Author Information :

Dr.Kartik Samaria

Pages : 28

Issue Details :

December 2025-Issue-1

Acknowledgements :

INTRODUCTION

In orthodontics, the management of third molars, commonly known as wisdom teeth, demands careful and individualized assessment due to the inherent clinical, anatomical, and developmental complexities associated with their eruption.¹ These molars are the final teeth to emerge in the oral cavity, typically erupting between the ages of 17 and 25. As such, they are often met with spatial limitations and are prone to complications including impaction, eruption failure, pericoronitis, distal caries on second molars, and crowding of anterior teeth.

The prevalence of impaction is particularly notable, with literature indicating that up to 72% of third molars fail to erupt normally. This is mainly due to insufficient space in the posterior region of the jaws, particularly the mandible, which is further limited by delayed mandibular growth and the gradual forward shifting of posterior teeth over time. Impaction, based upon erruption pattern  may be classified as mesioangular, distoangular, vertical, or horizontal, each carrying distinct implications for adjacent structures and orthodontic stability.²

From an orthodontic perspective, third molars play a controversial yet significant role in post-treatment planning. Their potential contribution to late lower incisor crowding has long been debated. While studies by Kaplan RG (1975)³ and later by Richardsson ME (1989)⁴ suggest that erupting third molars exert mesial pressure on the dental arch, thereby exacerbating relapse tendencies after orthodontic treatment¹⁹, others argue that crowding is multifactorial and cannot solely be attributed to wisdom teeth. Nevertheless, in patients with borderline arch space or prior lower incisor irregularities, prophylactic extraction of third molars is sometimes recommended as a preventive measure.

Moreover, in cases where first premolars or molars are extracted during orthodontic treatment to relieve crowding or correct malocclusion, the presence and positioning of third molars become even more relevant. In such scenarios, the third molars may be guided or allowed to drift forward to occupy the extraction space and functionally replace missing molars. Conversely, if third molars are poorly angulated or have no functional potential, their removal is often integrated into the broader treatment timeline to avoid future complications.

Additionally, orthodontic anchorage strategies may be influenced by third molar development. In cases involving temporary anchorage devices (TADs) or distalization mechanics, third molars can interfere with force application or require removal prior to initiating certain biomechanical protocols.

Therefore, a comprehensive radiographic evaluation is essential for assessing the angulation, root development, follicular space, and proximity to the inferior alveolar nerve. Decisions regarding the retention, extraction, or monitoring of third molars should be made in concert with the overall orthodontic diagnosis, growth assessment, and long-term retention strategy. Optimal utilization of extraction space requires precise biomechanical planning to ensure balanced retraction, effective crowding resolution, and stable esthetic and functional outcomes.⁵

An important consideration that arises in extraction-based treatment planning, especially when combined with surgery, is the potential impact on third molar (wisdom tooth) development and eruption.⁶ Patients frequently inquire whether the removal of premolars will facilitate the eruption of their wisdom teeth. While third molar eruption is influenced by a variety of factors—such as tooth angulation, degree of root development, retromolar space availability, and individual patterns of craniofacial growth—there is some evidence suggesting that premolar extractions can indirectly affect third molar eruption potential.

When first premolars are removed and the anterior teeth are retracted, posterior teeth may undergo mesial drift as part of the space closure process. This mesial movement can theoretically increase the available space in the posterior segments of the jaw, potentially reducing the risk of third molar impaction. Several researchers have proposed that such spatial reconfiguration may facilitate a more favorable eruption trajectory for third molars, especially in the mandible, where impaction rates are typically higher.⁷

However, this relationship is not universally predictable and varies significantly among individuals. Not all patients experience improved third molar eruption following premolar extraction, as genetic factors, jaw morphology, and eruption timing play equally critical roles. Therefore, the decision to extract premolars should be based on the primary orthodontic objectives, and the status of third molars should be monitored separately through longitudinal radiographic assessments to determine the need for intervention.⁸

Research by Kim et al. (2003) and Kruger et al. (1991) reported that patients who underwent premolar extraction exhibited a more upright angulation of their developing third molars and experienced a higher rate of spontaneous eruption compared to non-extraction cases.^9,20 These findings support the theory that space redistribution resulting from extraction therapy may reduce crowding and promote more favorable eruption trajectories for third molars, particularly in the mandibular arch, where impactions are most common.

