overshot teeth made in china

Undershot is a class III malocclusion that is also referred to as mandibular prognathism, maxillary brachygnathism, mandibular mesioclusion, or an underbite. This malocclusion is characterized by a shorter upper jaw and a longer lower jaw, resulting in lower teeth that are in front of the upper teeth. While this condition is normal for some breeds, such as Bulldogs, in many breeds it is unusual. An undershot jaw occurs when the lower jaw grows faster than normal and becomes longer than the upper jaw, and is usually evident around 8 weeks of age in puppies. This misalignment can cause soft tissue trauma, such as to the lips. When the incisors meet instead of fitting next to each other, it is called a level bite. When the malocclusion causes the lower incisors to be placed in front of the upper incisors, it is called a reverse scissors bite.

The cause of overshot and undershot jaws in dogs relate to the increased or decreased rate of growth of the upper and lower jaws in relation to one another. This can occur due to a: Genetic disorder Trauma; Systemic infection ;Nutritional disorder; Endocrine disorder; Abnormal setting of puppy teeth; Early or late loss of puppy teeth.

After a quick physical exam, your vet may have to sedate your dog in order to perform a thorough oral exam. This will assess your dog’s skull type and teeth location in relation to the teeth on the opposite jaw. Often, the placement of the upper and lower incisors in relation to one another can determine what type of malocclusion your dog has. Your vet will note any areas of trauma due to teeth striking those areas, and any cysts, tumors, abscesses, or remaining puppy teeth that may be present. A dental X-ray can also help to assess the health of the jaws and teeth. These diagnostic methods will lead to a diagnosis of an overshot or undershot jaw in your dog.

Treatment of a jaw misalignment will depend on the severity of the condition. If your dog has a misalignment, but can still bite and chew food without problems, no treatment may be needed. If the misalignment is caught early in a puppy’s life, it may only be temporary and may correct itself over time. However, there are times when intervention may be needed. If your puppy’s teeth are stopping the normal growth of his jaws, then surgery to remove those puppy teeth may be performed. This may allow the jaws to continue to grow, but will not make them grow. For older dogs who are experiencing pain and trauma due to misaligned jaws and teeth, oral surgery is generally performed to extract teeth that are causing trauma, to move teeth so that they fit, or to create space for a misaligned tooth to occupy. Other therapies include crown reductions or braces.

If your dog is genetically programmed to have an overshot or undershot jaw, intervention can help, but will not slow or stop the abnormal growth of either jaw. Prevent jaw misalignments in puppies by not breeding dogs who have overshot or undershot jaws.

I debated on where to go next, but at the end of the day the most widely used fishing tool has to be an overshot. Some will say why not a spear? Well if you must ask, always go with the strongest fishing tool you can run to catch the fish. And if you run a spear, never plug the I.D. of your fish by breaking it off. Done with that!

The info that follows has been taken from the manuals published on overshots. I realize that paper manuals are a thing of the past, yes, yes at one time fishing tool hands carried massive catalog brief cases full of reference material. Now you have the luxury of your laptop loaded with information. If you have never sat down and read an overshot manual, now might be a good time.

The overshot is highly versatile and efficient tool. There are several different types of overshots, however each overshot is designed to engage a specific size of tubing, pipe, coupling, tool joint, drill collar or smooth OD tool.

The original overshot was developed by Bowen Oil Tools, which is now part of NOV. One thing I will point out is that in the catalogs you will see more than one assembly number for a given OD of Overshot, this came about due to the two locations developing their own variations. I found this information on NOV’s website and thought it was interesting to share.

Bowen™ became a leader in innovation with the creation of the first overshot, the Series 150, in 1935. This tool set the standard for fishing equipment, and the quick acceptance of the tool assured the company partners that their business would be successful. The company continued to create new products, building a reputation for their well tool design and construction.

