Third Molar Angulation Research Articles

Patterns of third molar impaction in a group of volunteers in Turkey.

The aim of this study was to investigate the different variables in mesio-vertically positioned impacted or erupted third molars in a group of volunteers in Turkey to determine the angular changes and levels of eruption radiographically using standardised panoramic radiographs. There were 213 volunteers with impacted and erupted third molars included in this study, most of whom were dental students. Standardised panoramic radiographs were taken from all the volunteers. The radiographic parameters included angulation of tooth, level of eruption, development of root, mesiodistal crown width, retromolar space, and gonial angle. Statistical analysis was done using the t-test for independent groups. It was found that the mesiodistal angulation of third molars was significantly greater while the retromolar space of third molars was significantly smaller in the impacted group (P<0.05). There was also a significant difference in retromolar space/third molar crown width ratio (P<0.05).

Influence of orthodontic treatment on development of third molars

We aimed to find out whether extraction of lower premolars and subsequent closure of the space by a fixed appliance influenced the chances of mandibular third molars erupting.We compared angular and linear measurements of lower third molars on dental panoramic tomograms in 30 orthodontic patients with similar measurements from 30 patients with impacted third molars in intact arches.We found that the mesial angulation of lower third molars was reduced from 50° to 43 ° by orthodontic treatment (P< 0.001). Distance to the occlusal plane was reduced from 12mm to 10mm (P< 0.001). The space available increased from 4mm to 11mm (P< 0.001).We conclude that extraction of lower premolars and orthodontic treatment to achieve complete closure of the space allowed the positions of many impacted lower third molars to improve significantly.

A comparison of results of second molar and first premolar extraction treatment

The purpose of this study was to examine treatment results of maxillary and mandibular second molar extraction cases and compare them with treatment results of maxillary and mandibular first-premolar extraction cases. Records of 22 maxillary and mandibular second-molar extraction cases and 22 maxillary and mandibular first-premolar extraction cases were evaluated. For each case, pretreatment and posttreatment lateral cephalograms were traced and several cephalometric parameters were compared. From the pretreatment and posttreatment panoramic radiographs, angulations of the maxillary and mandibular third molars were evaluated. Average treatment time, in months, was recorded for both groups. The data obtained from each group were analyzed for statistical difference. The results showed that the two groups had fewer differences than indicated by advocates of second-molar extractions. Analysis of the cephalometric data demonstrated only a few statistical differences between the groups. The maxillary and mandibular incisors in the premolar group were retracted a significantly greater amount than in the second-molar group. The maxillary and mandibular first molars were protracted a greater amount in the premolar group than in the second-molar group. The lower lips in the premolar group were retracted a greater amount than in the second-molar group. The resulting facial profile after extraction of second-molars appears to be no different from that obtained after extraction of first premolars. The pantographic evaluation of the changes in third-molar angulation were not statistically different. In both groups, the maxillary third molars showed an improvement in third-molar angulation, while the mandibular third-molars showed an undesirable increase in angulation. The average treatment time for both groups was not statistically different.

Age-specific angulation of unerupted human third molar teeth in a cross-sectional sample

For males aged 18 to 21, the angulation of unerupted third molars was unrelated to age. A counterbalancing loss of data resulting from tooth eruption and extraction accounted for this null finding. The value of age-specific angulation in determining whether a tooth will eventually erupt may be limited.

The etiology and prediction of mandibular third molar impaction.

1. Skeletal Class II dental base relationship with a shorter, narrower, more acute angled madible was found in association with impacted third molars, compared with erupted teeth. 2. These differences were found at age 18+ years but were less obvious at age 10 to 11 years. 3. There was a reduced amount of mandibular growth in impacted third molar cases. 4. There was a slight tendency for impacted third molars to be larger than those which erupted. 5. The presence of a space between second and third molars in the early stages of development is not an indication that the third molar will erupt. 6. The developmental angulation of the third molar to the mandibular plane was higher in the impacted third molar group. 7. Accurate prediction of third molar impaction from radiographic measurements is not possible at age 10 to 11 years.