However, this optimistic view is counterbalanced by other studies that have failed to demonstrate significant differences in third molar eruption patterns between extraction and non-extraction cases. Although mesial shift of posterior teeth occurs during space closure, the actual increase in functional eruption space is often minimal and may not suffice to accommodate third molars. Factors such as late mandibular growth, inadequate posterior bone remodeling, tooth bud angulation, and timing of root development frequently play a more decisive role in determining eruption outcomes.¹⁰ Therefore, relying on extraction-related mesial drift alone to influence third molar eruption is considered unpredictable and inconsistent.

Given this dichotomy in clinical evidence, it is essential that orthodontists adopt an individualized and comprehensive approach to treatment planning. Each case should be assessed on its own merits, considering variables such as¹¹:

• Skeletal growth pattern and timing (especially mandibular growth spurts).
• Available space in the posterior arch.
• Initial angulation and position of third molar tooth buds.
• Root development stage and eruption sequence.
• Patient’s age, overall dental health, and expected compliance.

From a broader clinical standpoint, the development of third molars—particularly the mandibular third molars—is of significant concern due to their high impaction rate and associated pathological risks.¹² Impacted third molars are implicated in a variety of complications, including:

• Pericoronitis (inflammation and infection of the soft tissue surrounding a partially erupted tooth).
• Cyst formation (such as dentigerous cysts arising from the follicle).
• Root resorption of adjacent second molars.
• Crowding or relapse post-orthodontic treatment.
• In rare cases, even mandibular fractures due to compromised bone integrity in the region.

As such, a thorough understanding of the factors influencing third molar development is essential in formulating orthodontic treatment plans that not only address current malocclusions but also anticipate and minimize future complications. While premolar extractions remain a valuable and sometimes necessary tool in the orthodontist’s armamentarium, their impact on third molar outcomes must be considered within a larger context of craniofacial growth, tooth eruption biology, and patient-specific anatomy.¹⁴

In conclusion, while some evidence supports the notion that premolar extractions may improve the chances of third molar eruption through space creation and mesial drift, this is not universally observed. Therefore, treatment decisions should be case-specific, grounded in current evidence, and guided by long-term clinical judgment to ensure optimal functional and esthetic outcomes.

One of the most enduring and contentious discussions in orthodontics involves the potential role of third molars in contributing to post-treatment mandibular incisor crowding, often referred to as late lower incisor relapse. The notion that erupting third molars exert an anteriorly directed pressure on the dental arch—leading to mesial displacement of the mandibular dentition—has been proposed for decades.¹⁵ This concept suggests that as third molars develop and attempt to erupt into limited space, they create a pushing force on the posterior teeth, ultimately resulting in crowding of the incisors. However, this hypothesis has been increasingly scrutinized in recent literature.

Seminal studies, such as those by Lindqvist and Thilander (1982) and later by Harradine and Pearson (1998), have challenged the idea of a direct causal link between third molars and incisor crowding¹⁶. These researchers observed that patients who had third molars removed exhibited no consistent advantage in maintaining lower incisor alignment compared to those who retained them. Instead, they emphasized residual mandibular growth and physiological mesial drift as more likely contributors to relapse. In particular, the forward and rotational changes in mandibular growth during late adolescence and early adulthood appear to play a substantial role in modifying arch dimensions and incisor position, independent of third molar eruption.

While the relationship between third molars and incisor relapse continues to be clarified, another area of orthodontic interest—though far less studied—is the impact of premolar extractions on third molar development and eruption. Theoretically, extracting first premolars can create space within the dental arch, potentially allowing for mesial drift of molars and reducing the risk of third molar impaction. This has led some clinicians to hypothesize that such extractions could favorably influence third molar angulation, eruption timing, and overall eruption success.

