What are Incognito braces and what are they used for?

About orthodontics in general


Orthodontics is an important area of dentistry, which is mostly concerned with the realignment of malpositioned teeth and sometimes jaws. Malpositioned teeth have been an issue affecting humanity since prehistoric times. The severity of orthodontic conditions can range from mild aesthetic issues to debilitating problems affecting the quality of life severely. Orthodontic conditions include for example malocclusions, crooked teeth, gaps between teeth, overbites, underbites, or crossbites.

Some early forms of orthodontic treatments have been observed in archaeological samples of ancient cultures, such as Egyptian mummies, however orthodontics started to truly develop in the early modernity. Edward Angle, an American dentist created a system for the classification of different types of malocclusions, a system which is still in use today. Prior to the 1970s orthodontic treatments were primarily dominated by either different types of headgear or braces where the metal wires were wrapped around each tooth.

The mid 1970s marked by significant improvements in dental adhesives brought the braces we know today, consisting of brackets adhered to the surface of the teeth and wires. Metal appliances in one’s mouth can be considered annoying by some, and some people also associate aesthetic impairment with them. The orthodontic developments of the late 1990s and the 21st century have somewhat addressed these issues through for example the invention of invisible aligners, lingual braces and various other types of treatments. If you think you would benefit from some type of orthodontic treatment, do not hesitate to book yourself a consultation session at our dental clinic, Weybridge Orthodontics.

What exactly is Incognito?

Incognito in Weybridge  is an innovative type of orthodontic treatment, which addresses the aesthetic concerns some patients may have about traditional braces. Incognito braces are placed on the inner surfaces of the teeth, making them nearly invisible. They consist of custom made brackets, archwires and bonding trays. Incognito in Weybridge do not need to be removed when eating or drinking, unlike some other forms of orthodontic treatments, such as invisible aligners. Therefore they fit the lifestyle of patients who do not like the idea of having to remove, clean and maintain their aligners. These braces are comfortable to wear, and also provide excellent results. They can also treat conditions that invisible aligners would not be suitable for. If you think you would benefit from getting Incognito braces, a consultation session at our dental clinic, Weybridge Orthodontics will help evaluate your condition and whether Incognito braces are a suitable option for you.

What alternatives to Incognito braces exist?

There are various alternatives to Incognito in Weybridge braces available, if for some reason you do not like them or they would not be suitable to treat your specific orthodontic condition. An obvious alternative would be traditional metal braces. Another alternative are invisible fixed braces. With these braces the brackets are made out of a plastic material with a colour identical to the colour of your teeth and the wires are made out of a transparent plastic material. Alternatively, you may choose to get some type of invisible aligner, such as Invisalign. Contact our dental practice to find the treatment option most compatible with your lifestyle and orthodontic condition!

Invisalign – benefits and disadvantages

What is Invisalign and what can it be used for?


Orthodontic conditions are a topic as old as humanity itself. Their severity can range from minor aesthetic issues to serious problems impairing the quality of life. The treatment of these conditions has started to advance mostly in the 19th and 20th centuries. Before the 1970s, orthodontic conditions had been mostly treated by using headgears and metal braces. With the invention of dental adhesives in the mid 1970s the usage of metal braces with brackets became possible. This significantly reduced the aesthetic issues associated with earlier forms of braces and it also reduced the amount of discomfort experienced throughout such treatments.

Later developments in the field of medical plastics have brought invisible braces to the markets. These braces have an identical structure and function to metal braces, but they differ in the material they are made out of; the brackets of invisible braces are made out of plastic that has the same colour as the patient’s teeth, and the wires are made out of transparent plastic. This has significantly reduced the visibility of these braces. Later developments include invisible aligners, with the most famous and the first brand being Invisalign in Weybridge. Invisalign and other plastic aligners are ‘moulds’ of a patient’s teeth, which fit perfectly on the dental arches. During these treatments a series of these aligners are made as the treatment progresses, to achieve optimal results incrementally.

If you think you would benefit from some type of invisible aligner, such as Invisalign in Weybridge, do not hesitate to contact our dental practice, Weybridge Orthodontics in Surrey, to book yourself a consultation session, where we evaluate your orthodontic condition and help you in choosing the best possible treatment option.

What are the benefits of Invisalign?

