1. The provisions of the Civil Liability Act 2002 (the CL Act) apply to the MAI Act in determining issues of causation. Particularly ss 5D and 5E of the CL Act.[8] In Raina v CIC Allianz Insurance Ltd[9] Campbell J stated:

"One may accept that a review panel is engaged in a process of dispute resolution by expert assessment of medical issues arising under the Act. However, the questions arise in a legal context and it is incumbent upon the panel, medical practitioners they may be, to correctly apply the law including the law of causation in the exercise of their powers. This includes the provisions of Division 3 of Part 1A of the Civil Liability Act 2002 (NSW), ss5D and 5E: see s 3B(2)(a) of that Act. Although it may be expected that questions about the appropriate scope of liability will arise but rarely."

1. Further, cls 6.5 to 6.7 of the Guidelines refer to causation of both injury and whether the degree of permanent impairment is caused by injury.

"There is no simple common test of causation that is applicable in all cases, but the accepted approach involves determining whether the injury (and the associated impairment) was caused or materially contributed to by the motor accident. The motor accident does not have to be the sole cause as long as it is a contributing cause, which is more than negligible."

1. The Medical Assessor noted the injury referred for assessment was the "fracture top of the left mandible requiring open reduction/internal fixation of the fracture left angle of the mandible".
2. The Medical Assessor noted pre-existing loss of teeth due to decay. Current symptoms were dysfunction with pain on eating and occasional "lock jaw". Clinical examination showed no evidence of loss of sensation in the distribution of the trigeminal nerve, bilateral (mostly left) temporomandibular joint (TMJ) dysfunction and multiple carious teeth.
3. The Medical Assessor diagnosed that the motor accident caused a fracture of the mandible and TMJ dysfunction. The Medical Assessor opined that the condition was not stable due to need for treatment but if it was assessed, then the level of whole person impairment was 0%. This conclusion was because the claimant was restricted to a soft diet due to pain and occlusal derangement rather than physical injury.

1. Concurrently with this Review, a differently constituted Panel is determining the review of the medical assessment certificate issued by Medical Assessor Berry.

1. The parties filed bundle of documents for the Panel's consideration.

1. There are no relevant pre-accident symptoms. However, the claimant had decayed teeth and had not seen a dentist. This aspect is discussed later in these Reasons.

1. The ambulance report noted the motor accident with the claimant reporting pain to the left forehead, left cheek, left jaw, left shoulder, guarding to left abdomen, pain to left hip and bleeding to the face.[10]
2. The hospital records note closed reduction of the left hip on 24 July 2019 and open reduction and internal fixation of the mandible fracture and patella fracture on 29 July 2019.[11]
3. The CT scan of the brain dated 24 July 2019 showed no acute intracranial haemorrhage or other herniation, left mandible fracture, Grade II splenic laceration, left clavicular fracture, fracture of the left acetabulum with bone fragments postero-laterally and a dislocated left femur.[12]
4. The X-ray of the mandible dated 31 July 2019 showed a strong plate fixation of the left angle of the mandible fracture which involved the root of 3-8 with minimal residual displacement. Dental review was recommended in respect of large carries at various teeth.[13]
5. A certificate of capacity dated 1 August 2019 noted fractures to the pelvis, left mandible, left clavicle, left patella and hip dislocation.[14]

1. Dr Curtis, Oral and Maxillofacial surgeon was jointly qualified by the parties and provided a report dated 5 September 2023.[15] The doctor noted a history of a reduced ability to chew hard food and that the claimant's teeth did not come together following the operation with a reported weight loss of between five and 10 kilograms.
2. Dr Curtis noted that there was some evidence of mild temporomandibular joint dysfunction on the right and left-hand side and multiple teeth were carious. The doctor noted that the CT radiograph assessment dated 24 July 2019 indicated a communicated fracture of the left angle of the mandible and the fracture appeared to be through the roots of the lower left third molar.
3. Clinical examination showed minor scarring in the left and lower lip and left eyebrow with no loss of sensation in the distribution of the trigeminal nerve. There was mild temporomandibular joint dysfunction on the right and left side and multiple teeth were carious. The miniplate used in the left mandibular region was palpable.
4. Dr Curtis opined that the accident caused a level of temporomandibular joint dysfunction following the surgery carried out at the hospital and combined with a fracture of the jaw, has reduced the claimant's ability to chew hard foods. The doctor assessed permanent impairment based on the reduced ability to chew hard foods at 4%.

