Completely impacted teeth in dentate and edentulous jaws

The Impact of Genetics and Environmental Factors on the Position of the Upper Third Molars

PURPOSE

The purpose of this study was to estimate the importance of heredity in the position of the upper third molars.

MATERIALS AND METHODS

Panoramic radiographs and lateral cephalograms of same-gender twins were analyzed. The determination of zygosity was performed by means of DNA tests with polymerase chain reaction for the amplification of short tandem repeats and 15 specific DNA markers. Data were estimated by the relative influence of additive genetic factors (A), nonadditive genetic factors (D), the common or shared environment (C), and unique environmental factors (E).

RESULTS

The study sample consisted of 212 twins: 80 dizygotic and 132 monozygotic twins. The genetic analysis showed that the best-fitting model for the size of the molars and their angulations was AE (additive genetic factors and unique environmental factors), in which the additive genetic factors had up to 84% influence and specific environment had up to 40%. Therefore, the ACE (additive genetic factors, common or shared environment, and unique environmental factors) model showed higher significance for the tooth eruption level. The heritability estimates were up to 59%, specific environment contributed up to 16%, and common environment reached 30%.

CONCLUSIONS

Genetic factors play a key role in the position of the upper third molars.

Evaluation of mental foramen position from panoramic dental radiographs

OBJECTIVE

Evaluate the position of mental foramen by measuring the vertical bone height from digital panoramic radiograph and also the variation of resorption pattern by gender and extraction time frame. Materials and methods/study design: Digital panoramic radiographs of 500 patients were reviewed. The study population was divided into four age groups aged 30 to 70 years as (30-39, 40-49, 50-59 and 60-70 years of age). Radiographic Position of mental foramen was evaluated in each panoramic radiograph by measuring the distance from the marginal bone to the mental foramen was being measured. Measurements were taken in each radiograph using Clini-view software. The data collected was subjected to statistical analysis using paired students t-test and chi-square tests.

RESULTS AND CONCLUSION

In our study it was noted that the vertical measurements calculated from the superior margin of mental foramen to the crest of alveolar ridge were greater in edentulous men than in women. This measurement decreased significantly with age. We have noted here that resorption pattern between males and females can be used as an early diagnostic tool and for implant analysis. Studies comparing right and left side edentulous mandibular region are needed for further confirmation.

Management of a transmigrated mandibular canine

The purpose of this article is to report the management of a transmigrated mandibular canine with emphasis on saving the tooth as natural part rather than surgical removal of the transmigrated tooth. There are several treatment options proposed for impacted mandibular canines including surgical removal, exposure and orthodontic alignment, intra-alveolar tooth transplantation (surgical repositioning of a tooth in its alveolar socket) and observation. The technique, surgical repositioning of a tooth involves the surgical extraction of impacted tooth and fixation in the correct position in the dental arch after surgical preparation (correction) of the alveolar socket. It is especially valuable in cases of difficult-to-treat impaction. A repositioned tooth is better substitute than fixed or removable prostheses, and the technique is more cost effective than other methods. Patients with excellent oral hygiene should be considered as preferred candidates for surgical repositioning of tooth. Disadvantages include the invasiveness of surgery, the difficulty of projecting long term stability due to chances of root resorption and loss of gingival attachment.

Acute inflammation at a mandibular solitary horizontal incompletely impacted molar

Acute inflammation is frequently seen in the elderly around incompletely impacted molars located apart from molars or premolars. To identify the factors causing acute inflammation in the solitary molars without second molars or without second and first molars, ages of patients and rates of acute inflammation in 75 horizontal incompletely impacted mandibular molars in contact or not in contact with molars in subjects 41 years old or older were studied using orthopantomographs. Acute inflammation was seen in nine third molars out of 48 third molars in contact with second molars (18.8%), whereas acute inflammation was seen in 11 molars out of 19 solitary molars without second molars or without first and second molars (57.9%) (p < 0.01). The mean age of 48 subjects with third molars in contact with the second molar was 50.42 +/- 7.62 years, and the mean age of 19 subjects with isolated molars was 65.16 +/- 10.41 years (p < 0.0001). These indicate that a solitary horizontal incompletely impacted molar leads more frequently to acute inflammation along with aging due to possible bone resorption resulting from teeth loss.

Clinical management of impacted maxillary canines

Ectopic eruption and impaction of canines is a frequently encountered clinical problem. The incidence of impaction ranges between 1% and 3%. The cause of canine impaction can be the result of localized factor(s) or can be a polygenic multifactorial inheritance and associated with other dental anomalies. There are a number of possible sequelae to canine impactions, ranging from loss of space in the arch to resorption of the roots of the neighboring teeth. Although the management of the ectopically erupting teeth necessitates the combined expertise of a number of clinicians, the orthodontist should have the primary responsibility of coordinating these efforts to provide the patient with the optimal treatment options with the most stable and favorable outcome.