One of the most obvious benefits of Invisalign in Weybridge is the near invisibility of the plastic aligners. They fit perfectly on your teeth, and they are very hard to notice – unless you mention that you use them. These aligners are removable, which means that you can clean them and brush your teeth without the need of specific toothbrushes required when using traditional braces. Certain types of foods and beverages are known to have remarkable staining capabilities. These include for example coffee, red wine and some fruits as well. If you remove the aligners before consuming any of these you can easily prevent the staining of the aligners. However, it is important to note that they must be worn at least 22 hours a day to achieve the best results.

What are the disadvantages of Invisalign?

As with every type of treatment there are some important disadvantages to consider as well. Invisalign and other invisible aligners are not suitable for every type of orthodontic condition. Severe malocclusions and large gaps between teeth require traditional braces, as Invisalign cannot fit the tooth that must be realigned in these cases. People with very round or small teeth are also not suitable candidates for treatment by Invisalign, as the aligners in these cases cannot get the necessary grip on the teeth. Some patients would also consider the removable nature of these aligners a disadvantage rather than a feature. If you think you are the type of person who cannot always remember to wear these, you should consider an alternative option – there are plenty of them. Invisible aligners require significant patient commitment. Contact our dental practice to find out more about Invisalign and its alternatives.

The solutions modern orthodontic treatments can provide

Orthodontics and its history


Orthodontics in Weybridge is the branch of dentistry, where the main goal is the realignment of misaligned teeth and jaws. Orthodontic conditions date back to prehistoric times – some archaeological samples from 50,000 years ago have been shown to have crooked teeth. Ancient historical authors, such as the very well known Greek physician Hippocrates, were the first to write about treatments of misaligned teeth. Ancient Egyptian mummies have been shown to have metal wires wrapped around their teeth, to which possibly catgut material had been bound to exert pressure in order to realign teeth.

The major breakthroughs in this branch of dentistry however started to happen in the 18th century, primarily in France and later there were significant developments in the US as well. One of the greatest advances was the invention of dental adhesives in the 1970s, which led to the partial solution for the aesthetic issues associated with previous orthodontic treatment methods. Metal braces with brackets adhering to the surface of the teeth were made possible. However, this was still a partial solution only, as most people still do not like the idea of having metal wires and brackets in their mouth for an extended period of time. Luckily today there are many different treatment solutions that address the aesthetic concerns associated with metal braces. Visit our dental clinic, Weybridge Orthodontics if you would like to find out more about what types of orthodontics in Weybridge we offer!

What types of orthodontic treatments work for different types of conditions?

There are a wide range of different orthodontic conditions, which require different types of treatment. One type of treatment may not be suitable for every orthodontic condition, therefore if you think you need some type of orthodontics, a consultation session with us is necessary before starting any procedure.

A popular orthodontic treatment option is Invisalign, high in demand like many invisible aligners, Invisalign consists of moulds of a patient’s teeth made out of a clear plastic material. A series of these aligners are manufactured throughout the progression of the treatment in order to achieve optimal results incrementally.

Another popular option are clear fixed braces. These work on the same principle as traditional metal braces with brackets, with the main difference being in the material of the arch wires and the brackets. Contrary to traditional metal braces, the brackets are made out of a plastic material with a near identical colour of the teeth themselves and a transparent plastic wire.

Another popular option are Incognito lingual braces. These are custom made, personalised braces made out of metal, however in contrast to traditional metal braces, these are located on the inside of the teeth, making them barely visible.

Invisalign and other plastic aligners are usually suitable for the treatment of milder cases of orthodontic conditions. Complicated malocclusions for example cannot be treated by Invisalign or other invisible aligners – these conditions require traditional braces.

If you think you require some type of orthodontics in Weybridge, do not hesitate to contact us and book yourself a consultation session at Weybridge Orthodontics, where we help you find the optimal treatment type suiting both your condition and your lifestyle!

Is Invisalign right for you?

What is Invisalign?


