"I've had more than half a dozen very upset ladies at the counter, some in tears," Ms Wasson said.
"He's been their dentist for 30 plus years in some cases and they now have to make a decision about where to go to from here ... it's very sad for some of them."
He said: "I've met the most wonderful people and now I'm treating their children - and even their children's children."
Many of those patients have come to the surgery bearing gifts for the high-profile dentist, who is known as much for his public anti-fluoridation views as his commitment to caring for the individual needs of his patients.
Dr Brett qualified in 1973 and apart from about four years working in Australia and the UK, he has spent the past 38 years in Kamo.
"I returned [to New Zealand] in 1977 but I hated it - Rob Muldoon was going nuts, damming Manapouri and doing crazy stuff," he said.
"So I returned to Western Australia because I wanted to see wildflowers blooming in the desert," he laughed.
He also wanted to buy a practice in Australia but the cost was prohibitive. A friend alerted him to a practice selling cheaply in Kamo, so he returned to New Zealand.
With friend Laughton King, Dr Brett and his wife Jenny spent a weekend recarpeting and wallpapering the premises, and they were ready to "hang up the shingle and open for business".
Over the years he has seen many changes in the industry, including a shift away from amalgam fillings.
"In my view, the amalgam thing was a terrible mistake. The technique is still taught at dental school but most graduates going into practice immediately have to learn composite tooth-coloured fillings.
"The idea that mercury in amalgam fillings doesn't leach into the body is wrong, in my opinion."
He said he hadn't used amalgam for about 25 years.
Dr Brett said one of the major achievements early in his career was instigating preventative oral hygiene by employing a dental hygienist.
"I was the dentist for Kamo High School and a lot of the kids had really bad teeth from eating junk food. I was the first practice to hire a hygienist and that turned it around - initially I was seeing students needing six fillings across their front teeth but that just doesn't happen now."
He attributes poor dental health at the time to the lifting of restrictions on imported sugar after World War II - and the failure to recognise the need for regular brushing and flossing as well regular visits to a hygienist.
Dr Brett is concerned that access to dentistry is becoming the province of the wealthy and poorer people, especially children, are missing out on treatment.
"By the time you write up a report, take an X-ray and send off an application for government assistance ... the dentist ends up doing the work voluntarily."
Dr Brett is considering volunteer work in countries such as Fiji, as well as in South Auckland, and is also pursuing his passion for singing and playing guitar.
But first the keen surfer will travel to Fiji to visit his son Henry, who has a surfing charter company. He is also going to visit his daughter Anna who is a teacher in Thailand. The Bretts have another son, Tom.
- Dr Malcolm McDiarmid has been practising with Dr Brett since 2000 and he bought the practice in 2010. New graduate Jason Phang starts at the practice on July 7 as Dr Brett's replacement.
