Comprehensive Orthodontic Treatment for Scissor Bite: What You Need to Know

Correcting Scissor Bite in Orthodontics: A Comprehensive Guide for Medical Students and Doctors


A scissor bite is one of the more complex and less common types of malocclusion in orthodontics. Although not as frequently encountered as overbites, crossbites, or underbites, a scissor bite presents unique challenges that require specialized diagnosis and treatment. Correcting this malocclusion can prevent long-term dental problems, improve oral function, and enhance aesthetics. This article aims to provide an in-depth look into the causes, diagnosis, and treatment options for scissor bite correction, making it an essential read for medical students and doctors alike.

What is a Scissor Bite?

A scissor bite occurs when the upper teeth overlap the lower teeth either entirely or partially, without proper contact between them. It’s characterized by an abnormal occlusion, where the upper jaw’s teeth occlude on the buccal side of the lower jaw’s teeth, resembling the motion of scissors. The scissor bite can affect either one side (unilateral) or both sides (bilateral) of the mouth.

Unlike other types of malocclusion, such as crossbites or underbites, a scissor bite often results from skeletal discrepancies between the upper and lower jaws, making it harder to treat.

Types of Scissor Bite

There are two primary types of scissor bite:

1. Unilateral Scissor Bite: In this case, the scissor bite occurs on only one side of the mouth. This is more common than bilateral scissor bite and may be associated with asymmetrical jaw growth.

2. Bilateral Scissor Bite: This involves both sides of the mouth, where the upper teeth completely overlap the lower teeth. This type is less common but can lead to more severe complications if left untreated.

Lingual and Buccal Scissor Bite

• Lingual Scissor Bite: This occurs when the lower teeth sit entirely inside the upper teeth. It can be due to a narrow lower arch or a wider upper arch.

• Buccal Scissor Bite: In this variation, the lower teeth are positioned outside the upper teeth, often due to a wide lower dental arch or a narrow upper arch.

Causes of Scissor Bite

Scissor bite can develop due to several factors, including genetics, environmental influences, or a combination of both. The following are some of the most common causes of scissor bite:

1. Genetic Factors
Genetics plays a significant role in the development of scissor bite. If one or both parents have a scissor bite or any other form of malocclusion, the likelihood of their children developing the same condition increases. Genetic predispositions to abnormal jaw growth or tooth eruption patterns can contribute to the development of a scissor bite.

2. Jaw Size Discrepancy
One of the primary causes of scissor bite is a mismatch between the size of the upper and lower jaws. A wide upper jaw combined with a narrow lower jaw can result in the upper teeth completely overlapping the lower teeth, leading to a scissor bite. This skeletal discrepancy often requires a combination of orthodontic treatment and jaw correction techniques.

3. Abnormal Tooth Eruption
Abnormal eruption of teeth, where the teeth fail to grow into their proper positions, can lead to scissor bite formation. This can happen due to crowding, missing teeth, or improper spacing between the teeth. Early detection and treatment are critical to prevent more severe alignment problems.

4. Childhood Habits
Certain childhood habits, such as thumb sucking or prolonged use of pacifiers, can interfere with the proper growth of the jaws and teeth. This can lead to various types of malocclusion, including scissor bite, as the jaws may develop abnormally due to constant pressure from these habits.

5. Premature Loss of Primary Teeth
The premature loss of baby teeth can result in the permanent teeth erupting in abnormal positions, disrupting the normal occlusion of the teeth. When teeth grow into improper positions, it can contribute to the development of a scissor bite.

6. Cleft Lip and Palate
Children born with cleft lip and palate are more likely to develop dental malocclusions, including scissor bite. This is due to the altered structure of the jaws and teeth caused by the cleft.

Consequences of Untreated Scissor Bite

An untreated scissor bite can lead to significant dental, functional, and aesthetic complications. The earlier the diagnosis and treatment, the better the long-term prognosis. Below are some of the potential consequences of leaving a scissor bite untreated:

1. Excessive Tooth Wear
A scissor bite often causes abnormal wear on the teeth due to improper occlusion. This can lead to the breakdown of the enamel, which increases the risk of tooth sensitivity, cavities, and even tooth loss over time.

2. Difficulty Chewing and Speaking
Scissor bite can interfere with normal chewing and speech patterns. The lack of proper contact between the upper and lower teeth makes it challenging for patients to chew food efficiently. Over time, this can lead to digestive issues. Additionally, speech difficulties, such as a lisp or trouble pronouncing certain sounds, can arise from improper tongue positioning caused by a scissor bite.

3. TMJ Disorders and Jaw Pain
A misaligned bite places extra strain on the temporomandibular joint (TMJ), which can lead to jaw pain, headaches, and TMJ disorders. Patients with scissor bite often experience jaw discomfort due to the abnormal positioning of the teeth and the additional stress placed on the joints.

4. Facial Asymmetry
In more severe cases, a scissor bite can lead to facial asymmetry as the jaws grow in an imbalanced way. This can affect the patient’s facial profile and overall appearance, leading to aesthetic concerns and reduced self-confidence.

5. Periodontal Issues
Improper alignment of the teeth can lead to difficulties in maintaining oral hygiene, which increases the risk of gum disease. The misaligned teeth in a scissor bite can trap food particles and plaque, making it harder to clean the teeth properly. Over time, this can lead to gum recession, inflammation, and other periodontal issues.