Invisalign is an innovative treatment solution for the treatment of orthodontic conditions. Orthodontic conditions are very widespread and can range in severity from minor aesthetic issues to conditions impairing one’s ability to speak or eat properly and thus having a great impact on the quality of life. Many people who require orthodontic treatment often do not seek it due to aesthetic concerns. This was a significant driving force for research and development of orthodontic treatments and resulted in the invention of invisible aligners, the first and most widely known brand of which is Invisalign. Invisible aligners are plastic ‘moulds’ of a patient’s dental arches, which perfectly fit on them. They are made out of a transparent plastic, which makes them incredibly hard to notice. If you are interested in getting Invisalign in Weybridge, contact our dental practice, Weybridge Orthodontics in Surrey to gain more information about them, and to find out whether they are suitable for you in our consultation session.

What are the benefits of Invisalign?

Probably the most obvious benefit of Invisalign in Weybridge compared to other orthodontic treatments is the invisibility of it. The plastic material the aligners are made out of is transparent, therefore you do not need to worry about someone noticing them, unless you tell them! Another important benefit is the reduced feeling of discomfort. As it is made out of plastic, you will not feel any metallic ‘background’ taste as some do with traditional metal braces with brackets. It will also not irritate you in the sense sharp metallic objects could; the surface of the aligners is smooth, and given their perfect fit on your dental arches they blend into your mouth to the point they are almost unnoticeable. The aligners can be removed and cleaned. This is especially important if you tend to consume drinks or food that could stain the aligners, such as coffee, tea or red wine. They allow you to maintain your normal oral hygiene routine due to their removability.

Are there any disadvantages of getting Invisalign?

As it is with most treatments, no treatment is perfect for every individual. This is true for Invisalign as well. Some conditions and natural characteristics rule out the possibility of getting invisible aligners. One of these is having certain teeth shapes, such as very round or small teeth. If you already have some dental works, such as crowns, bridges or dental implants, invisible aligners may also not be suitable for you.

How does an Invisalign treatment work?

First you need to book a consultation session in our dental clinic, where we evaluate your condition and help you determine whether Invisalign  in Weybridge is the best option for you. This is followed by taking a 3D image of your oral cavity, which helps us in designing your custom made aligners. Once this is done, the aligners are manufactured. A series of them must be worn for a defined period of time. You must wear the aligners for at least 22 hours each day, therefore Invisible aligners require significant commitment on your side. If you think this is not ideal for you, there are always other options, and we would be happy to help you in finding the best alternative for you.

Invisalign in Weybridge compared to other orthodontic treatments

Nowadays, there are a large number of different orthodontic treatments that can be used to address different oral conditions. Because of this large number of treatments, it can be easy for people to potentially become confused about which treatments they may need or which can benefit them. For that reason, it can be a good idea to know more about different orthodontic treatments, and in particular about some of the more new and revolutionary treatments, such as Invisalign in Weybridge.


This is a treatment that can provide great, effective results for you if your teeth are misaligned. If this sounds like something that would interest you, and/or if there are any other orthodontic treatments you have heard about that you believe would interest you, then this article may help you, as in it we’ll discuss Invisalign in Weybridge as well as some other orthodontic treatments in more depth.

Regardless of the orthodontic treatment you choose (if any) then you will want to make sure that you can get this treatment from trustworthy orthodontic specialists. One high-quality option that you may wish to consider is Weybridge Orthodontics. Here at Weybridge Orthodontics, we provide exceptional orthodontic treatment that is carefully structured to fully consider your specific problems and needs and provide the best quality care for them.

Not only do we have a track record of consistently delivering on our promises of high-quality orthodontic care (having treated over 21,000 satisfied patients), we also always ensure that our treatments are delivered in a comfortable and friendly environment and offer convenient appointment and treatment times that suit our patients. Therefore, at Weybridge Orthodontics, you can be sure that whenever or whatever your orthodontic problem may be, we will provide you with the best quality help.


Invisalign in Weybridge is an exciting treatment which can adjust the position of misaligned teeth to gradually shift them into a more favourable position over time. One of the reasons why this treatment is as popular as it is is because it is able to shift the teeth whilst being virtually undetectable to any outside observer. This is because Invisalign uses a set of clear aligners that are worn over the teeth in order to achieve its results.

These aligners are given to the patient in a set. This means that a patient wears the aligner for a given period of time (usually about two weeks) before switching it out for the next aligner in the set. The multiple aligners are what allow Invisalign to keep shifting the position of the teeth. Furthermore, this also means that it is relatively easy to remove the aligners for activities such as eating or drinking.

