Idiopathic condylar resorption (ICR) is progressive resorption of the condyle of unknown aetiology. There is no consensus on the approaches for diagnostic imaging and management of this disease. The objective of this systematic review was to examine the best practices for imaging and to appraise the success of surgical and non-surgical therapy of ICR. Eleven search engines were queried via explicit literature searches for studies describing ICR, published until 2012. Two authors independently extracted data using predetermined characteristics. Studies that identified patients as having either ICR or progressive condylar resorption and that described the radiographic findings or treatment options were included. Seventeen studies contributing 178 cases met the eligibility criteria. The major radiographic findings, as assessed mostly by two-dimensional imaging, included decreased ramus height, decreased condylar height, altered volume of the condyle, decreased SNB angle and mandibular plane angle, and a retrognathic profile. Treatments included occlusal splints with orthodontic treatment, condylectomy with costochondral graft, and other surgical approaches. This systematic review was limited by the lack of meta-analysis. Nevertheless, we identified the need for future investigations: characterization of findings on three-dimensional imaging and its contribution to treatment planning, outcomes of non-surgical and pharmacological management of ICR, and randomized trials and comparative studies with longer follow-up periods.
Idiopathic condylar resorption (ICR) is known by different terminologies including idiopathic condylysis, aggressive condylar resorption, and progressive condylar resorption. ICR is a relatively well-documented but poorly understood condition of the temporomandibular joint (TMJ). Condylar resorption was first reported by Burke in 1961. It was then labelled as acquired condylar hypoplasia. Progressive condylar resorption was first documented as a discrete pathological entity in 1977. The term progressive condylar resorption appropriately describes the progressive nature of this disease, a hallmark feature of the condition. However, the term ICR has been used more frequently, to underscore the unknown aetiology of this condition. Subsequently, Phillips and Bell reported a case of condylar resorption following sagittal split osteotomy (SSO). The authors speculated that altered biomechanical forces following increased muscular tension led to the resorption. Since then there have been sporadic reports of condylar resorption of unknown aetiology in the literature. Crawford et al. reported seven cases of condylar resorption. Since there was no attributable cause for the condylar resorption, they used the term idiopathic and introduced the terminology of ICR. Arnett et al. proposed that dysfunctional remodelling of the condyle results from either a decreased host adaptive capacity or increased mechanical stresses. They proposed three important categories of factors that determine condylar remodelling: age, systemic factors, and hormonal factors.
Previous studies and case reports of ICR have characterized this disease as a rapidly progressing and extensive condylar resorption that cannot be attributed to known pathological conditions such as rheumatoid arthritis (RA) or osteoarthritis (OA). A diagnosis of ICR is based on patient history, clinical and imaging findings, and appropriate exclusion of known causes. The pathogenesis of ICR remains unknown to date.
Although the clinical manifestations of ICR have been described extensively, the radiographic appearance and its correlation with disease progression or arrest have not been adequately explored. Traditionally ICR has been identified using conventional two-dimensional (2D) radiographic modalities such as panoramic or lateral cephalometric projections, where ICR is recognized as loss of condylar volume. Importantly, there is no clear consensus on the management approaches for this condition. Treatments have ranged from conservative therapy with occlusal splints to invasive surgical approaches for disc repositioning, SSO, condylectomy with costochondral graft (CCG), or a combination of these surgical techniques. Unfortunately, the data on treatment-related outcomes have not provided clear guidelines for the management of ICR. For example, it is important to define imaging protocols, to select such protocols based on specific clinical situations, and to discern specific imaging findings that may contribute to guide management and predict the therapeutic response. Equally important, the selection of suitable treatment approaches and their long-term outcomes have not been defined explicitly. The absence of such evidence-based guidelines makes evidence-based management of ICR challenging.
In this systematic review we collate and critically evaluate the literature on ICR, with specific emphasis on radiographic examination, management approaches, and treatment outcomes. The rationale for this systematic review is to provide information on the current state of knowledge, the limitations of previous studies, and importantly to identify critical gaps in knowledge that could be addressed by future studies. Thus, to examine the best practices for imaging, and to appraise the success of surgical and non-surgical therapy, we reviewed randomized controlled trials and case series that assessed diagnostic imaging and management of patients with ICR.
Materials and methods
This systematic review has been presented in accordance with the PRISMA guidelines for reporting a systematic review. Currently, there are no existing review protocols for ICR. Prior to the start of this systematic review, we defined the search strategy and sources, inclusion/exclusion criteria, methods of data collection and analysis, and the list of data items to be collected. A flow chart describing the identification, screening, and inclusion of studies is shown in Fig. 1 .
The study and report characteristics that constituted our eligibility criteria are described below.
We included studies of patients diagnosed with ICR/progressive condylar resorption, or with extensive condylar resorption without any attributable cause. All studies that described condylar resorption due to systemic causes (for example, RA) were excluded.