Currently there are several manufacturers of overshots, NOV (Bowen), Rubicon (Logan) and Applied Oil Tools (Gotco). These overshots are designated by a series number as follows:Series 10 - Sucker Rod Overshot

Overshots may be identified by one of the following, known as “type”:Full Strength (FS) - engineered to withstand all pulling, jarring and torsional strain

The basic overshot (from top down) consists of a top sub, a bowl, grapple, control, and a guide. In addition to the basic components, some overshots (Series 10 and 150) can be dressed with either a:Spiral grapple used if the fish diameter is near the maximum catch of the overshot, or a

The Series 150 Overshot features the ability to packoff on the fish. When the circulating packoff is not used, the fluid circulates down the drillpipe, aroundthe top outside of the fish, through the slip or grapple assembly, around the guide shoe and up the annulus.

When the circulating packoff is used, the annular space between the top outside of the fish and the inside of the lower part of the overshot is packed off, diverting the fluid flow down into the fish, making it easier to release and recover the fish. Packoffs usually are not high pressure devices but will often withstand sufficient pressure to establish circulation through the fish. Third party high pressure packoffs are available from various sources.

The extension can be installed between the top sub and the bowl of the Series 10, 70, and 150 overshots. It is used to extend the overshot bowl to:Allow the grapple to catch farther down on a fish that may be necked down at the top by having been pulled in two, or latched by an overshot and released several times, or to

A stop ring must be used where a fish OD reduces immediately below the catch area to allow the grapple to bite on full-size pipe.Example - catching a Hydril upset or EUE collar. If the upset of collar should pass completely through the grapple, the overshot may not be releasable.

The Series 10 Sucker Rod Overshot is designed to engage and recover sucker rods, couplings, and similar items from inside tubing strings.Basket grapples are recommended for fishing for hardened and ground boxes (Sucker Rod Box).

The Series 20 Sucker Rod Overshot is a short catch tool which provides a means for engaging the exposed portion of a fish too short to be engaged with a Series 10 overshot.Uses basket grapples only

The Series 70 Short Catch Overshot is designed to engage the exposed portion of a fish too short to engage with Series 150 overshots.Uses basket grapple only

The Series 150 Releasing and Circulating Overshot is used to engage, packoff, and retrieve twisted-off lost tubing, drillpipecoupling, tool joint, casing or other similar fish.

A right hand wicker grapple converts a normal right release overshot to left hand release. This grapple is used where you expect to apply excessive right hand torque to release a packer, safety joint, etc. Note: Overshot will have to be released by left hand rotation.

High Pressure Packoff Assemblies:The High Pressure Packoff Assembly is an accessory to the Series 150 Overshots. It is used when high pressure circulation to the fish is required. It consists of a packoff sub with packing and packing rings and is installed between the top sub and bowl of the overshot. By running the packoff sub above the bowl, this design prevents the application of high internal pressures to the overshot bowl. The design of the High Pressure Packoff Assembly allows pressures two to three times the standard overshot packoff to be applied to the fish.

This information comes directly from the NOV manual for the Wide Catch Overshot. This is probably the first and only change to this common tool I know of in my career.

The Wide Catch Overshot provides the strongest tool available to externally engage, pack-off, and pull a fish that has been significantly worn. This tool has similar rugged design features and construction as the industry standard, Bowen Series 150 overshot, with the ability to interchange the Bottom Guide with the full range of existing components used with the standard Bowen Series 150 overshot.

In service, the Wide Catch Overshot (WCOS) takes a positive grip over a large area of fish and is capable of withstanding heavy pulling, torsion, and jarring strains without damage to the tools or the fish.

The WCOS has been designed to significantly increase the catch range of the OD of the fish to be caught, compared to the standard overshot. This enables a greater opportunity for a successful fishing operation in a reduced number of trips, thus reducing overall intervention costs for the operator. In addition to the large catch range, the WCOS has the ability to seal across very large extrusion gaps at both standard and high pressure and provide full circulation through the fish, should it be required.