Claimant's submissions dated 23 December 2024[16]

1. These submissions were filed in relation to review of the medical assessment.
2. The claimant submitted that she denied that she declined to seek treatment. It was otherwise submitted that the Medical Assessor failed to assess the whole person impairment. It noted that the Medical Assessor formed the view that the motor accident caused the fracture of the mandible and TMJ dysfunction based on relevant hospital records.
3. The claimant noted that the Medical Assessor found TMJ dysfunction with pain on eating and occasional "lock jaw" and that it was getting worse. Reference was made to the assessment under AMA4, Table 6, page 231 and clause 6.197 of the Guidelines.
4. The claimant referred to cl 6.34 of the Guidelines which referenced "a subsequent and unrelated injury or condition resulting in permanent impairment in the same region:"
5. The claimant submitted that there was a requirement to apportion between the whole person impairment related to the accident and that which is not related.

1. These submissions were filed opposing leave to review the medical assessment. The insurer noted that the claimant required treatment from a prosthodontist and that the condition was not stable until this treatment occurred. It submitted that the claimant was not intending to have treatment and could not be critical of the Medical Assessor in proceeding to make an assessment in accordance with cl 6.28 of the Guidelines.
2. The insurer further submitted that the inability of the restriction to a soft food diet was due to pain and occlusal derangement which was unrelated to the injuries caused by the motor accident.

1. Ms Wilson was examined by both Medical Assessor Curtin on 24 September 2025. The assessment was delayed due to the claimant's previous non-attendance. The examination report is as follows:

"The claimant was accompanied by a support person, Ms Cara Avery.

Ms Wilson sustained injuries on the 24 July 2019 when she was the front seat passenger in a van which T-boned another vehicle in a high-speed collision at an intersection. When the ambulance arrived, Ms Wilson was fully conscious but unable to walk. She was bleeding from the mouth and complained of pain in the left shoulder, left abdomen and left leg. She was 20 weeks pregnant.

She was transferred to Westmead Hospital where she was admitted. She was diagnosed with having sustained a dislocated left hip with acetabular fracture, fractures of the left clavicle and left patella together with a grade 2 splenic laceration. Facial examination revealed a laceration of the left eyebrow and abrasions of upper and lower lips. There were no intraoral lacerations, but a malocclusion was present. A CT brain report in reference to the jaw, stated only "left mandibular fracture. Right mandible intact. TMJ enlocated bilaterally". A comment in the notes from an RMO added "left angle of mandible comminuted fracture displaced, appears to be through 38 root, as such should be considered open". On 29 July 2019, she underwent an open reduction and internal fixation of the mandibular fracture via an intraoral approach. Fixation was obtained via a single 2 mm miniplate fixed with 4x6 mm screws. The posterior tooth in the fracture line (tooth 38) was not removed, and no intermaxillary fixation was used. An OPG x-ray was taken following surgery which noted that there was minimal residual displacement and that the fracture involved the root of 38. Large dental caries is noted involving teeth 17, 26, 27, 37 with suspected caries at teeth 13 and 12.

Her post-operative progress in respect of her jaw injury was uneventful. She started on a purée diet. Her weight during the admission was recorded at 60 kg. She was discharged from hospital on 1 August 2019 with arrangements made for follow-up in the plastic surgery outpatients, although there is no indication in the documents that she ever attended this appointment.

The documents contained General Practitioner reports from the Greater Western Aboriginal Health Service at Mount Druitt covering the period 13/08/19 to 04/02/2020. Her weight on the 14/08/19 was recorded at 50.4 kg. An entry dated 20/08/19 stated "diet fruit and veg every day. Mostly home-cooked meals. Nil issues". An entry dated 09/12/19 stated "jaw.. Feeling good, eating normally".

At the time of the accident Ms Wilson was unemployed. She has since started training as a chef, and at the time of this assessment had almost completed her course and was in full-time employment as a chef.