Types of interventions
We included studies that described radiographic findings and studies that described surgical or non-surgical approaches to manage ICR.
‘The geographical distribution, the use of the various imaging modalities and the rationale for their use if stated, and the imaging findings were reviewed’. The successful outcome of therapy, as defined by the number of years of relapse-free follow-up was also reviewed. No constraints were placed on the period of follow-up.
Given the lack of standardized approaches to diagnostic imaging or therapy, the above outcome measures were not compared to a specific diagnostic/treatment approach. Rather, the outcomes from the various diagnostic imaging and treatment groups were compared with each other.
Types of studies
All randomized controlled trials, clinical studies, and case series satisfying the above criteria were included. All single case reports of ICR were excluded; this was because single case reports may not add much information on the radiographic findings and management outcomes.
Only published studies were considered in this review; unpublished materials were not considered. Reports were considered if they provided sufficient data on the population, intervention, and outcome as detailed above.
Information sources, search strategy, and study selection
This systematic review for ICR was conducted by an explicit search of the literature published until 2012. Two authors (KS and FK) searched the following databases: PubMed, Medline (Pre-Medline and Medline), Cochrane Database of Systematic Reviews (Evidence-Based Medicine), Dentistry and Oral Sciences Source, Access Science, Embase, Evidence-Based Medicine Reviews Multifile, Google Scholar, ISI Journal Citation Reports, LILACS, and Ovid Multi-database. A last search was run on 31 December 2012.
The specific search terms used were ‘idiopathic AND condylar AND resorption’, ‘progressive AND condylar AND resorption’, and ‘aggressive AND condylar AND resorption’. Whenever needed, the non-English literature was translated using Google translator. Searches were also conducted using medical subject heading (MeSH) terminology ‘mandibular condyle’ for relevance to ICR.
Eligibility criteria were reviewed independently by two authors (KS and FK), who initially screened titles and abstracts for relevance to this systematic review. The resulting subset was evaluated using the eligibility criteria described above. The articles identified by either of the reviewers as eligible for inclusion were retrieved in full text. The two authors independently assessed the full text records for inclusion in this systematic review. Differences in selection between the two authors were discussed and consensus reached.
Process for collection and summarization of data items
From each of the eligible studies, the demographic details (geographic region), radiographs examined, radiographic findings, management approaches, follow-up period, and relapse rates were recorded. The absence or lack of detail for specific data items was also recorded. Data from individual studies were extracted by KS and validated by FK; disagreements were resolved by discussion.
Risk of bias in individual studies and across studies
To minimize the risk of bias in the outcomes collected, our selection criteria were developed to include only those studies that provided adequate information on the outcome measures. Given that the literature on ICR is sparse, we considered that the results of our systematic review could manifest an operator- or institution-specific bias, skewed by the experiences of specific research groups who are experienced in the management of this complex, challenging disease. Thus, for the publications evaluated, we also collected data on the authors and their institutions.
Study selection and characteristics of the studies included
After removal of duplicates, a total of 282 articles were found in a search of all the databases with the search expressions relevant to our study. The titles and abstracts of these articles were reviewed for relevance to the systematic review. Of these, 53 articles were evaluated for compatibility with our inclusion and exclusion criteria. Articles were excluded from this systematic review either because they did not clearly identify cases as ICR/progressive condylar resorption, or because the radiographic findings and details of treatment were not explicitly mentioned. Finally 17 full-text articles that satisfied the inclusion and exclusion criteria were selected for extraction of the data to be included in this systematic review ( Fig. 1 ). All 17 studies were case series. Our search did not identify any randomized clinical trials. These 17 studies had patients identified as either ICR or progressive condylar resorption, describing the radiographic findings, treatment options, and a relapse-free follow-up period.
Number of ICR cases
The 17 reports contributed 178 cases of ICR. Of these, 70 cases were from the USA (six reports), 62 from the Netherlands (six reports), 17 from South Korea (one report), 11 from Switzerland (one report), 10 from France (one report), six from Japan (one report), and two from Germany (one report). There were no reports from the continents of Africa and Australia/Oceania. Tables 1 and 2 list the studies included and also summarize the radiographic findings, management approaches, and treatment outcomes.