Connections between the Top Sub/Bowl and Extension Sub have been designed to create a seal. This will prevent the connection from washing out should the overshot be required to be flowed through for a long period of time. In order to lock the Top Sub/Extension Sub to the Bowl from backing off during operation, set screws have become standard and will gall the threads should the connection break free.

The operation of all overshots is identical. The exception being that the Series 150 carries a packoff which provides circulation through the fish. First, determine that the overshot is properly assembled and dressed with the proper size grapple. Make up the overshot on the fishing string (normally it is run connected to the bottom of the bumper sub) and run it into the well. As the top of the fish is reached make sure circulation has been established to clear overshot ID of any plugging. Lower the overshot onto the top of the fish with no rotation at first. A 5,000 pound set down weight will be sufficient to engage the grapple. While lowering the overshot over the top of the fish watch for pressure build up, shut off pumps if any pressure build up is noticed. Should any back pressure be noticed, release the back pressure to allow the grapple to engage the fish. By elevating the string it can be determined, if the grapple went over and engaged the fish. If unable to work overshot over top of fish without rotation, then slowly rotate the fishing string to the right and gradually lower the overshot over the fish. Combined rotation and lowering over top of the fish are important to keep the grapple in the release position. This provides the maximum clearance between the grapple and fish. While lowering the overshot over the top of the fish, watch for torque build up and an increase in pump pressure. A pump pressure build up indicates the overshot has gone over the top of the fish thereby reducing the flow area. Stop rotation (continued rotation could dull the wickers of the grapple) enabling the grapple to set. Allow the right hand torque to slack out of the string and then pull on the string by elevating the string to set the grapple.

To release from the fish, bump down, then simultaneously rotate to the right and slowly elevate the fishing string. It is best to have a clean fishing top before running the overshot.

As shown in Figure 1, the light junk cover of a kind of weak point mills fishing socket and mainly is made up of tool joint 1, light-wall pipe inward dipper 2, milling bit 3, thick pin 4 and thick pin 5; light-wall pipe inward dipper 2 tops and the thick pin 4 of tool joint 1 usefulness are connected with 5 one-tenth assorted words of pin slightly, and milling bit 3 is that welding-on tungsten nitride wolfram steel powder is made on the serrated teeth that is slit in light-wall pipe inward dipper 2 bottoms.

Here, Paddy Dixon, MVB, PhD, MRCVS, professor of equine surgery in the University of Edinburgh’s Division of Veterinary Clinical Sciences, describes common problems horses encounter as their teeth develop, what problems these abnormalities cause, and treatment options.

“Many horses have some degree of overjet,” Dixon says. An overjet, also referred to as an overshot jaw, occurs when the chewing surfaces of the upper incisors (the front teeth) lie slightly in front of the chewing surfaces of the lower incisors. Most times, this slight misalignment does not cause ill effects to the horse.

“If very marked and left untreated in foals, cases of severe overjet may develop into overbite,” he cautions. This condition, commonly referred to as “parrot mouth,” occurs when all of the upper incisors lie in front of the lower incisors, resulting in excess tooth growth on the top row of teeth; this excess tooth growth can sometimes cause the horse to develop a smilelike appearance when the central upper incisors overgrow .

“Overjet and overbite are aesthetically undesirable but surprisingly, these problems rarely cause difficulty in prehension (grasping food),” Dixon notes. If the horse develops these smilelike incisors, veterinarian should evaluate and reduce the excess tooth gradually, ensuring that the underlying pulp is never exposed or overheated during the process. Most horses affected with overjet and overbite also have their top row of cheek teeth slightly in front of the lower cheek teeth, and thus, they develop overgrowths on the front of their first upper cheek tooth and the back of their last lower cheek tooth, as discussed below.

Dixon explained that with both underjet and overjet, the main clinical concern is a misalignment of the horse’s six cheek teeth (three molars and three premolars).

It’s a mouthful to say, and rostrally positioned (positioned closer to the nose) upper cheek teeth can cause a mouth full of problems for horses. Dixon explains that an imbalance in growth rates between maxillary (cheek bone) and mandibular (lower jaw) bone cause this disorder, which is “nearly always associated with incisor overjet or overbite.”