Ms Wilson said that generally she was now able to enjoy a normal diet, although she was unable to manage hard foods such as apples or raw carrots because of pain in her jaw. She said that prior to the accident she had no problems eating such hard food. She said that her jaw was generally free of discomfort, but in cold weather she experiences soreness in the left side of her jaw, pain which was relieved by the application of heat. She also said that from time to time she experienced jaw locking, which lasted only seconds, after which she was able to eat and speak normally. She said that she was aware of some numbness of her left lower lip following the accident. Ms Wilson also said that she was aware of a small scar above her left eyebrow, and she felt that there was some persistent swelling along the left side of her jaw ever since the accident.

Ms Wilson was a fit looking, moderately overweight aboriginal lady of 29 years. She had a light olive complexion, dark hair and weighed 80 kg. She had a pleasant manner, was well-groomed and was fully cooperative with the assessment. There was a 2 cm noticeable, indented scar just above the left eyebrow, and a fine line scar near the hairline, but there were no other visible scars, and her face had a generally symmetrical appearance.

Ms Wilson had a full range of jaw opening, and slight TM joint crepitus could be palpated during repeated jaw movement. The left side of her mandible was not tender to palpation. There was a degree of persistent malocclusion with the lower arch dental centre line shifted 3 mm to the right together with a minor degree of posterior crossbite on each side. The molar teeth in all 4 quadrants consisted only of root stumps. Both upper lateral incisors (teeth 12 and 22) were carious, but the remaining teeth, and her oral hygiene generally were in a reasonably good condition. There was a small area of altered sensation in the lateral half of the left lower lip.

Results of any additional investigations since the original Medical Assessment Certificate

As a result of the jaw fracture, Ms Wilson has a minor degree of persistent malocclusion, and a small area of altered sensation in her lower lip. The persistent malocclusion is likely to have given rise to symptoms of TMJ discomfort and intermittent jaw locking.

In regard to the assessment of jaw injuries, the Guidelines (paragraphs 6.194 - 6.198) direct the Medical Assessor to Table 6 of page 231 in AMA4. The Guidelines also state (para-6.197) that when considering Table 6, the first category (diet limited to semisolid/soft foods) should be in the range 0-19% rather than 5-19%.

AMA4 also states that "when mastication is being evaluated the ability to eat should be stable and maximum rehabilitation should have been achieved". The clinical examination suggests that her jaw fracture is now fully healed and that maximum medical improvement has now occurred.

The complaint of Ms Wilson that she experiences pain and difficulty when attempting to bite or chew anything that is hard is consistent with the history of injury and the findings on examination. These difficulties are likely to be permanent, and in my view an assessment of 7% WPI would be reasonable.

The altered sensation in the left lower lip is the result of an injury to the mandibular division of the trigeminal nerve. The Motor Accident Guidelines (para 6.173) state that sensory impairments of trigeminal nerve should be assessed by reference to table 9 page 145 of AMA4, and that the words "sensory disturbance" should be added after "neuralgic pain" in the first category of that table. Table 9 indicates that 0 to 14% WPI can apply to mild impairment due to uncontrolled facial neuralgic pain or sensory disturbance. It would not be unreasonable to apply the maximum impairment rating of 14%, but paragraph 6.173 states that the mandibular division of the trigeminal nerve can only attract 30% of whatever value is selected. This would reduce the impairment to 4.2%, and this value should be reduced further by 75 % because only part of the mandibular division appears to be affected. The final impairment rating for sensory loss is therefore 1% WPI (after rounding).

The impairments are combined to give a total of 8% WPI."