|Arnett and Tamborello (1990)||USA||Panoramic radiograph, lateral cephalogram||Diminished volume of condyle|
|Moore et al. (1991)||Netherlands||Panoramic radiograph, lateral cephalogram||Decreased posterior facial height, condylar resorption on anterosuperior aspect|
|Crawford et al. (1994)||Netherlands||Panoramic radiograph||Radiographic evidence consistent with findings of ICR. However, radiographic findings of ICR not described. Loss of condylar height mentioned for one case|
|Scheerlinck et al. (1994)||Netherlands||Panoramic radiograph, lateral cephalogram||Partial to complete loss of condyle, decreased ramus height|
|Merkx and van Damme (1994)||Netherlands||Panoramic radiograph||Diminished volume of condyle and alteration of the condylar contour|
|Wolford and Cardenas (1995)
Wolford and Cardenas (1999)
|USA||Serial cephalograms, serial tomograms, MRI||Lateral cephalograms: (1) bilateral – dental and skeletal class 2 deformity, anterior open bite, high mandibular occlusal plane angle, decreased vertical ramus height, angulated lower incisors, decreased oropharyngeal airway space; (2) unilateral – unilateral dental and skeletal class 2 deformity, vertical height difference at mandibular lateral borders, ramus and occlusal plane, open bite on contralateral side
Tomography findings: Excessive joint space because of hyperplasia of synovial tissue, decreased condylar size, loss of integrity of condylar cortex
MRI: Decreased condylar volume, bilateral anterior disc displacement with and without reduction, thinning or erosion of condylar cortex, thick amorphous appearing soft tissue in joint space
|Hoppenreijs et al. (1999)||Netherlands||Panoramic radiograph, lateral cephalograms||Decreased condylar volume and ramus height. Patients with deep bite tended to have resorption on the superior side of the condyle and patients with anterior open bite tended to have resorption on the superior and anterior sides of the condyle|
|Hwang et al. (2000)||Switzerland||Panoramic radiograph, lateral cephalograms||Increased MPA, small SNB angle, overbite, overjet, decreased posterior facial height, resorption on anterosuperior aspect of the condyle|
|Borstalp et al. (2004)||Netherlands||Panoramic radiograph, lateral cephalograms||Altered condylar configuration and volume, decreased ramus height|
|Hwang et al. (2004)||South Korea||Panoramic radiograph, lateral cephalograms||Increased MPA, small SNB angle, overbite, decreased post facial height|
|Teitelbaum et al. (2007)||France||Panoramic radiograph, CT scan||No radiographic findings reported|
|Mercuri (2007)||USA||Panoramic radiograph, CT scan||Flattened condyles, progressive resorption leaving only remnant of medial pole, loss of TMJ architecture and substrate with anterior open bite|
|Troulis et al. (2008)||USA||Lateral cephalogram, panoramic radiograph, 99m Tc-MDP bone scan||Reduced bite, increased overjet, increased MPA, decreased SNB and RCUH decreased|
|Gunson et al. (2009)||USA||Lateral cephalogram, CBCT||Lateral cephalogram: Steep mandibular occlusal plane, anterior open bite
CBCT: Flat condylar surfaces, decreased condylar volume, pseudocystic lesion and cortical erosion
|Wohlwender et al. (2011)||Germany||Panoramic radiograph, lateral cephalogram||Small SNB angle, decreased condylar volume|
|Kobayashi et al. (2012)||Japan||Lateral cephalogram and CT scan||Lateral cephalogram: Small SNB angle, a wide MPA
CT: Erosions or deformities of the condyles, or both
|Authors||No. of ICR cases||Management approach ( n )||Relapse (%)||Follow-up period|
|Arnett and Tamborello (1990)||6||Orthognathic surgery (6)||5 (83.3%)||1–39 months|
|Moore et al. (1991)||5||BSSO with or without Le Fort I or midline or both osteotomy (5)||5 (100%)||6–24 months|
|Crawford et al. (1994)||7||BSSO (7)||5 (71.4%)||12–68 months|
|Scheerlinck et al. (1994)||8||NIA||NIA||NIA|
|Merkx and van Damme (1994)||8||Orthognathic surgery (4)
Occlusal splint and orthodontic treatment (4)
|Wolford and Cardenas (1995)||12||Removal of hyperplastic synovial tissue, repositioning and stabilizing disc, ramus SSO and maxillary osteotomies (12)||0 (0%)||18–68 months|
|Wolford and Cardenas (1999)||2||Removal of hyperplastic synovial tissue, repositioning and stabilizing disc, ramus SSO and maxillary osteotomies (2)||0 (0%)||17–144 months|
|Hoppenreijs et al. (1999)||26||Splint, orthodontics (13)
BSSO with or without Le Fort I osteotomy (13)
|Hwang et al. (2000)||11||NIA||NIA||NIA|
|Borstalp et al. (2004)||8||NIA||NIA||NIA|
|Hwang et al. (2004)||17||NIA||NIA||NIA|
|Teitelbaum et al. (2007)||10||Maxillary osteotomies (1)
Mandibular osteotomies (5)
Bibasilar osteotomies (4)
|0 (0%)||12 months|
|Mercuri (2007)||8||Alloplastic TMJ reconstruction (5)||0 (0%)||>12 months|
|Troulis et al. (2008)||15||Condylectomy with CCG (15)||0 (0%)||>12 months|
|Gunson et al. (2009)||27||NIA||NIA||NIA|
|Wohlwender et al. (2011)||2||NIA||NIA||NIA|
|Kobayashi et al. (2012)||6||NIA||NIA||NIA|