Several problems can arise from the upper cheek teeth being positioned further ahead than the lower ones. “Because the maxillary and mandibular cheek teeth rows are not in full occlusion (bite alignment), localized cheek teeth overgrowth–colloquially termed beaks, hooks, or ramps–develop on the front of the upper cheek teeth,” Dixon explains. “These overgrowths may be pushed against the lips and cheeks by the bit or noseband and so cause mucosal ulceration and bitting problems.”

Wry nose is a condition in which an affected foal’s upper jaw and nose are deviated, or turned to one side, Dixon explains. The teeth associated with this condition always have malocclusion (poor alignment), although most foals can still nurse and in most cases are bright and active.

This condition–in which one or more of an affected horse’s teeth do not develop–has the potential to affect both deciduous (baby) and permanent teeth, although “true” hypodontia most commonly affects permanent teeth, Dixon explains. And while a missing tooth might not seem like a major problem, Dixon explained that its absence can cause long-term damage to the horse’s mouth.

“Developmental hypodontia is relatively uncommon in horses, with the absence of equine teeth usually due to traumatic loss, disease, or age-related wear,” he explains. The main problem associated with missing teeth is overgrowth of the opposing tooth. In these cases overgrowth can be managed with semiannual dental care to prevent the overgrown teeth causing damage to surrounding structures

“The presence of supernumerary (additional) teeth is relatively uncommon in horses, usually developing in the permanent dentition,” says Dixon. He added that supernumerary teeth can be comprised of a single tooth or more than one tooth joined together.

“Equine supernumerary incisors may be more common–or possibly more readily identified–than supernumerary cheek teeth,” Dixon notes. Extra incisors often cause overcrowding and displacement of the normal teeth. In some cases he suggested it is possible to remove the additional teeth using sedation and nerve blocks. “If (the supplemental teeth are) interwoven amongst the other incisors, differentiation of supernumerary and normal teeth is difficult and safe extraction may be impossible,” he notes. In these cases regular veterinary dental care can help keep the horse’s mouth as healthy as possible.

Supernumerary cheek teeth are relatively uncommon in horses and can cause overcrowding and irregular spacing between teeth leading to periodontal disease. Treatment depends on the location of the supernumerary teeth and what problems they cause, he noted. Following careful clinical examination and radiography (X rays), common treatment options include extracting the additional tooth, widening or filling abnormal interdental spaces (that develop painful food packing), and reducing overgrowth.

“Dysplasia, or abnormal development of teeth, can involve the crown, roots, or all parts of the tooth,” Dixon says. “Dysplasias in the gross anatomy include dilacerations (abnormal bending of teeth), double teeth, abnormalities of size, and concrescence (roots of adjacent teeth joined by cementum) of teeth.”

Additionally, he notes that teeth can develop either too large (macrodontia) or too small (microdontia). Amelogenesis imperfecta (a tooth development disorder in which teeth are covered with thin, abnormally formed enamel) is another rare dental disorder in horses, Dixon added.

“Some cases of ‘stepmouth’ and ‘wave mouth’ are caused by mismatched eruption times of opposing permanent cheek teeth, allowing overgrowth of the teeth which erupt first,” Dixon explains.

Smaller and miniature breeds have this type of disorder more commonly than other breeds due to a likely mismatch between the size of their teeth and of the support bones (jaws), Dixon noted, and the steplike or wavelike overgrowths can remain–or even increase in size–throughout an affected horse’s lifetime.

Dixon notes that both deciduous incisors and cheek teeth can be retained past their normal time of shedding. In some cases, he noted, this will cause the permanent tooth to emerge into a displaced position adjacent to the retained deciduous tooth. The newly erupted tooth is often not fully aligned with its opposite tooth and so develops an overgrowth that can even cause chewing restrictions.

