The extraction-nonextraction dilemma as it relates to TMD

Pretreatment dentoskeletal comparison between individuals treated with extractions in the 1970s and in the new millennium

OBJECTIVE

This retrospective study aimed to compare the occlusal and dentoskeletal initial features of patients treated with four first premolar extractions in the 1970s and after 2000.

MATERIALS AND METHODS

Group 70' was composed by 30 subjects with Class I malocclusion (mean age of 12.8 years, 10 male, 20 female) treated in the 1970s with four first premolar extractions and comprehensive orthodontic treatment. Group NM comprised 30 subjects with Class I malocclusion (mean age of 13.4 years, 13 male, 17 female) treated in the new millennium, similarly to Group 70'. Initial dental models and lateral cephalograms were digitized and measured using OrthoAnalyzerTM 3D software and Dolphin Imaging 11.0 software, respectively. Initial occlusal and dentoskeletal features were analyzed and compared. Intergroup comparison was performed using t tests (p < 0.05). Holm-Bonferroni correction for multiple comparison was applied.

RESULTS

Group NM showed significantly greater maxillary and mandibular effective lengths and greater maxillary and mandibular incisor protrusion in comparison with Group 70'. Group NM presented a significantly greater lower anterior facial height. Group NM also showed significantly smaller nasolabial angle and protruded inferior lip.

CONCLUSION

Patients with Class I malocclusion treated with four first premolar extractions in the new millennium present a greater degree of dental and labial protrusion, increased lower anterior facial height, and more acute nasolabial angle compared with patients treated similarly in the 1970s. Greater dental and labial protrusion determines first premolar extractions in the new millennium.

CLINICAL RELEVANCE

Despite the decrease of tooth extraction frequency, four first premolar extractions may be justified in cases with severe dental and skeletal protrusions.

Mesiodistal angulation of posterior teeth in orthodontic patients with different facial growth patterns

Background. Mesiodistal and buccolingual angulations of teeth are variable in different malocclusion classes. This study aimed to assess the mesiodistal angulation of posterior teeth in orthodontic patients with vertical, normal, and horizontal facial growth patterns. Methods. This descriptive, cross-sectional study evaluated 150 lateral cephalograms of orthodontic patients. According to cephalometric analysis, facial growth patterns were divided into three groups of normal, horizontal, and vertical (n=50). The angulation of maxillary and mandibular posterior teeth was then measured. Data were analyzed using SPSS 22. Results. The results showed an increase in the mean angle of maxillary and mandibular posterior teeth relative to palatal and mandibular planes in patients with a vertical facial growth pattern. Conversely, their angulation decreased relative to the bisected occlusal plane (BOP). The angulation of posterior teeth decreased relative to palatal and mandibular planes and increased relative to the occlusal plane with an increase in overbite. The mean angle of all maxillary teeth relative to the palatal plane was significantly greater in open bite patients compared to normal and deep bite patients. This value in patients with normal bite was significantly greater than that in deep bite patients (P<0.05). Conclusion. The current results revealed that in patients with a vertical growth pattern, all the posterior teeth had a forward inclination. Conversely, in patients with a horizontal growth pattern, the teeth had a backward inclination.

Short-term effects of systematic premolar extraction on lip profile, vertical dimension and cephalometric parameters in borderline patients for extraction therapy--a retrospective cohort study

OBJECTIVES

The belief of many orthodontists that premolar extraction therapy leads to a loss of vertical dimension and an aggravated facial profile often predetermines a non-extraction approach. We investigated the short-term effects of systematic premolar extraction in borderline cases for extraction therapy on dentofacial parameters, especially vertical dimension and facial profile.

MATERIALS AND METHODS

Of 50 juvenile borderline cases for extraction treatment with a distinct sagittal overjet of 6-9 mm and dental crowding of >6 mm, 25 had all first premolars extracted, whereas the 25 control patients received non-extraction orthodontic treatment with corresponding fixed and removable appliances. Patient selection by multivariate cluster analysis ensured homogeneity at baseline regarding dentoskeletal parameters. Parameter changes were determined with radiographic cephalograms and compared between the extraction and non-extraction group.

RESULTS

The systematic extraction of premolars in borderline patients with a distinct sagittal overjet and crowding did not significantly influence sagittal or vertical skeletal dimension, while leading to a slightly more concave lip profile due to incisor retraction compared to the non-extraction control group.

CONCLUSIONS

The influence of premolar extractions on facial profile is often overestimated, since only slight changes in lip profile are to be expected. In integrated treatment planning, the extraction decision should not be primarily based on concerns about the aggravation of facial profile and loss of vertical dimension.

CLINICIAL RELEVANCE

The decision, whether to extract healthy premolars in borderline patients for extraction therapy, is difficult to make. Our study clarifies the repercussions on cephalometric dentofacial parameters, facilitating future orthodontic extraction decisions.

Frequency evaluation of different extraction protocols in orthodontic treatment during 35 years

BACKGROUND

Studies that show frequencies of different orthodontic treatment protocols can be used as valuable parameters in the interpretation of treatment tendency with time. The purpose of this retrospective study was to evaluate all orthodontic treatment planning conducted at the Orthodontic Department at Bauru Dental School, University of São Paulo, Brazil, since 1973, in order to investigate extraction and non-extraction protocol frequencies selected at each considered period.

METHODS

The sample comprised 3,413 records of treated patients and was evaluated according to the protocol choice, divided into 10 groups: Protocol 0 (non-extraction); Protocol 1 (four first premolar extractions); Protocol 2 (two first maxillary and two second mandibular premolars); Protocol 3 (two maxillary premolar extractions); Protocol 4 (four second premolars); Protocol 5 (asymmetric premolar extractions); Protocol 6 (incisor or canine extractions); Protocol 7 (first or second molar extractions); Protocol 8 (atypical extractions) and Protocol 9 (agenesis and previously missing permanent teeth). These protocols were evaluated in seven 5-year intervals: Interval 1 (1973 to 1977); Interval 2 (1978 to 1982); Interval 3 (1983 to 1987); Interval 4 (1988 to 1992); Interval 5 (1993 to 1997); Interval 6 (1998 to 2002); Interval 7 (2003 to 2007). The frequency of each protocol was compared between the seven intervals, using the proportion test (P < 0.05).

RESULTS

The results showed that 10 protocol frequencies were significantly different among the 7 time intervals.

CONCLUSIONS

The non-extraction protocol frequency increased gradually with consequent reduction of extraction treatments. The four premolar extraction protocol frequency decreased gradually while the two maxillary premolar extraction protocol has maintained the same frequency of indications throughout time.