Other treatment

Another treatment which you may wish to consider is a mouthguard. A mouthguard is somewhat similar to Invisalign in that it covers the surface of the teeth, however, it is more designed to prevent damage being done to them whilst playing sports. There is also a ‘Twin-block’ treatment, which is often aimed at teenagers. This treatment is designed to realign the jaw, and it is useful for ensuring that top teeth are the ideal length in front of bottom teeth (2 – 4mm).

Teeth Straightening from Weybridge Orthodontics

Having a nice smile is an important part of many people’s sense of self-confidence. After all, who wouldn’t want to have a dazzling smile that they can show off to their friends and family? Sadly though, many of us may have teeth that we do not consider to be perfect, or teeth that are misaligned. For many people, having misaligned teeth can put a real dampener on the perceived quality of their smile, and can potentially make them smile less.


The good news though is that hiding your smile doesn’t need to be your only course of action, and there are actually many better orthodontic solutions. For example, one of the orthodontic options worth looking at is teeth straightening. There are a few different treatments that are encompassed by the label of teeth straightening, so today we’ll provide an overview of some of these available treatments, which should potentially allow you to consider whether any of these treatments would be right for you.

When considering orthodontics in Weybridge and the impact that orthodontic treatments can have on your future and current oral health, it is important to look for high quality, specialist orthodontists who can provide you with long-lasting results. Because of this, if you are considering orthodontic treatment, then you may wish to consider Weybridge Orthodontics.

Here at Weybridge Orthodontics, we have assembled a team of specialist orthodontists who have all spent years undergoing rigorous training at prestigious UK dental schools. In addition, we use the latest orthodontic technology available, including sophisticated computer graphics which help to demonstrate predicted treatment outcomes, so you can be sure that with us you will receive some of the best and most up to date orthodontic treatments available from top-quality professionals.

Overview of different teeth straightening options

As mentioned, there are quite a few different examples of teeth straightening treatments that you can receive. One relatively new and popular example is Invisalign. Invisalign is named as such because it is a treatment that straightens teeth by using a set of clear, nearly invisible plastic aligners to gradually shift the position of teeth over time. Invisalign aligners are made to comfortably fit an individual patient’s teeth, and they are provided to the patient in sets. This means that the patient wears one aligner for a period of time – usually about two weeks – before switching it out for the next aligner in the set, which is what allows the patient’s teeth to be gradually shifted into a more favourable position over time.

Another available treatment is Gemini braces. Gemini braces are a treatment that uses metal braces to gradually shift misaligned teeth, and are arguably more similar to what one might think of when hearing the term ‘orthodontics in Weybridge.’ Unlike many conventional braces though, Gemini braces coloured elastic bands give a patient’s braces a more colourful and cosmetically pleasing look. The coloured elastic bands are held in place underneath the Gemini braces’ “brackets” such that they are still visible on top of the teeth. The elastic bands can come in a variety of different colours, and furthermore, the colours of these bands can be changed when a patient attends one of their 8 – 10 weekly appointments with their orthodontist after initial treatment.

How Invisalign in Weybridge works and how to use it

There are many advantages to having a set of full, straight teeth in your mouth. Not only are there cosmetic benefits to having straight teeth, but it can also be beneficial for your overall oral health to have straight teeth as it can make activities such as eating and chewing easier. Whilst some people are blessed with perfectly straight teeth for the entirety of their lives, many of us aren’t quite so fortunate. This doesn’t mean that we can’t have straighter teeth; far from it. There are, in fact, many different orthodontic treatments that can be used to gradually shift our teeth into a straighter and healthier position over time.


One of the most exciting and interesting types of these teeth straightening treatments is Invisalign in Weybridge. There are a lot of advantages to Invisalign in Weybridge, as not only can it adjust the position of a patient’s teeth, it can also do this whilst being practically undetectable to the outside observer. However, you may be wondering about what Invisalign in Weybridge actually is, and how it works. In this article, we’ll take a look at those questions, and demonstrate why Invisalign in Weybridge could be a treatment that is worth your time.

Another important thing to think about when thinking about this, or in fact any orthodontic treatment is which dental clinic can offer you this treatment in a professional way which delivers the results you are looking for. One place that can offer you this that you may wish to consider is Weybridge Orthodontics.

