Relapse After Orthognathic Surgery Causes and Revision Options

What Is Jaw Surgery Relapse and the Anatomy Involved?

Orthognathic surgery repositions the facial skeleton to correct severe dentofacial deformities, malocclusion, and airway compromise. Jaw surgery relapse refers to the partial or complete return of the jawbones or teeth towards their original pre-operative positions following corrective surgery. Relapse can be broadly categorised into skeletal relapse, where the basal bone segments shift at the osteotomy sites (the surgical bone cuts), and dental relapse, where the teeth drift within the alveolar bone despite the jaws remaining stable. Understanding the distinction is fundamental for determining whether a patient requires orthodontic adjustment or secondary surgical intervention.

The anatomical framework involved in jaw stability comprises the maxilla (upper jaw), the mandible (lower jaw), the temporomandibular joints (TMJs), the masticatory muscles, and the surrounding soft-tissue envelope. During a Le Fort I maxillary osteotomy or a bilateral sagittal split osteotomy (BSSO) of the mandible, rigid internal fixation using titanium miniplates and monocortical or bicortical screws secures the mobilised bone segments. The stability of this construct relies on bone healing across the osteotomy gaps, the positional integrity of the mandibular condyles within the glenoid fossae, and the physiological adaptation of the suprahyoid and masticatory musculature.

Relapse can manifest early during the initial healing phase (within the first six to eight weeks) or late (months to years post-operatively). Early instability typically relates to fixation failure, improper seating of the condyles during surgery, or acute muscular tension. Late relapse is more frequently driven by biological remodeling, continuous mandibular growth in younger individuals, progressive or idiopathic condylar resorption, or inadequate post-surgical orthodontic retention. Distinguishing between these mechanisms requires a rigorous clinical and radiographic assessment.

Causes and Risk Factors for Post-Surgical Relapse

The aetiology of jaw surgery relapse is multifactorial, involving mechanical, biological, anatomical, and patient-specific elements. One primary driver is soft-tissue and muscular tension. When the jaws are advanced or lengthened significantly, the surrounding soft tissues, facial skin, and muscles—particularly the masseter, medial pterygoid, and suprahyoid muscle groups—exert continuous counter-traction against the osteotomy sites. In large mandibular advancements (frequently exceeding seven to eight millimetres) or substantial counter-clockwise rotations of the occlusal plane, these reciprocal forces can overpower the initial fixation or induce creeping skeletal remodeling over time.

A critical biological cause of severe late mandibular relapse is idiopathic condylar resorption (ICR), also termed progressive condylar resorption. This condition involves the progressive breakdown and volume loss of the mandibular condylar head, predominantly affecting adolescent and young adult females with a pre-existing high mandibular plane angle. As the condyle loses height, the posterior mandibular ramus shortens, causing the lower jaw to rotate downwards and backwards, which re-establishes a retrognathic profile and an anterior open bite. Other biological factors include uncontrolled juvenile idiopathic arthritis, systemic connective tissue disorders, and vascular compromise to bone segments.

Lifestyle and environmental factors can also impair skeletal stability. Chronic sleep-disordered breathing, persistent mouth breathing, atypical tongue-thrust swallowing patterns, and bruxism (teeth grinding) apply directional forces that jeopardise the occlusion. In specific geographic contexts, such as South Asia, intense bilateral or unilateral masticatory stress associated with chewing areca nut (supari), paan, or gutka places heavy cyclical loads on healing osteotomies, which can destabilise fixation hardware or aggravate temporomandibular joint deterioration.

Symptoms and Clinical Presentation

The presentation of orthognathic relapse varies depending on the specific surgical movements originally executed and the underlying mechanism of instability. The most immediate sign noticed by patients is an occlusal discrepancy: the teeth no longer interlock as they did immediately after surgery. Patients frequently report that their bite feels 'off' or that only their back molars make contact while their front teeth stay open, indicating the redevelopment of an anterior open bite. In cases of mandibular setback relapse, the lower front teeth may once again project forward into a Class III edge-to-edge or underbite position.