Despite the logical appeal of this theory, the clinical evidence remains limited and inconclusive. While certain studies suggest improved third molar positioning in post-extraction cases, many others fail to demonstrate statistically significant differences in third molar outcomes between extraction and non-extraction groups. Part of the challenge lies in the heterogeneity of study designs, variability in timing of extractions, and differences in growth patterns and anatomical dimensions across populations.

Moreover, most available studies have short follow-up periods or are retrospective in nature, limiting their capacity to provide definitive conclusions. As such, there is a pressing need for well-designed, prospective longitudinal studies that systematically examine:

• Changes in eruption angles and impaction rates post-extraction.
• Effects on eruption timing and root development.
• Influence on mandibular growth direction and dental arch length.
• Correlation with long-term orthodontic stability and retention outcomes.

If future studies confirm that premolar extractions reliably enhance third molar eruption, this finding could greatly impact orthodontic treatment strategies, shaping extraction guidelines and clinical decisions. More importantly, it would provide practitioners with evidence-based guidance on balancing immediate orthodontic needs with long-term eruption considerations.

Given the inherent unpredictability of third molar development—particularly during the adolescent growth period—orthodontists must incorporate long-term considerations into the early stages of treatment planning. Third molars are the last teeth to form and erupt, and their developmental course is highly variable, influenced by factors such as jaw growth, available arch space, and angulation changes during adolescence.¹⁷ Without proactive assessment, these teeth may later contribute to complications including impaction, pericoronitis, root resorption of adjacent second molars, or relapse in tooth alignment, particularly in the mandibular anterior region.

Early intervention guided by diagnostic tools such as panoramic and cephalometric radiographs can provide critical insight into the developing third molars’ positioning, root formation, and spatial relationships within the jaw. These imaging techniques help detect potential eruption challenges at a stage when preventive measures can still be employed effectively. If ignored, the third molars may exert unanticipated pressure or cause disruption to the alignment achieved through orthodontic therapy, thereby compromising treatment stability and long-term results.¹⁸

To mitigate these risks, a comprehensive orthodontic approach must include regular radiographic monitoring throughout treatment, as well as an individualized assessment of the patient’s dental and skeletal maturation. Evaluating growth trends allows clinicians to predict space availability more accurately and make informed decisions about interventions such as premolar extractions, space management, or timing of third molar removal. Moreover, the use of evidence-based prediction models can enhance the orthodontist’s ability to foresee third molar behavior, thereby reducing uncertainty in treatment outcomes.

By thoughtfully integrating third molar assessment into the diagnostic and treatment phases—rather than postponing evaluation until complications arise—clinicians can optimize treatment stability, reduce the likelihood of post-treatment crowding or impaction, and ultimately improve overall patient outcomes. This anticipatory approach reflects a shift in orthodontics toward more predictive, individualized, and growth-sensitive treatment planning, ensuring that third molars are not an afterthought, but a central consideration in the pursuit of long-term success.

 

 

 

 

 

 

 

AIM OF THE STUDY

The study aims to evaluate the angular change of the mandibular third molar after first premolar extraction in bimaxillary protrusion cases in orthodontically treated cases.

 

OBJECTIVES OF THE STUDY

1.     To determine the pre-treatment and post-treatment angular changes of mandibular third molars in bimaxillary protrusion cases treated with first premolar extractions.

2.     To compare the angular changes of mandibular third molars between extraction and non-extraction orthodontic treatment groups.

3.     To analyze the clinical implications of third molar angulation changes on post-treatment stability and the need for subsequent third molar extractions.

 

NULL HYPOTHESIS

There is no significant difference in the angular change of the mandibular third molar after first premolar extraction in bimaxillary protrusion cases in orthodontically treated cases.

 

 

Material and Criteria :

This is a retrospective study,designed to evaluate the angular change of the mandibular third molar after first premolar extraction in bimaxillary protrusion cases in orthodontically treated cases.

Source of Data :

The study was conducted in the Department of Orthodontics and Dentofacial orthopedics, Inderprastha Dental college and Hospital, Sahibabad, Ghaziabad.. The cephalometric radiographs were taken from the Department of Orthodontics and Dentofacial Orthopaedics, Inderprastha Dental college and Hospital. The consent process adhered to ethical standards and patients voluntarily agreed to the use of their diagnostic records for academic and scientific analysis.