Here at Weybridge Orthodontics, we have a record of treating over 21,000 satisfied patients and we put this record down to our belief that the patient always comes first. Indeed, all of our orthodontic practices are carefully designed to make a patient as comfortable as possible and we always make sure to guide you through different treatment options in a friendly and unpressured environment. Because of this, you can be sure that here at Weybridge Orthodontics you will receive great treatment that puts you first.

Invisalign and how it works

If you are looking for a treatment that can straighten your teeth whilst fitting around your day to day life, then Invisalign may be the treatment for you. This is because it is a treatment that is specifically designed to be discreet. It manages to be discreet by providing you with a set of clear plastic aligners that fit comfortably over your teeth. In fact, the aligners can fit comfortably over any set of teeth, regardless of how different these teeth may be from someone else’s. This is because each Invisalign aligner is specifically designed for an individual patient’s teeth, sometimes using a mould or computer imagery to make sure that the aligners will fit as intended.

It is also worth pointing out that these aligners come in a set. This is so the patient can wear one of the aligners for a period of time – often approximately two weeks – before switching that aligner out for the next aligner in the set. This allows the aligners to gradually shift the position of the patient’s teeth so that they end up overall straighter over time.

Let us unlock your dental dreams through Invisalign in Weybridge

Dare to make a change


Across the nation a growing number of people, of all ages and social demographics, are  seeking cosmetic dentistry solutions, to help them address superficial issues or concerns which they have about the way their smiles look. Here at Weybridge Orthodontics, we welcome this new wave of patients and interest around cosmetic dentistry with open arms. Anyone who feels that their smile could be enhanced or enriched through some of the various cosmetic dentistry procedures that we offer here at Weybridge Orthodontics – such as Invisalign in Weybridge – need only take a look at our website to begin their treatment journey to help them unlock the true potential behind their smiles.

What is Invisalign?

Invisalign in Weybridge is a revolutionary new system of correcting teeth which are crooked or poorly aligned. Our expert cosmetic dentists, here at the practice, are fully qualified and equipped to provide to our patients all the benefits that come with it. Invisalign offers its patients an alternative to conventional orthodontic braces. Without a doubt traditional, fused braces are very effective and successful in their aim to achieve straighter teeth. However through Invisalign in Weybridge patients can undergo dental adjustment and achieve a straighter set of teeth – without anybody noticing that they are undergoing treatment. The ‘discreet’ nature of the Invisalign process has made it one of the most widely sought out methods of cosmetic orthodontics across the world, and it has a notable following within the demographics of teenagers and younger adults. This is largely due to the freedoms that the hidden nature of the process provides, as it allows them to carry on their lives as normal whilst undergoing treatment.

How does it work?

Whilst traditional orthodontic braces operate through the use of fused brackets being bonded to teeth and held together through a tension wire, the Invisalign system is made up entirely of a single retainer. Each of these retainers is built from a mould of the patient’s tooth shape and structure – and as a result fits each patient perfectly and uniquely. Invisalign retainers are constructed from a patented plastic called SmartTrack, and are highly durable, as well as comfortable. Within the interior of each retainer there are specifically placed pressure points. These pressure points – over time – apply force to the specific teeth which are out of line, and slowly shift them into place. Treatment through the Invisalign method is most effective in instances where the misalignment is mild, and typically takes around twelve months to complete.

How do I get Invisalign?

If you feel that the crookedness of your smile could potentially be solved through Invisalign, then take a look at all the options available on our website. In doing so, you can answer all your queries and become completely clued up and familiarised with the process which you may be undertaking. If you do require an initial consultation, this will be the point where one of our practitioners will assess whether or not any underlying oral health concerns you might have could possibly stand in the way of treatment. Providing that all is well however, one of our Invisalign experts will begin to formulate a unique treatment plan, and your path towards a healthier smile will begin. 

What is Orthodontics in Weybridge?

Orthodontics in Weybridge improves misaligned or overcrowded teeth, normally using braces, as well as problems with over/underbites. With six clinics across Surrey, Weybridge Orthodontics offers a wide range of treatments to improve misaligned teeth and can help to bring a smile to your face; over 21,000 satisfied patients have already been treated by our highly-qualified staff.


Am I eligible for treatment?

It can sometimes feel daunting seeking advice for an issue that is concerning you or someone you love. It may be useful to know that children, adolescents, and adults can all benefit from orthodontics in Weybridge. When you visit our clinic, we promise to give you the red carpet treatment and a very warm welcome. We have a specialist team who will guide you through your ‘orthodontic journey’ and will ensure that you have all the information you need to receive the best care possible.