Aesthetic changes accompany occlusal shifts. Patients may notice the gradual retrusion of the chin, a loss of jawline definition, or the recurrence of facial asymmetry where the chin point deviates back towards its pre-operative side. Changes in the resting posture of the lips, such as worsening lip incompetence (inability to close the lips comfortably without straining the mentalis muscle), can also emerge. When relapse compromises the pharyngeal airway volume—often seen after bimaxillary or mandibular retrusion—patients may report the onset or worsening of snoring, unrefreshing sleep, and obstructive sleep apnoea symptoms.

Temporomandibular joint symptoms frequently co-occur with skeletal relapse. Patients may experience new or worsening joint sounds, such as clicking, popping, or crepitus (a grinding, crunching sensation), coupled with pre-auricular pain and restricted mouth opening. In cases involving condylar resorption, progressive bite deterioration is often accompanied by dull, aching pain in the TMJ region and fatigue in the masticatory muscles during eating.

Diagnostic Evaluation: Radiographs, CBCT, and Clinical Assessment

A thorough diagnostic protocol is essential to determine the location, nature, and rate of progression of the relapse. The clinical evaluation begins with an extraoral and intraoral examination. The clinician assesses the resting facial proportions, smile dynamics, dental midline alignment, overjet (horizontal overlap of incisors), overbite (vertical overlap), and maximum incisal opening. The TMJs are palpated for tenderness, clicking, or crepitus, and the range of mandibular excursions (lateral and protrusive movements) is measured precisely.

Radiographic assessment represents the cornerstone of relapse diagnostics. Standard lateral cephalometric radiographs are taken and superimposed onto immediate post-operative radiographs using stable anatomical landmarks, such as the anterior cranial base (sella-nasion line). Superimposition enables the surgeon to differentiate between skeletal displacement at the osteotomy sites and dentoalveolar compensation, where teeth have tipped to mask a skeletal shift. Orthopantomograms (OPGs) are utilised to evaluate root parallelism, fixation plate stability, and gross condylar morphology.

Cone-beam computed tomography (CBCT) provides volumetric, three-dimensional assessment of the facial skeleton. CBCT is indispensable for evaluating the condylar heads for cortical erosions, flattening, or volume loss pathognomonic of condylar resorption. It also allows precise visual inspection of osteotomy union, screw engagement, and bone stock. In active condylar disease, serial CBCT scans spaced six to twelve months apart, or functional nuclear imaging such as single-photon emission computed tomography (SPECT), may be indicated to confirm that condylar remodeling has burnt out before planning surgical revision.

Classification and Hierarchy of Stability in Orthognathic Movements

In oral and maxillofacial surgery, skeletal stability is understood through established hierarchies based on extensive clinical trials. The classic stability hierarchy categorises surgical movements from most stable to least stable. At the most stable end of the spectrum is the superior repositioning (impaction) of the maxilla, followed closely by mandibular advancement in patients with normal or low mandibular plane angles. These movements benefit from favourable muscular vectors and predictable bone-to-bone contact, yielding high long-term predictability when rigid internal fixation is employed.

Movements with moderate stability include mandibular setback and the combination of maxillary advancement with mandibular repositioning. Mandibular setbacks are vulnerable to forward relapse because the tongue posture remains unchanged and the suprahyoid musculature is compressed, creating an anteriorly directed force against the osteotomised segments. Maxillary advancement alone is generally stable, but large advancements (greater than six millimetres) or movements involving substantial downgrafting require robust bone grafting or rigid fixation to prevent backward or upward settling.

The least stable movements involve maxillary expansion (particularly multi-piece Le Fort I osteotomies without concurrent distraction osteogenesis) and downward repositioning (inferior downfracture) of the maxilla to manage vertical maxillary deficiency. Downward movements pull against strong masticatory muscles that continuously elevate the bone, risking vertical collapse. Counter-clockwise rotation of the occlusal plane, although aesthetically powerful for retrognathic profiles, places high compressive loads on the mandibular condyles and demands maximum fixation stiffness to avert posterior relapse.