Armamentarium :

•                 Cephalostat CS 8000C (Carestream Health, Inc, France) (Figure 1).

•                 Tracing paper measuring 8X10-inch and 0.003-inch in thickness. (Figure 2)

•                 Tracing essentials (lead pencil, 0.5mm lead, eraser, magic tape, divider, protractor, compass, set square, ruler). (Figure 3)

•                 Lateral Cephalograms of patients

•                 X-Ray viewer. (Figure 4)

 

Methods of collecting data

Inclusion criteria :

·       Lateral Cephalogram of patients with age group of 18-35 years

·       Lateral Cephalogram of patient with a full complement of permanent dentition

·       Lateral Cephalogram of patients who underwent fixed Conventional Orthodontic treatment using the MBT system that includes the extraction of all four first premolars.

·       Third molar should be fully erupted.

Exclusion criteria :

·       Lateral cephalograms of patients with missing teeth

·       Patients who have no radiographic identification of the apices of the third molar

·       Lateral cephalograms of patients with impacted third molar

METHOD

A sample of  34 lateral cephalogram of patients who underwent  fixed orthodontic treatment were selected. These lateral cephalograms were divided into two sub-groups: Group A- consisting of 17 patients who underwent orthodontic treatment that included premolar extractions, and Group B- another group of 17 patients who had treatment without  premolar extractions.

Group A	17 patients who had orthodontic treatment that included premolar extractions.
Group B	17 patients who underwent orthodontic treatment without premolar extractions.

 

Lateral cephalograms were taken at Inderprastha Dental College And Hospital. For the purpose of lateral cephalogram, it was taken on CS 8000C (Carestream Health, Inc, France) with exposure 90kV, 15mA for 0.500 seconds with the image receptor at 1.5m was used to capture images keeping Frankfort Horizontal Plane parallel to the floor and midsagittal plane perpendicular to the floor with bilateral ear rods gently inserted into the external auditory meatus to stabilize the head position during exposure. NHP ensures that all patients’ head orientation is recorded in a reproducible and consistent manner, reducing variability in cephalometric analysis.

                        

 Table 1: List of Landmarks for Lateral cephalogram analysis

LANDMARKS	DESCRIPTION
M3	The long axis of the lower third molar
M2	The long axis of the lower second molar
SN PLANE	the sella (S) point, located in the center of the sella turcica (a depression in the sphenoid bone), and the nasion (N), the most anterior point of the nasofrontal suture.
MP PLANE	Tangent to the lower border of mandible
OP PLANE	Line bisecting the overlapping cusps of first molars and incisal edges

The pretreatment and posttreatment were considered as T1 and T2 respectively. They were assessed using a technique that involved tracing the images of the teeth onto matte acetate paper. With a fine felt-tipped black pen, 3 (+) marks on the radiograph,two within the cranium and one over the area of the cervical vertebrae were drawn. The following angular measurements were then taken(Figure 5)-

·       The angle between long axis of the M3 and SN plane

·       The anterior angle between the long axis of M3 and OP

·       The anterior angle formed between the long axis of the M3 and M2

·       the angle between the long axis of M3 and MP

The data was collected in the computer application and then transferred to Microsoft excel for further analysis to compare the Group A and Group B.

Statistical analysis :

Descriptive and inferential statistical analyses were carried out in the present study. Results on continuous measurements were presented as mean±SD.The level of significance was fixed at P = 0.05, and any value ≤.0.05 was considered statistically significant.Paired t test was used to find the significance of study parameters between pre and post treatment group. The statistical software IBM SPSS statistics 22.0 (IBM Corporation, Armonk, NY, USA) was used for the analyses of the data.

 

           SHAPE  \* MERGEFORMAT

Figure 1: Cs 8000c (Carestream Health, Inc, France)

                                SHAPE  \* MERGEFORMAT

Figure 2: Tracing Paper

 SHAPE  \* MERGEFORMAT

Figure 3: Tracing Essentials

                                        

---