On your first visit, you can expect to be greeted by our friendly receptionists who will help you to fill out the paperwork detailing important information, such as your medical history, before you have your consultation with the clinical staff. The purpose of this consultation is to gather your views about the appearance of your teeth.

A clinical examination will also take place, which involves checking the face, jaws, and teeth. Any necessary radiographs, photographs or moulds of your mouth will be taken to enable us to devise a treatment plan with you. We promise to treat you within a reasonable time-frame and we pride ourselves in delivering effective results, no matter how complex the case.

What treatments are available?

Following the clinical examination, and with the benefit of our Treatment Coordinators’ expertise, we will be able to advise you of the options available to you. There are 3 different treatment options: early treatment; interceptive treatment; and adult treatment. For each of these, there is a range of private and NHS routes that may be taken and all of these will be discussed with you.

We offer short 6-month treatments for those with only front teeth issues and where, perhaps, teeth have moved since a previous treatment, to treatments that take longer. Whatever treatment plan is advised, you can be sure to get the best advice to make the right decision for you.

With over 10 different brace systems to choose from, we have the flexibility to offer a great treatment plan that will really help improve your smile. If you’ve never heard of ‘Invisalign’ or ‘Gemini’, ‘Clarity’ or ‘Damon’, then don’t worry! The differences between these braces and brackets, as well as the rest of the range on offer, will be fully explained (don’t worry; we won’t test you afterwards!)

How much will treatment cost?

The cost of treatment will depend on the route taken, but we have a special offer for consultations and a refer a friend scheme, giving you £25 for every friend referred to us. Sounds good? It certainly is; it’s just another reason to show off your new smile once you’ve been treated by us, and your friends have too.

Invisalign in Weybridge – An Introduction

How would you rate your smile on a scale of 1 to 10? We all have things we would like to change about our smile. If your personal rating of your smile is on the lower end of the scale, you may have also considered types of treatment to improve the condition of your teeth and overall smile. This is where our dental practice; Weybridge Orthodontics are here to help.


An introduction to Weybridge Orthodontics in Weybridge

At our practice Weybridge Orthodontics, we know how important the appearance of our patient’s teeth and smile are. This is why we have a wide range of dental treatments for our patients in order for them to achieve their desired result. Based in Surrey, our practice has a trained orthodontist who provides teeth straightening services for our patients.

At Weybridge Orthodontics, we are committed to providing patients with the most suitable dental procedure in accordance with their current dental issues. So if you are considering improving your smile by straightening your teeth; Weybridge Orthodontics can provide you with a full range of options and appliances.

So what treatments do we offer at Weybridge Orthodontics?

Teeth straightening is a popular form of cosmetic dentistry for individuals. In recent years, more and more adults have been looking at the best way to straighten their teeth without the treatment interfering with their daily lives.

If you are a new patient and are considering dental treatment you will be required to come into our practice in order for us to obtain important information about yourself before commencing any type of dental treatment. Our consultation process gives us a chance to carry out a clinical assessment and listen to your needs, wants and any concerns you may have.

One of our highly trained orthodontists, at your initial consultation, will carry out a thorough examination of your teeth along with your mouth and jaw. We will also be required to take x rays and photographs of your teeth. This will allow our orthodontist to correctly diagnose any issues with your teeth along with compiling a suitable teeth straightening treatment plan. However before you agree to our suggested treatment, you will be given a chance to discuss the plan in detail and decide in your own time whether you want to go ahead with the dental treatment.

What treatments are available at Weybridge Orthodontics?

With over 100 years of combined experience, our practice provides teeth straightening services including the Damon Clear, Gemini and Incognito treatment. We also provide a popular dental treatment; Invisalign in Weybridge.

The benefits of Invisalign

A discreet treatment, Invisalign in Weybridge uses 3D technology to gradually straighten an individual’s teeth using clear aligners which are changed weekly or bi-weekly depending on your treatment plan. A reason why Invisalign is so popular, especially with our adult patients, is that the aligners are practically invisible so you do not have to worry about your appearance. They are also removable which means you are able to still enjoy your favourite food and drink as long as you maintain your oral hygiene routine and brush your teeth after each meal.