Diagnosis of Scissor Bite

Diagnosing a scissor bite requires a comprehensive evaluation by an orthodontist. A detailed diagnosis helps determine the severity of the malocclusion and guides the development of an effective treatment plan. The following are common diagnostic tools and methods used to assess scissor bite:

1. Clinical Examination
The orthodontist begins by examining the patient’s teeth and jaws during a clinical evaluation. The dentist will observe how the upper and lower teeth fit together when the patient closes their mouth, looking for any signs of malocclusion, such as tooth wear, gum recession, or jaw misalignment.

2. Dental Impressions
Dental impressions or digital scans are often taken to create an accurate model of the patient’s bite. These models allow the orthodontist to visualize the alignment of the teeth and plan the most appropriate treatment.

3. X-rays and Cephalometric Analysis
X-rays, including panoramic and cephalometric X-rays, are essential in evaluating the relationship between the teeth, jaws, and surrounding structures. Cephalometric analysis helps determine whether the scissor bite is primarily due to skeletal or dental issues, allowing for more precise treatment planning.

4. 3D Imaging and Digital Models
Advanced 3D imaging technology can be used to create detailed models of the patient’s teeth and jaws, providing a more accurate diagnosis. This is particularly useful for complex cases of scissor bite, where a three-dimensional view of the dental structures is necessary to develop a customized treatment plan.

Treatment Options for Correcting Scissor Bite

Correcting a scissor bite requires a tailored approach based on the severity of the malocclusion, the patient’s age, and whether the scissor bite is caused by dental or skeletal discrepancies. The following are some of the most effective treatment modalities for scissor bite correction:

1. Orthodontic Braces
Braces are a common and effective treatment for scissor bite correction. Braces apply continuous pressure to the teeth, gradually moving them into the correct positions.

• How Braces Correct Scissor Bite: Braces are used to shift the upper teeth inward or the lower teeth outward, depending on the type of scissor bite. The orthodontist may also use elastics or other devices to aid in the movement of the teeth. For cases with severe crowding, additional space may need to be created to allow proper alignment.

2. Palatal Expanders
Palatal expanders are used to correct scissor bites caused by a narrow upper jaw. These orthodontic appliances widen the upper arch by applying gentle pressure on the palate over time, helping to achieve better alignment between the upper and lower teeth.

• Types of Palatal Expanders:

• Fixed Palatal Expanders: These are cemented onto the upper molars and cannot be removed by the patient. They are gradually adjusted by the orthodontist to widen the upper arch.

• Removable Palatal Expanders: These are typically used for milder cases and can be taken out for cleaning and eating.

3. Clear Aligners (Invisalign)
Clear aligners, such as Invisalign, offer a more discreet and comfortable alternative to traditional braces. These custom-made plastic trays fit snugly over the teeth and gradually move them into the correct alignment.

• Benefits of Clear Aligners:

• Clear aligners are nearly invisible, making them a preferred option for adults.

• They are removable, allowing for easier cleaning and eating.

• Clear aligners are custom-fitted, providing more comfort than traditional braces.

4. Orthognathic Surgery
In cases where a scissor bite is caused by significant skeletal discrepancies, orthodontic treatment alone may not be sufficient. Orthognathic surgery may be required to reposition the jaws and correct the underlying skeletal problem.

• What is Orthognathic Surgery? Orthognathic surgery involves cutting and repositioning the upper or lower jaw to correct the misalignment. This procedure is usually performed in conjunction with orthodontic treatment and can provide a long-term solution for severe cases of scissor bite.

5. Tooth Extraction
In some cases, scissor bite correction may require the extraction of one or more teeth, especially if crowding is a contributing factor. Tooth extraction creates space in the dental arch, allowing the remaining teeth to align properly.

• How Tooth Extraction Helps: By removing crowded teeth, the orthodontist can create the necessary space to guide the remaining teeth into their proper positions using braces or clear aligners.

6. Elastics and Temporary Anchorage Devices (TADs)
Elastics, or rubber bands, are often used in combination with braces to provide additional pressure to correct scissor bite. TADs are small titanium screws that serve as anchor points, providing extra stability and control during tooth movement.

• How TADs and Elastics Work: TADs are placed in the jawbone to serve as stable anchors for tooth movement. Elastics apply gentle force to the teeth, helping to move them into their correct positions.

7. Early Orthopedic Treatment
For children and adolescents with developing jaws, early intervention with orthopedic appliances can prevent scissor bite from worsening over time. These appliances modify jaw growth and correct skeletal discrepancies, allowing the jaws to develop more symmetrically.

• Benefits of Early Treatment: Early orthopedic treatment can guide jaw development, preventing more severe malocclusions in adulthood. Early intervention also reduces the need for invasive procedures such as surgery.

Post-Treatment Retention

After correcting a scissor bite, it is essential to maintain the results through the use of retainers. Retainers hold the teeth in their new positions, preventing them from shifting back into their original misaligned state.

Types of Retainers:

• Removable Retainers: These retainers are worn at night and can be removed during the day for eating and cleaning. They are typically used after orthodontic treatment to maintain the alignment of the teeth.

• Fixed Retainers: These consist of a thin wire bonded to the back of the teeth, preventing them from moving out of place. Fixed retainers are particularly useful for patients at high risk of relapse.

Conclusion: The Importance of Correcting Scissor Bite

Correcting a scissor bite is essential for improving both oral function and aesthetics. If left untreated, scissor bite can lead to long-term dental complications, including excessive tooth wear, TMJ disorders, and difficulties with chewing and speech. Early diagnosis and intervention are key to preventing these issues and achieving lasting results.

For medical students and doctors, understanding the complexities of scissor bite correction is crucial for providing comprehensive orthodontic care. With modern advances in orthodontics, including braces, clear aligners, and orthognathic surgery, patients of all ages can benefit from effective scissor bite treatment and enjoy improved oral health and aesthetics.