MIXED DENTITION SPACE ANALYSIS OF A SOUTHERN ITALIAN POPULATION: NEW REGRESSION EQUATIONS FOR UNERUPTED TEETH

Mixed dentition analysis forms a critical aspect of early orthodontic treatment. In fact an accurate space analysis is one of the important criteria in determining whether the treatment plan may involve serial extraction, guidance of eruption, space maintenance, space regaining or just periodic observation of the patients. The aim of the present study was to calculate linear regression equations in mixed dentition space analysis, measuring 230 dental casts mesiodistal tooth widths, obtained from southern Italian patients (118 females, 112 males, mean age 15±3 years). Student’s t-test or Wilcoxon test for independent and paired samples were used to determine right/left side and male/female differences. On the basis of the sum of the mesiodistal diameters of the 4 mandibular incisors as predictors for the sum of the widths of the canines and premolars in the mandibular mixed dentition, a new linear regression equation was found: y = 0.613x+7.294 (r= 0.701) for both genders in a southern Italian population. To better estimate the size of leeway space, a new regression equation was found to calculate the mesiodistal size of the second premolar using the sum of the four mandibular incisors, canine and first premolar as a predictor. The equation is y = 0.241x+1.224 (r= 0.732). In conclusion, new regression equations were derived for a southern Italian population.

The effect of zinc-carbonate hydroxyapatite versus fluoride on enamel surfaces after interproximal reduction

The aim of this study was to qualitatively investigate the effects of a zinc-carbonate hydroxyapatite (Zn-CHA) containing toothpaste on stripped enamel morphology in a pH cycling model in vitro and to compare the efficacy of this toothpaste versus fluoride one which still represent the gold standard to remineralize early enamel lesions. Twenty-one extracted lower incisors underwent to interproximal enamel reduction with metal strips (Horico 80 µm) on both mesial and distal surfaces. They were then sliced into mesial and distal halves and the 42 samples obtained were randomly assigned to 3 groups of 14 enamel specimens each. For 8 days, teeth were placed in lactic acid solution for 2 h three times a day with 2 h distilled water preservation in between. After each demineralization bath, samples of Group A were brushed with Zn-CHA containing toothpaste while samples of Group B were brushed with 1,400 ppm fluoride dentifrice for 5 min before immersion into water. Group C of untreated samples served as control. All the samples were then prepared for scanning electron microscopy (SEM) analysis. A score rating system was used to perform a non-parametric statistical analysis. No statistically significant differences were found between the samples brushed with fluoride toothpaste and those untreated (Groups B and C) where the highest grade of damage was found, while the lowest grade was recorded in the samples brushed with Zn-CHA (Group A) and there was a statistically significant difference between this group and the other two groups.

Periodontal healing after 'orthodontic extraction' of mandibular third molars: a retrospective cohort study

In this study we investigated periodontal healing of mandibular second molars following 'orthodontic extraction' of adjacent impacted third molars, under the null hypothesis that there would be no difference in probing pocket depths (PPD) and clinical attachment levels (CAL) at the distal aspect of second molars before and after treatment. A retrospective survey was conducted of 64 patients who consecutively underwent 'orthodontic extraction' of mandibular third molars in close anatomical relationship with the mandibular canal from January 1997 to January 2011. Age, smoking habit, and PPD and CAL at the distal aspect of second molars before and after treatment were recorded. A statistically significant difference was found in PPD and CAL before and after treatment for the overall sample and for the sample classified by age (>25 or ≤25 years), smoking habit (smoker or non-smoker), and type of third molar impaction (horizontal, mesioangular, or vertical). Median PPD and CAL reductions amounted to 6mm and 5mm, respectively. The null hypothesis was rejected and orthodontic extraction proved to be indicated for those impacted mandibular third molars at high risk of a postoperative periodontal defect at the distal aspect of the adjacent second molar.

Headache and cranio-mandibular disorders during adolescence

A clinical and epidemiological investigation was performed on 62 adolescents, 21 males and 41 females, with recurring headaches, in order to analyze the connections between the cephalalgia and the signs and symptoms of mandibular dysfunction. The anamnestic and objective data were reviewed with the aid of the Helkimo indices and compared to data on a control group of comparable age who were not headache sufferers. The most statistically significant signs encountered (p < 0.001) were: pain on palpation of masticatory muscles (61%), altered (43%) or reduced (27%) mandibular movement, preauricular tenderness (19%); the high incidence of parafunctions indicated the behavioral substrate. This pilot study reveals a link between the two pathologies and the need for early diagnosis, preventive identification of the subjects at risk and interdisciplinary cooperation.

A retentive system for intra-oral fluoride release during orthodontic treatment

The aim of this study was to test a particular type of intra-oral fluoride releasing device (IFRD), designed to release 0.04 mg/day of fluoride over a period of 6 months, using customized holders, in patients receiving orthodontic treatment. Discomfort, holder detachment, plaque accumulation near the device, and the presence of gingivitis, bleeding, white spot lesions, and/or decay was recorded in 76 orthodontic patients (53 experimental and 23 controls) before and after wearing the device for 12 months. The system proved to be easy and quick to use, and did not cause discomfort. There were no significant differences between the treated and the control groups for plaque index, bleeding, or the presence of gingivitis. In addition, no carious and/or white spot lesions occurred during the duration of this study in the test group.

Management of bilaterally impacted mandibular second and third molars

BACKGROUND

The authors present an interdisciplinary approach to treating bilateral impaction of mandibular second molars.

CASE DESCRIPTION

A 22-year-old man had a bilateral deep horizontal impaction of his mandibular second molars. The mandibular third molars lay above and parallel to the second molars. After an orthodontic assessment, the authors decided to distally upright the third molars, remove them and then orthodontically reposition the second molars if they were not ankylosed. This combined orthodontic-surgical approach was successful.

CLINICAL IMPLICATIONS

This case illustrates the importance of strong cooperation among various specialists to establish the optimal comprehensive treatment plan.

Removing high-risk impacted mandibular third molars: a surgical-orthodontic approach

The authors present a surgical-orthodontic approach to the extraction of impacted mandibular third molars that have a close anatomical relationship between the root and the mandibular canal. They explain that this procedure, in selected cases, decreases the risk of neurological complications and facilitates extraction.

[Molar uprighting: biomechanical considerations]

Various biomechanical systems for the molar uprighting have been described. The Authors analyze the force system delivered on the molar and on the anchorage unit. The biomechanical considerations are emphasized in each single case.