Advancements in Class-I Bimaxillary Protrusion Treatment: En-Masse Distalization with Damon® System and Intraoral Temporary Anchorage Devices: A Case Report

Technical Summary: En-Masse Distalization for Class I Bimaxillary Protrusion Using the Damon System and Extra-Alveolar TADs

Problem Statement
Class I malocclusion with bimaxillary protrusion is characterized by proclined and protrusive maxillary and mandibular incisors accompanied by a convex soft-tissue profile. The conventional management for this condition involves the extraction of all four first premolars followed by anterior retraction. However, this approach carries risks of invasiveness, prolonged treatment time, and potential over-retraction that may flatten an otherwise acceptable facial profile. The authors identify a clinical need for a non-extraction alternative that can effectively manage borderline cases with good soft-tissue profiles while minimizing structural compromise and treatment duration.

Methodology
The paper presents a case report of a 25-year-old male patient diagnosed with Angle's Class I molar relationship on a skeletal Class II base, exhibiting bimaxillary dentoalveolar protrusion, a hypodivergent growth pattern, and a convex soft-tissue profile. The treatment protocol utilized a non-extraction approach combining the Damon® passive self-ligating bracket system with intraoral Temporary Anchorage Devices (TADs).

• Appliance System: Passive self-ligating brackets were bonded, featuring low-torque prescriptions for the maxillary anterior segment to address proclination and standard-torque brackets for the mandibular anterior segment to ensure root stability within the cancellous bone.
• Anchorage Strategy: To achieve en-masse distalization of both arches, extra-alveolar TADs were placed. Specifically, 12 mm stainless steel buccal shelf screws (BSS) were inserted between the mandibular first and second molars, and extended-collar stainless steel infrazygomatic crest (IZC) screws were placed between the maxillary first and second molars.
• Biomechanics: Following leveling and alignment with Copper-Nickel-Titanium (CuNiTi) archwires, 0.019 × 0.025" stainless steel archwires were engaged. A force of 250 g per side was applied, connecting the contralateral screws to facilitate simultaneous backward movement of the entire dental arches.
• Timeline: Active treatment lasted 18 months, with the en-masse distalization phase specifically requiring 8 months.

Key Results
The treatment successfully achieved the intended dentoskeletal and soft-tissue outcomes without tooth extraction or adverse events.

• Dentoskeletal Changes: Post-treatment cephalometric analysis revealed a 5 mm retraction of the lower incisors and a distalization of the upper molars by approximately 5 mm at the crown and 4 mm at the root level. The molars and canines were brought into a Class I relationship with optimal overjet and overbite.
• Soft-Tissue Improvements: The upper lip retracted by 2 mm and the lower lip by 3 mm, bringing the profile within the normal range of the E-line. The convex profile was corrected, resulting in harmonious nasolabial and lip-chin angles.
• Safety and Stability: All four bone screws remained stable throughout the treatment with no loosening, peri-implant inflammation, root contact, or detectable root resorption. The patient reported high satisfaction with the aesthetic outcome and the comfort of the appliances.

Significance and Claims
The paper claims that the combination of the Damon System and extra-alveolar TADs (specifically BSS and IZC screws) creates a low-resistance environment conducive to efficient en-masse distalization. The authors argue that this approach is superior to premolar extraction or simple incisor retraction for borderline bimaxillary protrusion cases where the soft-tissue profile is already acceptable. By avoiding extraction, the treatment preserves healthy tooth structure and mitigates the risk of flattening the facial profile.

The study positions itself as a descriptive case report demonstrating the clinical feasibility of simultaneous maxillary and mandibular distalization without patient-dependent extraoral anchorage. The authors acknowledge limitations, noting that as a single case report, the findings are not generalizable, and the assessment relied on two-dimensional imaging rather than 3D CBCT. Furthermore, long-term stability data is not yet available. However, the case supports the growing body of literature suggesting that extra-alveolar skeletal anchorage can effectively correct protrusion while maintaining facial aesthetics.