In most cases, Dixon says, these retained deciduous teeth can be readily identified and removed. However, it is sometimes advisable to have a veterinarian take a radiograph prior to extraction to ensure the additional tooth is not of the supernumerary variety.

Light breeds and miniature horses are also prone to developing cheek teeth vertical impactions (teeth that are too tightly squeezed by their neighbors and cannot freely erupt into the mouth) when permanent teeth are emerging. However, many larger breeds such as Thoroughbreds also develop this problem. They most commonly cause painless swelling on the bottom of the lower jaw (i.e., eruption cysts, or “3-year-old bumps” and “4-year-old bumps”) that usually disappear after a year or so, because “as the jaw bones lengthen, the impacted cheek teeth have room to erupt normally,” Dixon says.

If there is not enough room for the fourth cheek tooth to erupt normally at one year of age or for the fifth cheek tooth to erupt at two years of age, the (overcrowded) erupting tooth might be displaced and cause a potentially lifelong problem. The displaced tooth might then grow toward the cheeks or tongue, causing painful inflammation, but the most significant problem will be the presence of diastemata (space) between the normal teeth row and the displaced tooth. At these sites, food invariably becomes impacted and the horse can develop painful periodontal disease. If the displacement is very severe, a veterinarian might extract the displaced teeth–a procedure most readily performed in older horses, especially when deep periodontal disease is present.

Abstract Lohse, Collins, and Bradley ignore or misrepresent the arguments we have made concerning “controlled” overshot flaking and the purported Ice-Age Atlantic Crossing. Here, we summarize our previous work and explain again how it directly tests the explicit claims of Stanford and Bradley (2012; Bradley and Stanford 2004, 2006). We also correct the inaccuracies and false accusations of Lohse, Collins, and Bradley, and refute their belief that arguments should be rejected or accepted on the…Expand

Dental disease tends to be more common and be more severe as cats get older, just as in humans. Dental disease in cats is commonly associated with the accumulation of dental plaque (as a result of bacteria in the mouth) and tartar formation, this can result in what is termed ‘periodontal disease’ – disease affecting the teeth and the structures around the teeth that support and keep them healthy.

Plaque is a complex film of bacteria that develops on the surface of teeth. Initially, the plaque layer is not readily visible, but it can be demonstrated by using a ‘disclosing solution’ that stains the plaque film. As the plaque layer grows and becomes thicker, it can often be seen as a soft, grey or white film on the tooth surface.

Tartar is clearly visible and looks like a cream/yellow or brown hard deposit on the tooth surface. In severe cases, a large amount of tartar can develop on the surface of the tooth. Tartar, because it is so hard, cannot usually be removed by simple measures such as brushing the teeth, and dental scaling (performed by your vet under an anaesthetic) is usually required to remove it.

Teeth that are positioned abnormally in the mouth (malaligned) are more likely to accumulate plaque and tartar than those which are correctly positioned. This is because when malaligned, the teeth are not cleaned by the natural abrasion that occurs when food is eaten and chewed. Reasons for misalignment include:

Breed – Very short-nosed breeds or variants in breeds (eg, Persians, Chinchillas, British and Exotic Shorthairs) almost invariably have abnormally positioned teeth, sometimes severely so. Their jawbones are often too small to accommodate the teeth, resulting in overcrowding and misalignment of teeth.

Deciduous tooth retention – In some cats, deciduous teeth (‘baby teeth’ or ‘milk teeth’) can be retained after the permanent teeth have erupted (grown through). If the adult tooth does not push the deciduous tooth out when it erupts, the adult tooth may grow at an abnormal angle, resulting in permanent misalignment.

Trauma or congenital abnormalities – Sometimes the jaw of a cat may have an abnormal shape either because the cat has a congenital abnormality (an abnormality present from birth, such as an undershot or overshot jaw), or perhaps as a result of trauma (eg, a healed, fractured jaw). These can also cause tooth misalignment.