Treatment and Management Pathways: From Conservative to Revision

The management strategy for jaw surgery relapse depends on the underlying mechanism, the magnitude of the skeletal discrepancy, the status of the TMJs, and patient symptoms. For minor dental or borderline skeletal relapse (less than two to three millimetres of occlusal divergence), conservative orthodontic camouflage is usually the preferred first-line approach. Utilizing fixed appliances, intermaxillary elastics, or temporary anchorage devices (TADs / mini-screws), an orthodontist can intrude, extrude, or tip teeth to restore an interdigitating, functional occlusion without exposing the patient to the risks of repeat general anaesthesia.

When skeletal relapse is substantial, accompanied by compromised aesthetics or airway obstruction, revision orthognathic surgery becomes necessary. If the relapse is purely mechanical—such as hardware loosening or improper initial segment positioning with healthy, stable condyles—re-osteotomy of the maxilla, mandible, or both can be performed. This involves entering the previous surgical sites, removing the existing hardware, carefully mobilising the bone segments, and refixating them into the planned stable relationship with fresh titanium miniplates and bone grafts where voids exist.

In scenarios where relapse is secondary to advanced idiopathic or progressive condylar resorption, repeat orthognathic osteotomies alone are contraindicated because the unstable condyles will continue to resorb, leading to rapid re-relapse. In these complex cases, the definitive evidence-based standard is alloplastic total temporomandibular joint replacement (TJR) combined with orthognathic reconstruction. Custom-milled or 3D-printed titanium and ultra-high-molecular-weight polyethylene prostheses replace the resorbed condyles and glenoid fossae while advancing the mandible into a permanently stable position.

Step-by-Step Overview of Revision Orthognathic Assessment and Surgery

The revision journey begins with comprehensive virtual surgical planning (VSP). Following high-resolution CBCT scans and optical intraoral surface scans, the surgeon and clinical engineer produce a three-dimensional digital model of the patient's craniofacial skeleton. The previous osteotomy lines and hardware locations are mapped. Custom cutting guides, repositioning splints, and patient-matched custom titanium fixation plates are digitally designed and manufactured via laser sintering, allowing sub-millimetre precision during the operation.

Under general anaesthesia administered via nasotracheal intubation, the surgical team accesses the facial skeleton through intraoral incisions, typically reopening previous scar lines to avoid creating redundant soft-tissue trauma. The surgeon meticulously exposes the bone and dissects the fibrous scar tissue that has developed around the old osteotomies. The previously placed titanium plates and screws are identified and removed using specialised extraction drivers. If scar tissue or bone bridging has united the segments, careful re-osteotomy is performed using piezosurgical instruments or fine reciprocating saws.

Once fully mobilised, the jaw segments are guided into the new occlusal relationship using the CAD/CAM acrylic surgical splint and temporarily secured with intermaxillary fixation (IMF) wires or elastomeric ligatures. Custom-milled or pre-bent rigid titanium plates are adapted across the osteotomy sites and secured with monocortical screws. Autologous bone graft (harvested from the mandibular ramus, chin, or iliac crest) or allograft particulate bone is packed into residual skeletal gaps to promote osteoconduction. The oral mucosa is closed with resorbable sutures, and light guiding elastics are placed to support jaw position upon awakening.

Recovery, Aftercare, and Normal vs Abnormal Healing

Recovery from revision orthognathic surgery requires disciplined adherence to rehabilitation protocols. During the initial two weeks, marked facial oedema (swelling) and ecchymosis (bruising) are standard physiological responses. Patients are maintained on an entirely non-chew liquid-to-pureed diet to prevent mechanical strain across the newly fixated osteotomy interfaces. Post-operative swelling typically peaks between 48 and 72 hours before gradually subsiding over three to four weeks. Sleeping with the head elevated at a 45-degree angle assists in lymphatic drainage.

It is vital for patients to distinguish expected post-operative symptoms from abnormal complications. Normal symptoms include mild intraoral oozing during the first 24 hours, nasal congestion (especially after maxillary surgery), altered sensation or numbness (hypoaesthesia) of the lower lip, chin, and cheeks, and tightness in the jaw muscles. Guiding elastics will maintain the bite, and light jaw opening exercises are introduced gradually as directed by the surgical team.

