenesis (DO) a gradual reappearance of the vertical asymmetry during growth is observed. A pre- and post-surgical functional-orthodontic treatment was added to our distraction protocol in the attempt to increase long-term stability. In order to evaluate the actual efficacy of such a combined treatment, two samples of children affected by hemifacial microsomia were compared long-term.

MATERIAL

Ten children were treated by a combined orthodontic-distraction treatment, seven by distraction only.

METHOD

Only the vertical changes in the mandible and maxilla in the panoramic and postero-anterior cephalometric X-rays were measured.

RESULTS

All of the patients showed a gradual return of the asymmetry with growth. Occlusal plane correction and, to a much lesser extent, mandibular vertical ramus height correction were better maintained over 5 years post-DO in the orthopaedic group.

CONCLUSION

Although orthopaedic treatment allows for a more stable occlusal plane and for a slower return of the mandibular vertical asymmetry, it has mainly a dento-alveolar effect. Therefore, the decision of applying an orthopaedic treatment associated with distraction, should be taken by surgeon and orthodontist together, considering both the advantages and the disadvantages of this treatment.

Masseter muscle thickness and mechanical advantage in relation to vertical craniofacial morphology in children

OBJECTIVE

To investigate the relationship between vertical craniofacial morphology and masseter muscle thickness and mechanical advantage in children.

MATERIAL AND METHODS

The sample comprised 72 children (36 F, 36 M), 8.5-9.5 years of age, with various malocclusions and no previous orthodontic treatment. The thickness of the masseter was measured bilaterally by means of ultrasonography, and the recordings were performed both in relaxation and under contraction. Mechanical advantage was measured on the lateral cephalograms as the ratio between the masseter moment and the bite force moment arms. Two linear ratios and three angular measurements were used to describe vertical craniofacial morphology.

RESULTS

The mean masseter thickness was greater in the male group (p<0.05) in both relaxed and contracted conditions. There were no significant sex differences for the mechanical advantage or for the measurements of vertical craniofacial morphology. In females, there is a positive association between masseter muscle thickness and its mechanical advantage. Multiple regression analysis showed a positive association between posterior to anterior facial height ratio in both genders and a negative association between masseter thickness and the intermaxillary angle in females.

CONCLUSIONS

There is a significant association between posterior to anterior facial height and the masseter muscle in children. The importance of the masseter muscle is more evident in the vertical facial morphology of females.

Evaluation of Class II treatment by cephalometric regional superpositions versus conventional measurements

INTRODUCTION

The aims of this study were (1) to evaluate cephalometric changes in subjects with Class II Division 1 malocclusion who were treated with headgear (HG) or Fränkel function regulator (FR) and (2) to compare findings from regional superpositions of cephalometric structures with those from conventional cephalometric measurements.

METHODS

Cephalographs were taken at baseline, after 1 year, and after 2 years of 65 children enrolled in a prospective randomized clinical trial. The spatial location of the landmarks derived from regional superpositions was evaluated in a coordinate system oriented on natural head position. The superpositions included the best anatomic fit of the anterior cranial base, maxillary base, and mandibular structures.

RESULTS

Both the HG and the FR were effective in correcting the distoclusion, and they generated enhanced differential growth between the jaws. Differences between cranial and maxillary superpositions regarding mandibular displacement (Point B, pogonion, gnathion, menton) were noted: the HG had a more horizontal vector on maxillary superposition that was also greater (.0001 < P < .05) than the horizontal displacement observed with the FR. This discrepancy appeared to be related to (1) the clockwise (backward) rotation of the palatal and mandibular planes observed with the HG; the palatal plane's rotation, which was transferred through the occlusion to the mandibular plane, was factored out on maxillary superposition; and (2) the interaction between the inclination of the maxillary incisors and the forward movement of the mandible during growth.

CONCLUSIONS

Findings from superpositions agreed with conventional angular and linear measurements regarding the basic conclusions for the primary effects of HG and FR. However, the results suggest that inferences of mandibular displacement are more reliable from maxillary than cranial superposition when evaluating occlusal changes during treatment.

Three-dimensional assessment of the reliability of a postural face-bow transfer

STATEMENT OF PROBLEM

Incorrect 3-dimensional orientation of a dental cast may compromise the functional and esthetic result of prosthetic restorations.

PURPOSE

This study assessed the reliability of a new method to transfer the 3-dimensional orientation of the occlusal plane with a postural face-bow.

MATERIAL AND METHODS

The 3-dimensional position of the occlusal plane in 20 subjects (age 20 to 32 years) with a complete dentition in both arches was assessed with a postural face-bow. An irreversible hydrocolloid impression of the maxillary arch was made for each subject and poured in dental stone. The maxillary arch was mounted in an articulator with use of a postural face-bow. The 3-dimensional position of the occlusal plane was then measured and compared to the values obtained with the use of a previously certified, computerized, noninvasive instrument. This instrument digitizes the coordinates of dental and facial landmarks and then calculates the spatial position of the occlusal plane. For each subject, the direct assessment and the face-bow measurement were compared by calculating the absolute difference of the following: the inclination of the occlusal plane relative to the true vertical, frontal plane projection (angle alpha) and sagittal plane projection (angle beta); intercondylar distance; distance of the center of gravity of the anterior part of the maxillary arch to the midpoint of the intercondylar axis; and the maxillary right canine to right condylion distance. Descriptive statistics of the differences were calculated.

RESULTS

The postural face-bow appeared reliable and compared well to the computerized assessment, with mean differences ranging from 2.5 degrees to 3 degrees.

CONCLUSION

In the population tested, a postural face-bow reliably reproduced the spatial orientation of the occlusal plane relative to the true horizontal plane. This position was transferred to an articulator with limited errors.

Headgear versus function regulator in the early treatment of Class II, division 1 malocclusion: a randomized clinical trial

A prospective randomized clinical trial was conducted to evaluate the early treatment of Class II, Division 1 malocclusion in prepubertal children. Facial and occlusal changes after treatment with either a headgear or a Fränkel function regulator are reported. Molar and canine relationships, overjet, intermolar and intercanine distances were measured from casts taken every 2 months, and mounted on a SAM II articulator. Cephalometric radiographs were taken annually. The results indicate that both the headgear and function regulator were effective in correcting the malocclusion. A common mode of action of these appliances is the possibility to generate differential growth between the jaws. The extent and nature of this effect, as well as other skeletal and occlusal responses differ. Treatment in late childhood was as effective as that in midchildhood. This finding suggests that timing of treatment in developing malocclusions may be optimal in the late mixed dentition, thus avoiding a retention phase before a later stage of orthodontic treatment with fixed appliances. However, a number of conditions may dictate an earlier intervention in the individual patient.