Rock Valley Dental

1302 10th Street

Rock Valley, IA 51247

(712) 476-2749

Meet The Team


Our dental assisting team can answer any questions you might have ranging from simple appointments to technical dental treatment procedures. They will help you prepare for your visit, answer your questions about post-operative care and have even been known to hold a hand during dental treatment.

  • Sarah Johnson
    Front Office

    Sarah has enjoyed working in the dental field since high school and has been trained by many great dental professionals during her career. As a Registered Dental Assistant and Treatment Coordinator, she has had the opportunity to learn about different dental needs from many cultures worldwide, and she is amazing at solving about any problem there is! Rock Valley is her longtime home along with her local family. Sarah is excited to be serving her community.

  • Mary Kosters

    Mary has been working in the dental field for the past 34 years. She enjoys all different aspects of her job, but especially interacting with our great patients every day. Mary and her husband, Dave, spend most of their spare time with family and friends. They have 3 married children and 9 grandchildren. They love warm weather activities; camping, motorcycle riding, bicycle riding, and just being outdoors. Mary tries to live a healthy and active lifestyle and is thankful everyday for all the blessings in her life.

  • Holli Dryfhout

    Holli has been working in the dental field for 37 years in Rock Valley.  She and her husband, Bill, live in Doon.  Holli considers herself blessed by getting to know many patients through the years.  Her goal each day is to treat each patient as family.  She enjoys biking, scrap-booking, and spending time with family.

  • Krista Spaans

    Krysta Spans joined our office Feb. of 2021. She graduated from West Lyon High School in 2020 worked hard early in her career to become a Certified Dental Assistant. Krysta enjoys working and caring for our patients here at Rock Valley Dental, and she is known for her sweet, happy personality. Krysta and her husband Tristan got married in 2023 and we are excited to see their future grow! When Krysta isn’t in the office she likes to go running and spend time with her family and friends.

  • Jessica Bakker

    Jessica is one of the smiling faces you can’t help but notice in our office. She joined our team as a dental assistant in 2023, and she is a daily beacon of positivity and joy every day for our patients and staff. Jessica lives on a farm close to Hull, Iowa with her husband, Darren, and four children, Rielly, Ashlynn, Breckken, and Kenzlee. Jessica is also an EMT for the Hull Ambulance Crew, which speaks well to the type of person she is. In Jessica’s free time, she enjoys being outdoors, gardening, and spending time with all the farm animals. Jessica always enjoys spending time with her family and friends.

  • Nicole Van Beek

    Bio Coming Soon`

  • Emma Knobloch

    Bio Coming Soon

  • Jocelyn Aranda

    Bio Coming Soon


Our dental hygienists emphasize good home care of the teeth and gums and provide comfortable and thorough preventive and therapeutic dental treatment in a caring setting. We are proud of our hygiene team's committment to quality and the outstanding care they provide to all the patients in our practice.

  • Amy Ripperda

    Amy completed her Dental Hygiene Degree at the University of South Dakota. She started working with Dr. Jespersen shortly after graduating in 1990 and later in the same practice with Dr. Koth since July 2012. Amy lives on an acreage outside of Larchwood with her husband, Jay. They have one daughter, Tiffany, who is finishing her degree in accounting and business.  Amy and Jay enjoy spending time camping and fishing, mostly in Chamberlain, South Dakota. Amy thanks all of her patients for letting her assist them with their hygiene care for the past 28 years.

  • Kali Van Veldhuizen

    Kali was born and raised in Rock Valley. Kali graduated from the Rock Valley Community School in 2006 and obtained her Bachelors of Science degree in Dental Hygiene from the University of South Dakota in 2009. Kali started working for Dr. Jespersen in high school helping out wherever she was needed, and returned to the team as a dental hygienist after college. Kali enjoys practicing in her hometown and seeing familiar faces everyday. When Kali is not at the office she stays very busy with her growing family. She currently has four children, Trent, Kason, Brett, and Kenna. Kali enjoys being outdoors, playing volleyball, exercising, and spending time with family and friends.

  • Bayleigh Dickerson

    Bayleigh became a part of our team in 2020 following her graduation with a Dental Hygiene degree from the University of South Dakota. She currently resides in Ashton, IA where she enjoys reading books, riding her bicycle, and spending time with her family. Bayleigh and her fiancé Evin anticipate making Rock Valley closer to home, following their wedding in 2023. Bayleigh brings great energy to our team and is loved by patients at Rock Valley Dental. We can ensure that she can put a smile on any face!

  • Brittany Keller

    Bio Coming Soon

  • Trela Knueven

    Trela grew up in northwest Iowa on a farm. She then went to dental hygiene school at USD and graduated there in 2004. Trela is so kind and easy to talk to, a byproduct of working in Sioux County in the dental field for over 19 years!

    Trela currently lives on an acreage right outside Lester with my husband Jason and her children. They have been married 19 years and have three children, Kiersten, Treyven, and Jaxon.

    Trela loves to go camping, biking, hiking, swimming, and be active doing lots of exciting things like scrapbooking all the memories her family makes together! She also loves gardening, walking, and Trela Truely has a heart for helping others. She is known for saying, 'I always say I truly love people of all ages!'

    Trela enjoys working at Rock Valley and meeting all the nice people that have come in the door!


Our Front Office Team greet you with a smile when you walk in the door! They can help you make appointments, answer questions about your dental treatment plan and assist you with financial arrangements.

  • Whitney Silva

    Whitney is a native to Rock Valley after graduating from Rock Valley Community School in 2008. After high school she attended Southeast Technical Institute in Sioux Falls, SD where she received her diploma in Surgical Technology. She was a surgical technologist for 12 years before returning back to Rock Valley after living in North Carolina with her family for some time. Whitney loves spending time with her husband Antonio, and two children, Antonio Jr. and Kiana, along with additional family and friends. She also enjoys reading, coloring, and gaming on an Xbox or PC. Rock Valley Dental is so happy to have Whitney with her healthcare background and savvy computer mind to help handle all the needs of our patients.

  • Glenda Riebeling

    Glenda joined Rock Valley Dental front desk team in 2022, and is the pleasant and kind voice behind the phone that will help schedule all your dental appointments. She has a Business Administration Degree from Southeast Technical Institute. Glenda has always loved working with and helping people and she has enjoyed her time learning about dentistry! Glenda lives in Rock Valley with her two daughters, Kylee and Brooklyn. In her spare time she enjoys camping with family and friends.

Contact Us

We look forward to hearing from you.

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Hours of Operation

Find Out When We Are Open

Rock Valley Dental


8:00 AM-4:00 PM


8:00 AM-4:00 PM


8:00 AM-4:00 PM


8:00 AM-4:00 PM