Diet is thought to play a role in the progression of some cats with dental disease. It is possible that feeding only soft/wet food provides little or no abrasive action against the teeth when chewing, and so offers little to prevent plaque formation. Indeed the food itself may accumulate on or around the teeth and encourage bacteria and plaque formation. Dry foods tend to encourage chewing and tend to be more abrasive but the relationship between food and dental disease is complex and the structure of the solid chunks of food is probably more important than whether the food is wet (tinned or sachet) or dry.

Cats should ideally have their teeth examined by a vet at least once every 12 months, and cats that have had dental problems should be examined once every 3-6 months depending on their condition. Generally, the sooner the problem is identified, the easier and quicker it is to treat. Even if the cat’s mouth is being examined every day, dental disease will develop and gradually progress. Cats will quite often not show clinical signs until the disease is advanced by which time many teeth may need to be extracted.

Mild gingivitis – is very common in cats of all ages. It can occur as quickly as 48 hours after cleaning when plaque formation may have begun. Mild gingivitis does not affect the tooth root and home care of the teeth and may easily reverse most cases.

Moderate gingivitis – is also very common. If plaque accumulates on the teeth, the gingiva will become more inflamed as time progresses. Sometimes gum recession can be seen at this stage. Gingival “pockets” may also be evident, which is where the gum has started to separate from the tooth, providing a perfect site for food, bacteria, plaque and tartar to accumulate. If calculus hasn’t already formed, many cases of moderate gingivitis may also be reversed with regular daily home care. However, gingival pocket formation is difficult to reverse.

Severe gingivitis – can be very painful for a cat. The cat may show signs of hypersalivation (drooling), halitosis, pawing at the mouth, difficulty eating and sometimes bleeding from the mouth. Severe gingivitis is common in cats that have a lot of plaque and calculus on their teeth. Gum recession is also common, but may not always be obvious since the gums are so inflamed. Gingival pockets can be seen and are usually deeper than those found with moderate gingivitis. Severe gingivitis cannot usually be reversed with brushing, and often the mouths are too sore to brush. The cat will usually require a general anaesthetic to carry out a scale and polish of the teeth. If there is a severe degree of gum recession exposing the tooth root then the tooth may need to be extracted. Regular brushing is strongly advised afterwards to prevent the disease from recurring.

Cats of around five months of age quite commonly develop gingivitis and you may notice an obvious smell to your cat’s breath. This is usually due to permanent teeth erupting through the gums and loss of deciduous teeth causing gum disturbance and inflammation. You may even find a tooth lying on the floor at home! This is completely normal and will normally take 4-6 weeks to settle down. However, if the cat is showing any signs of discomfort then it should be examined by a vet.

Periodontitis is gum disease that is very advanced and more commonly found in older cats. The gums are usually very inflamed and often recessed. Large amounts of calculus are usually present on the teeth. The ligaments surrounding and supporting the tooth are also diseased and have usually begun to break down exposing the tooth root and causing the tooth to be very unstable. Bacterial infection is common and often pus can be seen surrounding the tooth. Clinical signs are similar to those of severe gingivitis. At this stage, the tooth is so diseased that extraction is the only treatment option.

Various treatments may be used including initial scaling and cleaning of the teeth, follow-up home care, antibiotics and anti-inflammatories. The response to therapy is variable and many cats need corticosteroids to control the inflammation and sometimes other more potent anti-inflammatory or immunosuppressive drugs. In some very severely affected cats, extraction of all of the cheek teeth is helpful – this may be because it removes the site of persistent bacteria in the mouth.

When examining a cat’s mouth a FRL can be difficult to identify (and your vet will often need to probe the teeth under an anaesthetic to identify them), but they appear as a small amount of gum growing out of the tooth. In fact, the gum is inflamed due to the cavity and reacts by ‘filling in’ the hole in the tooth.

FRLs can be diagnosed by dental X-rays or by probing the teeth under general anaesthesia. FRLs are extremely sensitive, and cats will often exhibit signs of pain associated with them. If FRLs are left they cause gradual erosion of the tooth to the point where the crown will fracture off leaving the root behind. The cavities produced by FRLs are not due to decay like human and canine dental cavities, therefore filling them is unsuccessful and affected teeth need to be removed.