1. The review is by way of new assessment of all matters with which the medical assessment is concerned.[17] The Panel conducts a new assessment of all the matters with which the medical assessment is concerned.[18]
2. The Panel, comprised of two specialist medical practitioners, is not required to choose between competing medical opinions and is required to form its own opinion: Insurance Australia Group Ltd v Keen[19] and Insurance Australia Ltd v Marsh.[20]
3. The Panel adopts the examination report provided by Medical Assessor Curtin supplemented by the following further reasons. In part the following reasons are inconsistent with the examination report on assessment of the trigeminal nerve and override that part of the examination report.
4. Symptoms of trigeminal nerve injury were not found by Dr Curtis whose opinion formed the basis of the claim for the assessment of impairment due to the fractured jaw.[21] In Mandoukas the Court held that there is no obligation by a Medical Assessor to consider "a matter [unless it] falls within the ambit of the medical dispute referred for assessment".[22] In these circumstances we do not accept that that assessment of the trigeminal nerve formed part of the medical dispute before the Panel.
5. We accept that the claimant's condition and the diet is limited to semisolid or soft foods. results from the motor accident. We rely in part on the clinical expertise of the Medical Assessor who undertook the examination and the severity of the injuries sustained in the motor accident.
6. There is otherwise further medical expertise within the Panel. Based in part on the examination findings of Medical Assessor Curtin and in part on the clinical records, the Panel makes the following further comments.
7. We are of the view that the claimant has had a poor result from surgical treatment to her fractured mandible following the motor accident. The post-operative Orthopantomogram X-ray suggests that the fracture reduction was less than optimal, the operation report gives no indication that she was placed into intermaxillary fixation before the plate was secured, and possibly the fracture was incompletely reduced before the fracture was fixed. The 2mm miniplate was never designed to be used without intermaxillary fixation post operatively. It is possible that there has been some movement in the fracture line following fixation, particularly with only four screws.
8. The claimant's complaints of restricted diet due to the facial injury and ongoing pain are entirely consistent with the nature of the injury and the less then optimal outcome following surgery.
9. There was a pre-existing condition due to the state of the claimant's teeth from poor dental hygiene. However, there is no objective evidence of permanent impairment of mastication at the time of the motor accident when applying the test under cl 6.31 of the Guidelines. We do not consider that the state of the teeth prior to the motor accident was sufficient to cause a dietary restriction. There are no prior medical history or complaints to establish this, and we could not ascertain a basis for this from the claimant's history. We do not make any deduction for pre-existing impairment.
10. There is reference in the assessment of the original Medical Assessor to other causes for the claimant's present condition. Assuming that the current poor dental state is due to both a combination of a pre-existing condition and a deteriorating condition due to ongoing poor hygiene, cl 6.34 requires a determination of whether there is "objective evidence of an unrelated injury or condition resulting in permanent impairment in the same region".
11. The effective loss of her molar teeth would reduce mastication efficiency but would not result in an inability to manage hard food. Accordingly, we do not find that the present dental condition unrelated to the motor accident results in permanent impairment in the same region. No deduction is made pursuant to cl 6.34 of the Guidelines.
12. AMA 4 allows up to 19% WPI for someone whose diet is limited to semi-solid/soft foods. Ms Wilson has intermittent jaw locking of some type, discomfort with heavy mastication and some mild TMJ crepitus. What is going on at the fracture site is unclear but interfering with mastication. The Panel has accepted that the current impairment based on these physical symptoms in somewhere in the mid-range of class 1.
13. We are satisfied that the impairment is permanent within the meaning of cls 6.19 and 6.20 of the Guideline. This is because, whilst treatment may be required, the claimant has taken no steps over the previous six years to have any treatment since being discharged from hospital. Treatment was recommended by Medical Assessor Nichols, and no treatment has been undertaken. There are no plans for further treatment. At the examination, the claimant was once again asked if she would be prepared to see a Prosthodontist, and once again was unable to say whether or not she was prepared to proceed. Given the absence of past treatment other than that undertaken immediately following the motor accident, we consider it extremely unlikely that further treatment will occur. We certainly do not see the claimant undergoing dental treatment in the next 12 months.
14. The Medical Assessors' clinical examination of the claimant and the Panel's expert opinion is that the impairment is unlikely to be a change greater than 3% over the next year.
15. We have not assessed the forehead scar which was visible when the examination was undertaken by Medical Assessor Curtin as this is being assessed by the other Panel.

1. The Panel concludes that the degree of permanent impairment of the claimant that has resulted from the injuries caused by the motor accident is 7%. A new certificate is attached at the commencement of these Reasons.
2. There is another Panel determination which will, depending on the outcome in that matter, provide a revised combined certificate.

[2] See Division 7.5 and Schedule 2, cl 2 of the MAI Act.

[5] Section 7.26(5) of the MAI Act; claimant's bundle, page 303.

[8] See s 3B(2) of the Civil Liability Act 2002.

[9] [2021] NSWSC 13 (Raina) at [65].

[19] [2021] NSWCA 287 at [40], [41] and [45].

[20] [2022] NSWCA 31 at [11], [21], [64]. All

[21] Mandoukas v Allianz Australia Insurance Ltd [2023] NSWSC 1023 (Mandoukos).