Conversely, acute deviation of the jaw, an inability of the teeth to fit comfortably into the provided splint, sudden severe malocclusion, or mobile bone segments indicate hardware failure or fixation loosening and represent abnormal findings. Excessive, bright red haemorrhage that does not subside with pressure, worsening unilateral facial swelling after day four, foul-tasting intraoral purulent discharge, or fevers above 38 degrees Celsius warrant immediate clinical evaluation.

Complications of Revision Surgery and Risk Mitigation

Revision orthognathic surgery carries higher technical complexity than primary surgery, primarily due to the presence of dense fibrous scar tissue, altered anatomical planes, and compromised local vascular supply. A major risk is neurosensory disturbance. The inferior alveolar nerve (supplying sensation to the lower lip and chin) and the infraorbital nerve (supplying the midface) are frequently encased in scar tissue, increasing the incidence of prolonged or permanent paresthesia following dissection and plate removal.

Non-union (failure of the bone cuts to consolidate) and fibrous union represent additional risks, especially in patients who have undergone multiple procedures or who have underlying vascular compromise. Bone segments must have adequate blood supply, preserved through careful subperiosteal dissection without stripping excessive soft-tissue pedicles. Where bone contact is suboptimal, primary bone grafting is mandatory to eliminate structural dead space. Strict smoking cessation is essential, as nicotine drastically impairs capillary revascularisation and increases the rate of non-union and hardware infection.

Infection of the fixation hardware is another recognised complication, potentially requiring prolonged antimicrobial therapy or secondary plate removal once the osteotomy has achieved bony union. Surgeons mitigate these risks by using perioperative intravenous antibiotics, maintaining meticulous sterile technique, employing piezosurgery to minimise thermal bone necrosis and soft-tissue injury, and designing custom plate constructs that distribute bite forces evenly across healthy cortical bone.

Prevention, Retention, and Long-Term Surveillance

Preventing relapse begins with meticulous pre-operative planning and continues long after surgical hardware has integrated. Proper pre-surgical orthodontic preparation is paramount: the dental arches must be fully decompensated—meaning the teeth are uprighted within their respective alveolar housings—so that skeletal movements are not artificially restricted. Intraoperatively, passive seating of the mandibular condyles into the glenoid fossae during fixation is the single most critical surgical step to prevent immediate post-operative skeletal shifting.

Post-surgical retention protocols must be observed rigorously. Orthodontic retainers, whether fixed lingual bonded wires, vacuum-formed clear retainers (Essix), or acrylic Hawley retainers, preserve dental positions and prevent minor tooth drift from undermining the surgical result. For patients with a history of bruxism or parafunctional clenching, a custom hard occlusal splint (nightguard) should be constructed once orthodontic finishing is complete. This appliance shields the TMJs and fixation sites from destructive nocturnal forces.

Long-term clinical and radiographic surveillance is advised for at least two to five years post-surgery. Regular reviews allow the multidisciplinary team to monitor TMJ stability, check soft-tissue profile adaptation, and detect early occlusal micro-shifts before they evolve into full-scale skeletal relapse. Patients must also manage contributing systemic or behavioural factors, including seeking myofunctional therapy to retrain atypical swallowing patterns and refraining from chewing habits like paan or hard tobacco products.

Evidence and further reading

The management and understanding of orthognathic relapse are well documented in international maxillofacial literature. Standard guidelines and clinical stability hierarchies stem from landmark longitudinal studies published by authorities such as the American Association of Oral and Maxillofacial Surgeons (AAOMS) and the British Association of Oral and Maxillofacial Surgeons (BAOMS). These publications consistently highlight that multi-directional surgical stability is heavily influenced by the direction of movement, the fixation modality chosen, and individual TMJ health.

The British General Dental Council and the National Institute for Health and Care Excellence (NICE) emphasise the need for multidisciplinary planning involving both specialist orthodontists and consultant maxillofacial surgeons to minimise surgical revision rates. Extensive research published in the *International Journal of Oral and Maxillofacial Surgery*, the *Journal of Cranio-Maxillofacial Surgery*, and the *American Journal of Orthodontics and Dentofacial Orthopedics* validates the efficacy of alloplastic total joint replacement over repeat osteotomy in cases complicated by active progressive condylar resorption. Patients seeking deeper insights should consult their hospital's maxillofacial unit or read peer-reviewed educational materials provided by national surgical associations.