Fractured teeth need to be assessed individually before deciding if extraction is necessary. As a general rule, teeth that have fractured through to the dentine or pulp cavity (affecting the nerve and blood supply) are likely to need extraction as the tooth will be painful and it will be at risk of developing an infection and tooth root abscess. If only the tip of a crown is fractured, and the dentine or pulp cavity are not exposed then the tooth may not need to be extracted. However, the enamel covering a cats tooth is so thin that the majority of fractured teeth will almost certainly have to be removed. A probe can be used to assess if the tooth needs extracting. Signs such as pawing at the mouth, hypersalivation and favouring one side of the mouth when eating may be seen in cats with a fractured tooth.

Understandably animals will not sit still and allow dental work to be done, so this should always be carried out under a general anaesthetic. However, dental disease can be easy to overlook, or even ignored. Although anaesthetising a cat can be worrying, the longer the teeth are left, the longer the anaesthetic and procedure will take because dental disease will have progressed. Measures can be taken to reduce the risk of an anaesthetic such as blood tests, and in older cats, intravenous fluid therapy can be given to help support the circulation throughout the anaesthetic. If you are worried about your cat undergoing an anaesthetic then you should discuss your concerns with your vet.

The drawings above show the three basic types of vertical waterwheels: undershot, breast, and overshot. The undershot wheel was used in most of early Bethlehem"s industrial buildings because of the low head of water available from the Monocacy Creek. One or possibly two breast wheels were used in the grist mill-fulling complex, however.

A British engineer named John Smeaton analyzed the relative efficiency of two forms of waterwheels, the undershot and the overshot. The average overshot wheel was far more efficient than the undershot, about 65% as opposed to 25%. The undershot wheel is an impulse wheel, since the water imparts its energy by pushing. If the hillside is steep, the water moves fast at the bottom and can push impressively against the paddles of an undershot wheel. The overshot wheel is a gravity wheel. It is a series of buckets attached to the outside of a big circle. The water goes into a container at the top and drops all the way down.

The growth of mills was accompanied by the growth in the power of waterwheels. From the first half of the 18th century to the first half of the 19th century, the average horsepower increased 300% to 12-18 horsepower. the largest wheels were 60 and 70 feet in diameter and capable of producing upwards of 250 horsepower. Taking advantage of America"s abundance of wood, most waterwheels were constructed of wood. Usually, only the bearings and teeth were made of metal. However, wooden wheels needed replacement roughly every 10 years.

Many people may have a prognathic face from birth, and it may not be a problem. Prognathism can cause complications that may require treatment, such as misaligned teeth.

There was a final straw, of course. The Boeing 727-sized jet we took from Xian (another Soviet model) made a landing at the Beijing Airport that still has my adrenaline pumping. The pilot came in sideways, overshot the touchdown point, slammed on his brakes and then skidded down the runway past the place he was supposed to turn off to go to the terminal building. Worst landing I`ve had anywhere, any time. It`s what they call a ""hard"" landing. Nice phrase;

RUDIMENTARY DENTAL EXTRACTIONS were performed in China as early as 6,000 BC, and there is also evidence that they used wires to stabilize teeth. They didn’t seem to be very interested in straightening teeth, but they were quite advanced when it came to treating endodontic problems.

The typical oral hygiene routine for a person in ancient China was to gargle salt water or tea. It became common in the Tang dynasty to soak a willow twig in water before bed and chew on it in the morning. The willow fibers would protrude like a comb and scrub the teeth clean. That’s where the Chinese idiom “chew wood at dawn” comes from.

Some people from that period had access to toothbrushes made of animal bone and hair. They also had an early form of toothpaste made from boiling honey locust fruit, ginger, foxglove, lotus leaves, and other herbs to reduce gum inflammation, ease toothaches, and whiten the teeth.